OLD POST OFFICE BUILDING HSR

Transcription

1 OLD POST OFFICE BUILDING HSR 1016

2 OLD POST OFFICE BUILDING HSR GLOSSARY OF ARCHITECTURAL TERMINOLOGY Acanthus: A plant whose large, stylized, scalloped leaves on a curving stem are commonly found on Corinthian and composite capitals and whose leaves and flowers are often used on other carved ornament. Acroteria: Ornaments used at the corners, peaks, or ridge line of a roof. Singular = acroterion. Acorn: An ornament in the shape of an acorn, often used as a pendant of finial ornament. Aggregate: Small particles of rock incorporated in a concrete (q.v.) mixture to increase strength. Anodize: The intentional formation, by electrolytic action, of a thin, hard, noncorrosive, oxide film on the surface of a metal, particularly aluminum, to provide protection from further oxidation. Antefix: A decorated upright slab used in classical architecture to close or conceal the end of a row of coping stones or other horizontal wash surface. Often decorated with anthemion. Anthemion: A favorite classical floral motif based on a stylized honeysuckle (or palmette). Apophyge: That part of a column or pilaster which is molded into a concave sweep where the shaft springs form the base or terminate in the capital. 1017

3 OLD POST OFFICE BUILDING HSR Applied Ornament: Ornament which is nailed, laid on, or otherwise fastened to the work rather than an integral aspect of it. Apron: A panel below a window sill, often decorated. Arcade: A series of arches supported by columns, piers, or pilasters. Arch: A self-supporting structure that span an opening usually rounded and composed of voussoirs. Architrave: The lowest member of an entablature, being the beam that spans from column to column, resting on the capitals; the ornamental molding around the openings of a door or window. Areaway: A recessed exterior passageway located adjacent to a foundation wall and intended to provide light and air in basement areas. Ashlar: Hewn masonry blocks cut to show even faces and square edges and laid in horizontal courses with vertical joints. Attic: In classical architecture, the story(ies) built above the wall cornice. Awning: An adjustable cover, typically of canvas, placed over door and window openings to protect against the elements. Balcony: A projecting platform enclosed by a balustrade, typically placed in front of an upper window or door and supported by brackets of pillars, or cantilevered. Baluster: One of a series of short posts, typically circular in section and often quite ornamental, used to support a hand rail or coping, and forming a balustrade. Balustrade: A series of balusters and the handrail or coping they support, or a structure similarly composed, the composition acting as a railing, fence, parapet, or enclosure, often decorative. Base: The lowest of the three main parts of a column, being the part on which the shaft rests; the lowest part of a building or other architectural member, often distinguished in its treatment from the upper parts of the building or member. 1018

4 OLD POST OFFICE BUILDING HSR Baseboard: The lowest member of an interior wall consisting of plain or molded protective board that covers the gap between a wall or partition and adjacent finish flooring. Basement: Usually the lowest story of a buildin& either partly or entirely below grade; the lower part of the wall or walls of any building. Base molding: The molding at the upper edge of a baseboard. Base shoe: The molding at the lower edge of a baseboard. Baseboard: A horizontal board, plain or molded, which extends around an interior wall, covering the juncture of the floor and the wall, typically topped by a base molding and jointed to the floor by a base shoe. Basket weave: A masonry bond or ornamental treatment resembling the woven pattern of a basket. Battered: Inclined from the vertical. A wall is said to batter when it recedes as it rises. Bay: One of a series of principal uniform architectural divisions, usually vertically orientated. Beaux Arts: A rich, classically inspired style of architecture as developed at the h ede s Beaux-Arts. In the late nineteenth and early twentieth centuries, this Parisian academy had a profound impact in training the foremost American architects. Bead-and-Reel: A semi-round convex moulding decorated with a pattern of disks alternating with round or elongated beads. Bearing wall: A structural wall that supports a vertical load such as a floor roof, or ceiling, in addition to its own weight. Bedding Mortar: A cementitious material used to align and separate masonry units which may not be visible after installation. Blind: Blank, having no opening. Blind arcade: An arcade applied to the surface of a wall. 1019

5 OLD POST OFFICE BUILDING HSR Bond: The pattern in which bricks or stones are arranged in the formation of a wall. Bond, Common: A brick masonry bond composed of five or six stretcher courses to one header course; also called American bond. Bond, Stretcher: A brick masonry bond in which all units are laid lengthwise with the vertical joints of alternate courses staggered. Bracket: A general term for a member, often treated with scrolls or ornament, projecting from a wall and intended to support a weight, as a cornice, etc. Caduceus: The symbolic staff of a herald; a representation of a staff with two entwined snakes and two wings at the top; the traditional symbol of a physician. Capital: The topmost member of a column, pilaster, etc., which takes a variety of forms and typically carries an architrave, arcade, etc. Case/Casing: A finished frame, flat or molded, consisting of jamb and lintel, and placed in an opening to receive a door or window. Casement Window: A window which swings open along its entire length, usually on hinges fixed to the sides of the opening into which it is fitted. Cast-Iron: An iron alloy, usually including carbon and silicon, with high compressive but low tensile strength. It may be cast in a variety of shapes; usually mechanically fastened. Cavetto: A hollow member or round concave moulding containing at least the quadrant of a circle, used in cornices. Cement: A naturally occurring or man-made bonding material used in the formulation of concrete Chair Rail: A horizontal interior molding placed at the height of a chair back to protect the wall. Chamfer: A molding or the corner of an element that is cut off at an angle. 1020

6 OLD POST OFFICE BUILDING HSR Classical Architecture, Classicism: Referring to the architecture of Hellenic Greece and Imperial Rome on which the Italian Renaissance and subsequent styles such as the Baroque and the Classical Revival based their development; in short, the inspiration for much of western architecture in the past 2500 years. Classicism refers to the revival or return to the principals of the ancient Greek and Roman styles. Colonnade: A row of columns supporting an entablature Column, Corinthian: One of the five classical orders of architecture, characterized by a capital with volutes rising from acanthus leaves. Column, Doric: One of the five classical orders of architecture, characterized by a simple capital. Column, Ionic: One of the five classical orders of architecture, characterized by a capital composed of two volutes. Compo: A common term for composition, a type of paste made from wood, fiber, and glue and used to fabricate ornamental mouldings. Concrete: A mixture of cement, coarse and fine aggregate, sand, and water compounded in specific proportions that, when set, forms a hard material capable of resisting structural loads. Concrete is frequently reinforced with internal steel members to provide extra strength. Condensate: Water produced as the result of changes in temperature or humidity. Conductor Head: An enlarged water receiver located near the top of a downspout and sometimes treated decoratively. Coping: A protective cap, top, or cover of a wall, parapet, pilaster, or chimney that is typically sloped, double beveled, or curved to shed water Cornice: The uppermost division of an entablature; a horizontal ornamental molding at the top of a building or other prominent architectural element, such as a window or door. Course: A continuous layer of bricks, or of stones of equal thickness in a wall. 1021

7 OLD POST OFFICE BUILDING HSR Decorative or raised courses are used to emphasize horizontality. Curing: The process of allowing a compound to complete chemical and physical integration necessary for development of its useful properties. Cyma Mould: A moulding composed of a double curve. In the cyma recta, the upper part is concave and the lower, convex. In the cyma reversa, the upper part is convex and the lower, concave. Delamination: A failure in a laminated assembly characterized by the separation or loss of adhesion between plies. Demising Partition: A non-load bearing interior wall intended to subdivide a large area Denticulated: Ornamented with dentils. Dentil: One of a series of small, square tooth-like blocks forming a molding that is used typically in cornices. Dogleg Stair: A half-turn stair with no open well. Dentil: One of a band of small, square, tooth-like blocks forming part of the characteristic ornamentation of the Ionic, Corinthian, Composite and, occasionally, Doric orders. Dolomitic: Marble walls and wainscots in the main entrance lobby and in the main stair and elevator lobbies (all floors) are primarily a vein-cut ferruginous dolomite (or related variant) with a polished surface (most likely Minnesota Stone from the Kasota district). Dolomites are classified commercially as a type of marble, however they are composed primarily of magnesium carbonate instead of calcium carbonate as with most limestones and marbles. Dolomitic marbles are not technically a true marble being only partially altered from the limestone state. Doric Order: The column and entablature developed by the Dorian Greeks, sturdy in proportion, with a simple cushion capital, a frieze of triglyphs and metopes, and mutules in the cornice. 1022

8 OLD POST OFFICE BUILDING HSR Dormer: A window building into a sloping roof with a roof of its own. Door, Bi-fold: A door consisting of two pairs of separately hinged folding leaves. Door, Casing: The finished, often decorative framework around a door or window opening, especially the portion parallel to the surrounding surface and at right angles to the jambs. Door, Double-leaf: A pair of doors hung in the same doorframe. Door, Double Pocket: Two doors that slide in opposite directions into openings in a wall. Door, Side-light: A window at the side of a door or another window. Door, Single-leaf: A door hung on hinges that permit it to swing in one direction only. Door, Transom: A window above a doorway. Double-loaded Corridor: A corridor placed centrally within a building or wing, desirable for providing the flanking rooms with access to light and air. Dowel: A pin, frequently concealed, used in the assembly of a multi-part component. Downspout: A vertical pipe used to conduct water from a roof drain or gutter Drop: The bottom part of a newel that does not meet a floor but hangs down into the open space below, often ornamented. Dutchman: A flush patch inserted into a damaged item and made of the same material as that item. École des Beaux Arts: See Beaux Arts. Egg-and-Dart: A repetitive motif consisting of egg-shaped units alternating with dart-like units, frequently used to enrich mouldings. Electrolyte: A substance in which the presence of electricity is induced by chemical 1023

9 OLD POST OFFICE BUILDING HSR reaction Elevation: A wall of a building. Engaged: Attached, or apparently attached, to a wall by being partly embedded or bonded to it, as an engaged column. Entablature: The horizontal member composed of an architrave, a frieze, and a cornice, and typically carried by columns or pilasters, but also used with other architectural features, such as doors and windows. Exposed Aggregate Concrete: Concrete, the surface of which has been blasted with a water wash during curing in order to expose the aggregate closest to the surface. Façade: The front of a building facing a public way or space, particularly distinguished by its architectural treatment. Fascia: In classical architecture, the flat member of the architrave; also, any flat vertical member. Fanlight: A window, usually semicircular in shape, located above a door. Fenestration: The design, proportioning, and disposition of windows and other exterior openings of a building. Fleur-de-lis: An ornament composed of three pointed members, the center one upright and the sides curved outward, all separated by a horizontal bar from three similar members, or a single vertical one, below. Flue: An incombustible and heat-resistant enclosed passage, usually within a chimney, intended to control and carry away products of combustion from a fireplace or furnace or other noxious fumes. Flute: One of a series of vertical parallel grooves, typically used in the shafts of columns, but also used in moldings. Foliate Ornament: Any leaf pattern, whether carved, painted, or applied, used to enrich mouldings, panels, or other surfaces. 1024

10 OLD POST OFFICE BUILDING HSR Freeze/thaw cycle: The process by which materials are damaged by the expansion and contraction of water trapped within those materials. Fret: Geometric ornament composed of lines joined at right angles and repeated over a surface. Friable: Easily crumbled or pulverized; easily reduced to powder. Frieze: A member of an entablature located between the architrave and cornice, may be plain or ornamented with sculpted figures of foliage, or triglyphs and metopes, depending on the order used. Furring: Concealed strips of wood or metal attached to a substrate to provide a level surface for a finish material. Gable: A roof having two slopes that meet at a ridge and form a triangle. Galvanized Metal: Metal which is coated by immersion in molten zinc to prevent rusting. Girder: A large or principal beam used to support concentrated loads at isolated points along its length. Glazing Compound: A plastic compound use for holding glazing panes in window sash. Greek-fret: A continuous ornament on a flat surface consisting of a series of narrow straight bands turned at a succession of right angles. Grout: Concrete mortar of a heavy liquid consistency that contains small aggregates and is capable of being poured or injected under pressure to fill small interstices. Guilloche: An ornament composed of two or more curved bands that continuously intertwine, creating round openings that are often filled with ornament. Guttae: One of a series of pendant ornaments, generally in the form of the frustrum of a cone, usually found on the underside of the mutules of Doric entablatures. Hipped Roof: A roof which slopes upward from all sides of a building. 1025

11 OLD POST OFFICE BUILDING HSR Herringbone: A zigzag pattern, often used ornamentally. Hip Roof: A roof in which all four sides slope upward, forming four hips. Hood: A cover, often decorated, placed over an opening, especially over a door or window. HVAC: Heating, ventilating and air-conditioning. Interior Design: The art, business, or profession of planning the design and supervising the execution of architectural interiors, including their color schemes, furnishings, fittings, finishes, and sometimes architectural features. Isodomum: In classical architecture, an extremely regular masonry pattern in which stones of uniform length and height are set so that each vertical joint is centered over the block beneath. Horizontal joints are continuous and vertical joints form discontinuous straight lines. Jamb: The vertical member located to either side of a door or window. Keystone: The central voussoir of an arch; the middle of an archivolt, often elaborately embellished. Landing: The resting place between two flights of stairs, or the part of a floor at the head of a flight of stairs. Lath: Wood strips, metal strips or channels, attached to framing members used as a supporting base for plaster, tile, shingles, or other building materials. Light: A pane of glass. Lintel: A horizontal member located above an opening, as a door or window opening, to carry the weight of the wall above. Louver: A system of overlapping horizontal slats placed in an opening to regulate ventilation. Marble: A metamorphic rock (undergone a change in structure, texture, or 1026

12 OLD POST OFFICE BUILDING HSR composition) of crystallized limestone, consisting mainly of calcite or dolomite, capable of taking a high polish and used especially in architecture and sculpture. Masonry Coursing: A horizontal row of masonry units Massing: A unified composition of two-dimensional shapes or three-dimensional volumes, especially one that has or gives the impression of weight, density, and bulk. Metope: The plain or decorated space between the triglyphs in a Doric frieze. Molding: A decorative member of long proportions shaped into one of a variety of contours to introduce variations of light, shade, and shadow into a design. Molding, Bead: A semicircular, convex molding; also called a half-round; a molding composed of a series of round elongated elements. Molding, Bead and Reel: A rounded convex molding composed of disks alternating with beads, either single of multiple, round, or elongated. Molding, Cavetto: A concave molding with the profile of a quarter of a circle. Molding, Crown: Any molding forming the topmost finishing member of a structure or architectural feature. Molding, Cyma Recta: An ogee molding composed of a concave arc above a convex arc. Molding, Cyma Reversa: A reverse ogee molding composed of a convex arc above a concave arc. Molding, Egg and Dart: A molding consisting of egg-shaped elements alternating with arrow- or date-like element. Molding, Leaf and Dart: A molding composed of a series of alternating leaf-like figures and darts; also called leaf and tongue. Molding, Medallion: An ornamental tablet, panel or plaque, typically oval in shape and providing the background for a carved figure. Molding, Ovolo: A convex molding with a profile larger than a one-quarter of a 1027

13 OLD POST OFFICE BUILDING HSR circle and smaller than one-half of a circle. Molding, Pearl: A molding composed of a series of nearly spherical elements. Molding, Scotia: A deep, concave molding, typically used at the base of a column. Molding, Quarter Round: A convex molding, usually a quarter of a circle in profile, which may be ornamented with other moldings, such as the egg and dart. Molding, Sunk: Any molding recessed behind the surrounding surface, as in a sunk fillet. Molding, Sunk Fillet: A hollow molding with a narrow, square cross-section. Molding, Three-Quarter Round: A convex molding, usually three-quarters of a circle in profile. Molding, Torus: A convex molding with semicircular profile. Mortar: A mixture of plaster, cement, or lime with a fine aggregate and water that is used for pointing and bonding bricks and stones. Mullion: A vertical member divided a window into lights, each of which may be further sub-divided into panes. Munsell System: A system of precise identification of the elements of color based on spectrographic analysis and permitting assignment of a numerical designation for accurate color matching. Muntin: A secondary framing member that holds panes within a window, window wall, or glazed door. Mutules: A sloping flat block on the soffit of the Doric cornice, usually decorated with rows of six guttae each; occurs over each triglyph and between each metope of the frieze. Nèo-Grec: A highly-stylized interpretation of Greek architecture developed in France during the late nineteenth century. 1028

14 OLD POST OFFICE BUILDING HSR Newel-Post: An ornamental post located at the head or foot of a stair that supports a handrail. Newel: The post at the top, bottom, and turning points of a stair, typically larger and more elaborate than the balusters. Order: In classical architecture, one of several varieties of columns, with or without a plinth, crowned by an entablature consisting of an architrave, frieze, and cornice. Oxidation: A physical process, frequently destructive, associated with the effects of the chemical action of oxygen on a material. Oxide Jacking: The increase in a ferrous material s cross section caused by rusting. The resultant forces of this process are sufficient to dislodge adjacent structural members. Paint Seriation: An investigation and listing of existing paint layers in the order in which they were applied to a surface. Panel: A flat surface distinguished from the surrounding area by a molding or other ornament. Parapet: A low protective or decorative wall on a bridge, gallery, balcony, or, most commonly, above the cornice of a building. Parquet: Inlaid wood flooring of closely fitted pieces, usually geometrical, and often employing two or more colors. Patera: A small disk decorated with leaves or petals. Patina: Any thin oxide film which forms on a metal, often multicolored. Pavilion: A prominent portion of a facade, usually central or terminal, identified by projection, height, and special roof form. Pedestal: A support for a column, statue, or urn. Pediment: In classical architecture, the triangular gable end of the roof above a horizontal cornice. Also, an ornamental surface used above over doors or windows; 1029

15 OLD POST OFFICE BUILDING HSR usually triangular but may be curved. Pilaster: A member appearing to be an engaged pier with its base, shaft, and capital, but providing no support. Plate Glass: Flat, transparent, relatively thin, high-grade glass with polished surfaces and without blemish or distortion Plinth: A square or rectangular base for column, pilaster, or door frame. Pocket Door: A door capable of being concealed within a hollow wall. Portico: A colonnade supporting a roof at the entrance to a building, distinguished by number and placement of columns. Portland Cement: A combination of clay and calcareous minerals which are calcined and pulverized to form a highly hydraulic material. Preservation: Application of measures designed to sustain the form and extent of a structure essentially as existing. Preservation aims at halting further deterioration and providing structural safety but does not contemplate significant rebuilding. Preservation includes techniques of arresting or slowing down the deterioration of a structure, and improvement of structural conditions to make a structure safe, habitable, or other wise useful. Primer: A coat of paint intended to act as a base for future finish coats. Pseudisodomum: In ancient masonry, composed of layers or courses alternately thick and thin. (Vitruvius II) Purlin: A horizontal structural member laid on the principal rafters of a roof to support common rafters. Quoin: One of a series of alternately large and small masonry units that typically form the corner of a building and are often distinguished from the adjacent masonry by varying surface treatment. Raceway: A concealed passageway intended to hold electrical wiring. 1030

16 OLD POST OFFICE BUILDING HSR Rail: A horizontal structural member of a door or window. Rails and Stiles: Members which frame and separate the components of a panelled door, etc. Rails are the horizontal members and stiles, vertical. Raised Panel: A framed decorative panel that contains a center portion that is thicker than the surrounding material that supports it. Rehabilitation: The process of returning a property to a state of utility, through repair or alteration, which makes possible an efficient contemporary use while preserving those portions and features of the property which are significant to its historical, architectural, and cultural values. Repair: Replacement of deteriorated materials which it is impractical to save such as broken window glass, severely rotted wood, etc. Repair activities also include the rehabilitation, strengthening or reclamation of items worn to the point that they can no longer perform their intended function. In historic buildings, stock used for repairs should be as close as possible to the original in composition of materials, in methods of fabrication and in manner of erection. Repointing: The filling and tooling of open joints with new mortar. Restoration: The process of accurately recovering, by removal of later work and the replacement of missing original work, the form and details of a structure or part of a structure, together with its setting, as it appeared at a particular time. Riser: A vertical member that closes the open area located between stair treads. Roof Ventilator: A roof-mounted device intended to permit the removal of air and moisture from a space below. Rosette: A carved, rounded ornament resembling a flower. Sash: That portion of a window that contains its glazed panels; may be moveable or fixed. Screen Wall: A wall whose essential function is to separate, protect, seclude, or conceal, but not necessarily to support. 1031

17 OLD POST OFFICE BUILDING HSR Scallop: Ornament representing a ribbed shell. Scroll: Ornament in the form of a wound spiral, often applied singly to brackets or joined continuously in a molding, when it is typically called a Vitruvian scroll. Shaft: The long, central part of a column (terminated by a base and capital). Shafts are of stone, wood, or other material. Stone shafts of a single stone are monolithic; others are divided into drums or short, roughly cylindrical, segments. Soffit: The exposed undersurface of any overhead component of a building such as an arch, balcony, beam, cornice, lintel, or vault. Spandrel: A panel located between vertical structural members. Spall: A small fragment or chip removed from the face of a stone or masonry unit by a blow or some other type of physical or chemically induced stress, resulting in the formation of a shallow, quasi-circular crater. Stair, Tread: The horizontal upper surface of a step in a stair. Stair, Riser: The vertical facing of a stair step. Standpipe: A vertical pipe in which water can be pumped, usually in the case of fire. Stile: An upright structural member of a door or window frame. String course or (belt-course): A continuous horizontal band, typically molded and projecting from the face of a building. Stringer: The structural supporting members of a staircase. Story: A complete horizontal division of a building, having a continuous or nearly continuous floor and comprising the space between two adjacent levels. Stud: In frame structures, a slender vertical structural member used in wall and partition construction. Substrate: A concealed material that supports a finish surface. Sugaring: The gradual surface disintegration of some building stones, possibly caused 1032

18 OLD POST OFFICE BUILDING HSR by salts dissolved in and transported through the stone by moisture and consequent dissolution of the binder. Carbonate stones, especially fine grained marble, are particularly susceptible to this granular condition. Terrazzo: A mosaic flooring consisting of small pieces of granite or marble set in mortar and given a high polish. Terra-Cotta: Hard, glazed or unglazed, fired clay commonly used for ornamental work roof and floor tile. Tessera: A small, squarish piece of colored marble, glass, or tile, used to make mosaic patterns, either geometric or figurative. Tongue and Groove: A joint formed by inserting a continuously projecting part of one member into the groove of another member. Tooling, Mortar: The method by which pointing mortar is applied to the joints between masonry units. Torchére: An ornamental support for a light source. Traffic Sealant: A sealant whose properties make it well suited for installation in areas subject to high abrasion, such as construction joints in sidewalks and steps. Transom: A glazed light, usually rectangular, above a door. Transom Bar: A horizontal member separating a door or window from the transom above it. Tread: The horizontal member of a stair step. Triglyph: The blocks alternating with metopes in the Doric frieze, composed of two vertical grooves at the center and two half-grooves at the edges. Trompe l oeil: A decorative technique using accurate representation of details, scenes, etc., to create an illusion of reality. Truss: A structure composed of a combination of members, usually in a triangular 1033

19 OLD POST OFFICE BUILDING HSR arrangement, that constitutes a rigid frame. Veneer: A decorative layer of brick, wood, or other material used to cover a lesser structural material, thereby giving an improved appearance. Vent Stack: A pipe connected from a plumbing system to an outdoor space that allows an equalization of air pressure within a plumbing system. Urn: A vase with a rounded body on a base, traditionally used to contain the ashes of the dead. Vestibule: A small entrance hall between the outer door and inner space. Voussoir: A masonry unit, typically wedge-shaped, used to construct an arch. Wainscot: A decorative or protective facing applied to the lower portion of an interior partition or wall, such as wood paneling. Watertable: A plain or molded ledge or projection, usually at the ground floor level, that protects a foundation from rain runoff. GLOSSARY OF PAINT TERMS Abrasive: (Method of removing paint) Abrading the painted surface by manual and/or mechanical means such as scraping and sanding. Generally used for surface preparation and limited paint removal. Acrylic waterborne paints (latex): Suspension of acrylic or polyvinyl resins in water, with other resins, plus hiding and coloring pigments and extenders. Dries by evaporation. Commercially produced acrylic or latex enamels are also available in a complete range of gloss levels which are produced with the addition of various acrylic polymers. Use on interior plaster especially. Belt Sander: (Abrasive Method Mechanical) The belt sander can be used for removing limited layers of paint. The abrasive surface is a continuous belt of 1034

20 OLD POST OFFICE BUILDING HSR sandpaper that travels at high speeds and consequently offers much less control than the orbital sander. Because of the potential for more damage to the paint or the wood, use of the belt sander (also with a medium grit sandpaper) should be limited to flat surfaces and only skilled operators should be permitted to operate it within a historic preservation project. Binder: The most common binder in interior paints was, and still is, oil. Chalk was sometimes added to water based paints to help bind the pigment particles together. Other common binders included hide glue and gelatin. Brushes: Natural bristle brushes now have competition from synthetic brushes made of nylon or polyester which work well for applying either oil/alkyd or latex paints. Being harder than natural bristles, they tend to last longer. Brushes come in a wide and very specific variety of types suited to different types of work. One strong advantage of brushing paint on is that the paint is forced onto the surface and into all of its imperfections. Thus a good brushed on paint job may last longer if the substrate is sound and the primer and finish coats are compatible and of top quality. Calcimine/whitewash: Modern water based paints such as calcimine can be purchased today and have much the same appearance as the early ones. The same is true of modern whitewash, although today s whitewashes do not leave the same ropy surface texture as the early ones. Caustic strippers (Chemical Method): Until the advent of solvent-base strippers, caustic strippers were used exclusively when a chemical method was deemed appropriate for total paint removal prior to repainting or refinishing. Chalking: Powdering of the paint surface is caused by the gradual disintegration of the resin in the paint film. (The amount of chalking is determined both by the formulation of the paint and the amount of ultraviolet light to which the paint is exposed.) In moderation, chalking is the ideal way for a paint to age, because the chalk, when rinsed by rainwater, carries discoloration and dirt away with it and thus provides an ideal surface for repainting. In excess, however, it is not desirable because the chalk can wash down onto a surface of a different color beneath the painted area 1035

21 OLD POST OFFICE BUILDING HSR and cause streaking as well as rapid disintegration of the paint film itself. Also, if a paint contains too much pigment for the amount of binder (as the old white lead carbonate/oil paints often did), excessive chalking can result. Chemical: (Method of removing paint) Softening of the paint layers with chemical strippers followed by scraping and sanding. Generally used for total paint removal. Cracking and Alligatoring: Advanced staging of crazing. Once the bond between layers has been broken due to inter coat paint failure, exterior moisture is able to penetrate the surface cracks, causing the wood to swell and deeper cracking to take place. This process continues until cracking, which forms parallel to grain, extends to bare wood. Ultimately, the cracking becomes an overall pattern of horizontal and vertical breaks in the paint layers that looks like reptile skin; hence, alligatoring. In advanced stages of cracking and alligatoring, the surfaces will also flake badly. Crazing: Fine, jagged interconnected breaks in the top layer of paint results when paint that is several layers thick becomes excessively hard and brittle with age and is consequently no longer able to expand and contract with the wood in response to changes in temperature and humidity. As the wood swells, the bond between paint layers is broken and hairline cracks appear. Although somewhat more difficult to detect as opposed to other more obvious paint problems, it is well worth the time to scrutinize all surfaces for crazing. If not corrected, exterior moisture will enter the crazed surface, resulting in further swelling of the wood and, eventually, deep cracking and alligatoring, a Class III condition which requires total paint removal. Crazing can be treated by hand or mechanically sanding the surface, then repainting. Although the hairline cracks may tend to show through the new paint, the surface will be protected against exterior moisture penetration. Decorative Painting: In interiors, paint could be used creatively and imaginatively, most often to decorate rather than to protect. Decorative forms included stencilling, graining and marbleizing, and trompe l oeil. Electric Heat Plate: (Thermal Method) The electric heat plate operates between 500 and 800 degrees Fahrenheit (not hot enough to vaporize lead paint), using about

22 OLD POST OFFICE BUILDING HSR amps of power. The plate is held close to the painted exterior surface until the layers of paint begin to soften and blister, then moved to an adjacent location on the wood while the softened paint is scraped off with a putty knife (it should be noted that the heat plate is most successful when the paint is very thick!). Electric Heat Gun: (Thermal Method) The electric heat gun (electric hot-air gun) looks like a hand-held hair dryer with a heavy-duty metal case. It has an electrical resistance coil that typically heats between 500 and 750 degrees Fahrenheit and, again, uses about 15 amps of power which requires a heavy-duty extension cord. There are some heat guns that operate at higher temperatures but they should not be purchased for removing old paint because of the danger of lead paint vapors. The temperature is controlled by a vent on the side of the heat gun. When the vent is closed, the heat increases. A fan forces a stream of hot air against the painted woodwork, causing a blister to form. At that point, the softened paint can be peeled back with a putty knife. Enamels: Modern alkyd paints are adjusted with the addition of synthetic varnishes to produce a complete range of gloss levels. Fillers, or extenders: such as clay and chalk were put in to make oil paints flow better and to make them cheaper as well. Glazes: Often part of historic paint treatments. Traditionally oil and turpentine, sometimes with a scant amount of pigment, today s glazes can be formulated with a water base and are relatively simple to apply by brush. The glaze is capable of providing protection as well as a more accurate historic appearance that includes a greater depth to the finish. Graining/Marbleizing: Painting a plain or common material, such as wood or plaster, to look like a finer material like a finer wood or marble. Heavy Metal Compounds: In addition to lead, early oil paints also had cobalt or other heavy metal compounds in them to accelerate drying. A small amount of mercury is also included in some latex paints to help prevent mildew and mold formation. 1037

23 OLD POST OFFICE BUILDING HSR Incompatible Paints: Understanding some basic differences in the strength of various paints helps to explain certain paint problems. Paints that dry to a stronger film are incompatible with those which are weaker. Acrylic latex paints are stronger than oil/alkyd paints. Oil or oil/alkyd paint is stronger than water based paint such as calcimine. When a stronger paint is applied over a weaker paint, it will tend to pull off any weaker paint which may have begun to lose its bond with its substrate. Thus, on many ceilings of older buildings where oil/alkyd paints have been applied over old calcimine, large strips of paint may be peeling. Inter coat Peeling: Can be the result of improper surface preparation prior to the last repainting. This most often occurs in protected areas such as eaves and covered porches because these surfaces do not receive a regular rinsing from rainfall, and salts from airborne pollutants thus accumulate on the surface. If not cleaned off, the new paint coat will not adhere properly and that layer will peel. Another common cause of inter coat peeling is incompatibility between paint types. Lead: In virtually all paints made before 1950, the white or hiding pigment was a lead compound, or more rarely, zinc oxide. Work to remove lead paint such as scraping and dry sanding releases the lead--a highly damaging heavy metal--in dust. Lead dust then enters the human system through pores of the skin and through the lungs. The use of heat for stripping also creates toxic lead fumes which can be inhaled. Metal Finishes: Paints marketed for use on metals, can either be alkyd, latex, or epoxy based, or combinations. The primers used for metals are formulated with rust inhibiting ingredients. Oil-based/alkyd paints: Nonvolatile oils and resins, with thinners. (Alkyds are synthetic, gelatinous resins compounded from acids and alcohol.) Accept almost any type of coloring/hiding pigments. For use on interior wood and metal. Orbital Sander: (Abrasive Method Mechanical) Designed as a finishing or smoothing tool - not for the removal of multiple layers of paint the orbital sander is thus recommended when limited paint removal is required prior to repainting. Because it sands in a small diameter circular motion (some models can also be switched to 1038

24 OLD POST OFFICE BUILDING HSR a back-and-forth vibrating action), this tool is particularly effective for feathering areas where paint has first been scraped. The abrasive surface varies from about 3x7 inches to 4x9 inches and sandpaper is attached either by clamps or sliding clips. A medium grit, open-coat aluminum oxide sandpaper should be used; fine sandpaper clogs up so quickly that it is ineffective for smoothing paint. Paint: A dispersion of small solid particles, usually crystalline, in a liquid medium. Applied to a surface, this liquid has the special quality of becoming a solid, protective film when it dries. Paint also enhances the appearance of surfaces. Paint Scraper: (Abrasive Method Manual) Paint scrapers are commonly available in 1-5/16, 2-1/2, and 3-1/2 inch widths and have replaceable blades. In addition, profiled scrapers can be made specifically for use on moldings. As opposed to the putty knife, the paint scraper is used in a pulling motion and works by raking the damaged areas of paint away. Peeling: Peeling to bare wood is most often caused by excess interior or exterior moisture that collects behind the paint film, thus impairing adhesion. Generally beginning as blisters, cracking and peeling occur as moisture causes the wood to swell, breaking the adhesion of the bottom layer. Pigment: Made the paint opaque, thus preventing deterioration of the substrate caused by ultraviolet light, and added color, thus making the paint attractive. White lead, a whitish corrosion product of lead, was most often used to provide opacity. The white pigment in a colored paint is often called the hiding pigment. In addition to preventing the sun s damaging rays from hitting the surface of the substrate, the white lead also helped prevent the growth of mold and mildew. Not until early in the 20th century was a successful substitute, titanium dioxide (TiO2), patented, and even then, it did not come into prevalent use by itself until the mid-20th century (earlier in the century, titanium oxide and white lead were often mixed). Zinc oxide was used briefly as a hiding pigment after Primer: It is the intermediary material between the immediate substrate, which may be an old paint layer or may be bare wood, plaster, or metal (rarely stone, as around 1039

25 OLD POST OFFICE BUILDING HSR a fireplace opening), and the fresh paint itself. The primer must be capable of being absorbed to some extent by the material underneath while being compatible and cohesive with the paint to be applied on top. Most paint manufacturers will provide explicit instructions about which primers are most compatible with their paints. Those instructions should be followed. Putty Knife: (Abrasive Method Manual) Scraping is usually accomplished with either a putty knife or a paint scraper, or both. Putty knives range in width from one to six inches and have a beveled edge. A putty knife is used in a pushing motion going under the paint and working from an area of loose paint toward the edge where the paint is still firmly adhered and, in effect, beveling the remaining layers so that as smooth a transition as possible is made between damaged and undamaged areas Rollers: Since all contemporary commercial paints dry with a smooth surface anyway, use of a roller or sprayer is acceptable for priming, and even for a first finish coat. However, to get paint well pushed into articulated surfaces and to add some texture to larger flat surfaces, a brush is best. Sanding Block: (Abrasive Method Manual) Blocks made of wood or hard rubber and covered with sandpaper are useful for hand-sanding flat surfaces. All sanding should be done with the grain. Sandpaper: (Abrasive Method Manual) After manually removing the damaged layer or layers by scraping, the uneven surface (due to the almost inevitable removal of varying numbers of paint layers in a given area) will need to be smoothed or feathered out prior to repainting. Hand sanding, as opposed to harsher mechanical sanding, is recommended if the area is relatively limited. A coarse grit, open-coat flint sandpaper useful for this purpose because, as the sandpaper clogs with paint it must be discarded and this process repeated until all layers adhere uniformly. Sanding Sponge: (Abrasive Method Manual) Rectangular sponges with an abrasive aggregate on their surfaces. Useful for hand-sanding detail work that requires reaching into grooves because the sponge easily conforms to curves and irregular surfaces. All sanding should be done with the grain. 1040

26 OLD POST OFFICE BUILDING HSR Solvent-base Strippers: (Chemical Method) The formulas tend to vary, but generally consist of combinations of organic solvents such as methylene chloride, isopropanol, toluol, xylol, and methanol; thickeners such as methyl cellulose; and various additives such as paraffin wax used to prevent the volatile solvents from evaporating before they have time to soak through multiple layers of paint. There are two important points to stress when using any solvent-base stripper: First, the vapors from the organic chemicals can be highly toxic if inhaled; skin contact is equally dangerous because the solvents can be absorbed; second, many solvent-base strippers are flammable. Solvent Blistering: The result of a less common application error, is not caused by moisture, but by the action of ambient heat on paint solvent or thinners in the paint film. If solvent-rich paint is applied in direct sunlight, the top surface can dry too quickly and, as a result, solvents become trapped beneath the dried paint film. When the solvent vaporizes, it forces its way through the paint film, resulting in surface blisters. This problem occurs more often with dark colored paints because darker colors absorb more heat than lighter ones. To distinguish between solvent blistering and blistering caused by moisture, a blister should be cut open. If another layer of paint is visible, then solvent blistering is likely the problem whereas if bare wood is revealed, moisture is probably to blame. Solvent blisters are generally small. Special finishes: Finishes such as urethane and epoxy-based paints, marketed for very high gloss surface treatments. Thermal: (Method of removing paint) Softening and raising the paint layers by applying heat followed by scraping and sanding. Generally used for total paint removal. Trompe L oeil: Painting technique that could replicate three-dimensional architectural detailing such as ornate molded plaster moldings, medallions, panels, and more. Vehicle: The fluid component was termed the vehicle, or medium, because it carried the pigment. Historically, vehicles included turpentine in oil paints and water in water based paints, but other vehicles were sometimes used, such as milk in casein paints. Volatile organic compounds (VOCs): Organic paint strippers, such as methylene 1041

27 OLD POST OFFICE BUILDING HSR chloride, and oil/alkyd paints have VOCs as their solvent base. Inhaling these fumes can lead to respiratory and other illnesses, and to cancer. Especially in closed spaces (but in the outdoor environment as well) these compounds pollute the air and can damage health. Wrinkling: This occurs when the top layer of paint dries before the layer underneath. The top layer of paint actually moves as the paint underneath is drying. Specific causes of wrinkling include: applying paint too thick; applying a second coat before the first one dries; inadequate brushing out; and painting in temperatures higher than recommended by the manufacturer. TYPES OF HISTORIC PAINTS Historic paints were often made with what was available, rather than adhering to strict formulas. Recipes for successful formulas can be found in historic documents, such as newspapers, illustrating the combinations of ingredients which could be used to produce a paint. Oil-based paints Linseed oil, a volatile thinner such as turpentine; a hiding pigment (usually white lead) and coloring pigments. Enamels: natural resin varnish was added to oil-based paint to provide a hard, more glossy surface. Glaze: a translucent layer applied to protect the paint and to impart a more uniform gloss surface. Usually made from linseed oil with natural resin varnish added. Some glazes have small quantities of tinting pigments such as verdigris or Prussian blue; some had no pigments added. Water-based paints Water, pigment, and a binder, such as hide glue, other natural glues, or gums. Usually used on interior plaster surfaces. Whitewash: often used on interior plaster surfaces in utilitarian spaces and, at times, 1042

28 OLD POST OFFICE BUILDING HSR used on interior beams; consisted of water, slaked lime, salt, and a variety of other materials. Occasionally a pigment (usually an ochre or other earth pigment) was added to provide tint or color. Distemper: used for interior applications, were made from water, glues (one or more different natural glues, gelatine, and gums) with whiting as the basic white pigment to which other tinting pigments were added. Calcimine, or kalsomine: often used on interior surfaces and is another common name for distemper. Tempera: paint prepared with pigment, egg yolk or white and water; used almost exclusively for decorative treatments. Gouache: a water based paint made of whiting, pigment, water, and gum arabic as the binder; used almost exclusively for decorative treatments. Milk-based paint Casein: also called milk paint, was made with hydrated (slaked) lime, pigment, and milk. Most often oil was added, making a strong emulsion paint. Various recipes call for a large variety of additives to increase durability. Casein paints were also used for exterior surfaces. GLOSSARY OF PLASTER TERMS Ceiling Medallion: Vernacular houses often used plain-run concentric circles from which lighting fixtures descended, usually hung from a wrought iron hook embedded in the central ceiling joist. More elaborate medallions were composed of shop-cast pieces, such as acanthus foliage often alternating with anthemia or other decorative designs. Medallions usually related stylistically to the cornice ornament found in the room and could be created with or without a plain-run surround. Coffered Ceiling: Coffering units were cast in the shop or on site, then installed with hanging wires to form the ceiling. Ceiling design varied from period to period as to depth, panel shape, and ornamental complexity. Not always flat, coffering is seen inside domes, within barrel vaults and groin ceilings, along overhead ribs and 1043

29 OLD POST OFFICE BUILDING HSR soffits. Rosettes are usually centered in the panels and often enrich the intersections of elaborate stiles bordering the panels. Flat ceiling coffers are generally identical in reflected plan; on domed or barrel ceilings, coffers differ from course to course so as to appear identical from various sight lines. The finish treatment of a coffered ceiling frequently exhibits the height of the painter s craft. Cornice: Consisted of plan moldings made from gypsum and lime run atop temporary lattice strips around the room. Tooling for plain-run moldings called for a sheet metal template of the molding profile mounted on a wooden horse. Mitering was accomplished using a plaster and lime putty gauge (mix) tooled with miter rods at the joints. Decorative enrichments such as leaves, egg and dart moldings, and bead and reel units were cast in the shop and applied to the plain runs using plaster as an adhesive. Painting, glazing, and even gilding followed. Gypsum Plaster: Gypsum begins to cure as soon as it is mixed with water. It sets in minutes and completely dries in two to three weeks. Historically, gypsum made a more rigid plaster and did not require a fibrous binder. However it is difficult to tell the difference between lime and gypsum plaster once the plaster has cured. Lath: A means of holding the plaster in place. Lime Plaster: Made from four ingredients: lime, aggregate, fiber, and water. The lime came from ground-and-heated limestone or oyster shells; the aggregate from sand; and the fiber from cattle or hog hair. Metal Lath: Metal lath, patented in England in 1797, began to be used in parts of the United States toward the end of the 19th century. The steel making up the metal lath contained many more spaces than wood lath had contained. These spaces increased the number of keys; metal lath was better able to hold plaster than wood lath had been. Models: Whether of capitals, cornices, medallions or cartouches, are made as whole units or in parts depending on project demands. Completeness, accurate dimensions, and attention to historic styles are essential ingredients of successful models. Each part of a model has a name, i.e., dentil, guilloche, rinceau or bolection molding, modillion, egg and dart. 1044