- aggregate: Mineral components (sand, stone, shell) added to mortar, plaster, or concrete. Aggregates are the strength reinforcement to mixture and it decreases shrinkage. The choice of aggregate for a mortar is directly related to particle size distribution, or the range of small to large and proportions thereof.
- alcohol-dilutable resin: A type/class of resin that can be solvent-cut so that they penetrate with ease but can still achieve strength, such as Eponex 1510. Benefit of this kind of resin is that it has very little appearance change to the material on which it is used.
- alluvium: Clay, silt, or gravel carried and deposited by a river or other running water. Typically made up of fine particles of silt and clay and larger particles of sand and gravel.
- antefixae: Vertical blocks of masonry used at the termination of roof tiles at the eave.
- architrave: The lower third or support beam or backband for doors and windows in an entablature.
- arris: The sharp edge created by the meeting of two surfaces, as in the corner or edge of a brick.
- astragal: A narrow molding with a semi-circular profile with flat planes (fillets) on either side. Often used as the center member of a double door or at glazing bars on cabinets and bookcases.
- attapulgite: A magnesium aluminum silicate clay of very fine particle size. Has needle-shaped crystals. Also known as palygorskite or Fuller’s Earth, it occurs naturally near Attapulgus, Georgia.
- barium chloride: A salt used as a test for sulfates, forming a white precipitate (barium sulfate)
- bead: A rounded shape cut into the square edge of trim or molding to soften the edge. Can be a smooth round surface or a carved surface.
- belt course: A wood or masonry band, either projecting or flush with the face of the building. Generally coincides with the masonry pockets of floors higher than the first. Walls usually reduce at belt course where the structural beams are inset; can be both decorative and structural.
- brace: Diagonal framing member that provides stiffness to keep plane (wall, table top, etc.) from racking by creating a triangle.
- calcareous: Lime-containing
- calcimine: An historic waterbased paint created from animal glue and lime (whiting or chalk, a non-reactive form of carbonate.)
- calcining: The process of controlled burning, of calcium carbonate (CaCO3) to drive off CO2 in order to create quicklme (CaO). Over burning the lime will melt the material thereby decreasing surface area. Correctly low fired lime is more coral-like & aerated, creating much more surface area, which is preferable.
- calcite: A carbonate mineral and the stable form of calcium carbonate. Calcite is the main mineral component in limestone and is found in the shells of clams and oysters. When calcium carbonate percipitates out of water it becomes calcite.
- calcium carbonate (CaCO3): Chemical compound commonly known as limestone, one of the steps in the lime cycle. Burned at a {{specific temperature}} for {{a set amount of time}} it will create quicklme (CaO), and slaked with water it will create hydrated lime [Ca(OH)2]
- calcium chloride (CaCl2): A salt created by reacting calcium carbonate (limestone) with hydrochloric acid (muriatic acid) commonly used as a de-icing salt because of its deliquescent nature, which allows it to keep water in a liquid state.
- calcium oxidide (CaO): Chemical compound commonly known as quicklime or lump lime; one of the steps in the lime cycle. The compound is created when calcium carbonate (CaCO3) is calcined. Calcining causes CO2 to separate from the calcium carbonate compound, leaving CaO.
- carbonation: When the lime (calcium hydroxide) in mortar or plaster is changed into a carbonate. Occurs when lime reacts with carbon dioxide from the air, releasing water through evaporation and forms calcium carbonate.
- Carbopol: A cross-linked polyacrylate (polymer of acrylic acid) elastomer used to thicken or gel a variety of aqueous and solvent preparations. These were originally developed for the cosmetics, paint, and pharmaceutical industries. In water-based preparations, Carbopol is often mixed with a base like NaOH, KOH, ammonia, or triethanolamine to produce a clear viscous gel; in solvents, complex “salts” of bases (“ethomeens”) with the polymer can form gel-like structures.
- casein: An extremely durable paint of crosslinked lime (calcium hydroxide or oxide) and milk that can further be made highly water-resistant and more durable by adding up to 5% raw linseed oil
- cementitious bond: In lime plastering or pointing, it is the intimate bonding of calcium hydroxide and water that is achieved through pressure. Failure to get sound cementitious bond between layers of plaster or mortar leads to delamination or two separate unconnected lifts.
- chamfer: A bevel, made by cutting off the edge of a corner (arris) of wood, masonry or other material.
- Chimney Lining Cone: This simple jobsite-built cone allows the deteriorated mortar on the inside of historic chimneys to be replaced rapidly. The cone is pulled up through the chimney flue with a rope on a wheelwell suspended from scaffolding above as thinned lime mortar is poured down onto it from above. In this way recessed mortar joints are pointed and the interior face of the chimney is parged in lime mortar, allowing the reuse of historic chimneys that might otherwise have been considered fire hazards due to mortar loss. Unlike popular modern ceramic and portland cement relining methods, this lime mortar treatment is compatible with porous historic brickwork. The soft rubber flippers on the bottom of the cone allow the cone to accommodate variability in the interior of the chimney, whether from irregular surfaces or from the flue narrowing as it rises. The cone has proven successful in relining both straight flues and those that curve as they rise out of the firebox and up through the smoke shelf. It takes about half a day to make a site-specific cone and reline the chimney. This method allows unstable chimneys that would otherwise be torn down and relaid to remain, saving both historic fabric and weeks worth of labor. If the rubber flippers are trimmed back, then they can also line the inside of chimney flue with a layer of lime mortar.
- compression fold: need definition
- consolidation: Strengthening a material by the use of various resins or epoxies. Deteriorated surfaces, such as the soft and punky surface of a window sash, can be consolidated with tongue oil, or alkyld resin. Weakened or rotted wood can be consolidated by the use of epoxy, which is drawn in then cures/hardens within the fibers of the wood strengthening and the wood.
- copal: A natural hard resin blended with drying oils (oleo-resinous) to produce varnishes, particularly for furniture and “coach” applications where high durability is required. Formed from fossilized plant extracts (e.g. formed under heat and pressure), the African “Zanzibar” form is the most durable.
- coping saw: Also known as a carpenter’s saw. Thin blade held in a U-shaped holder used to cut intricate shapes or cutouts. Often used to fit moldings together.
- coping: In wood: a process for joining pieces of wood with intricate profiles, such as cornice moldings. These joints are called “coped joints.” In masonry: The masonry course that caps a wall. Masonry units usually have a sloping top in order to shed water.
- cornice: Most commonly the top section of an entablature; can also be any projecting decorative molding running along the top of a wall or building.
- counterflashing: Metal that is anchored into a building and over the flashing coming up from the roof. Helps to prevent water infiltration. Often found where the a vertical face meets the roof.
- course: A row of bricks running horizontally.
- crossett: A rectangular breakout at the corners of windows, doors and mantles that creates a square which the molding (backband/architrave and in some cases frieze) wraps around.
- crown: The highest decorative molding on a door, window, wall, or cabinet.
- dammar: A plant resin drawn by tapping the Dipterocarpaceae tree of the East Indies. Predominantly blended with turpentine to produce spirit varnishes for coating paintings due to the clearness of the resin and its ability to saturate oil paints. Dammar has a lower tendency toward white “blooms” in high humidity than many other natural resins, and can be quite brittle as a coating material unless it is modified with the addition of small amounts of oils, waxes, etc.
- delamination: A mode of failure where bonded layers of a material separate. Both manmade and natural materials can delaminate. Wood, plaster, paint and even stone can delaminate. Stone delamination, similar to exfoliation, occurs along the natural bedding planes. This kind of deterioration can occur when layers of a stone are laid skyward instead of horizontally, when expansion and contraction occur due to trapped moisture in the stone, by the expansion of rusting metal embedded in the stone, or by weathering caused by harsh conditions.
- deliquescent: The property of becoming liquid on exposure to air or having the ability to pick up moisture up from the air, commonly attributed to salts that continue to remain wet and move through masonry walls in the wet state as the crystals continue to grow in size.
- double-ended striker: A masonry tool, used to press mortar into a joint during the pointing process.
- double-hung: Window formed of two panels, called sashes, one of which slides up past the other. Double-hung is the most common kind of sash window, comprised of two panels.
- dovetail joint: A locking structural joint, normally but not necessarily in wood. A wedge-shaped tenon that drops into a wedge-shaped mortise and locks in one direction, but not two.
- drift: A steel pin of a consistent diameter used to remove nails; pushes the nails through the substrate without creating a larger hole.
- drop: The ‘drop’ process is a coordinated proof-of-concept test. It executes each of the anticipated repairs on a building or site, testing both materials and methods in the real world. This allows for a refinement of the treatments and, if documented accurately and included in the bid package, removes discussion of whether the treatment can actually be done. By clearly describing the work that will be required, it helps the contractor estimate an appropriate cost. This initial drop is executed by the conservation team, in the process refining the approach and tightening up budget and time estimates. The process proves that their materials are available and can actually produce the desired results; in other words, that there is a reasonable real-world delivery mechanism to execute the treatment. A second drop comes after the contract has been awarded. It is in this phase that non- standard construction processes and materials are transferred to the contractor who must execute the bulk of the work still under the quality control of the conservators, who ultimately hold the purse strings. There are numerous benefits to the drop, beginning with definition of most of the underlying causes and development of solutions before bid packages are distributed and following through to the client having a more clearly defined budget based on real work on the building, not theory. It is a process that realizes most modern contracting documents and processes are designed for new construction and ill-equipped to accommodate the surprises that are common in working on existing buildings, particularly historic structures. The greatest benefit may be the elimination of the adversarial relationship that often develops between client, architect, conservator, and contractor because so many of the unknowns have been removed upfront.
- dry-fit: To fit a disassembled item back together without glueing or setting it permanently. A test-run or dry-run, meant to make sure that everything fits together snugly and properly. In furniture and decorative woodwork, there should be numerous dry-fits before adding adhesive for the final fit.
- dutchman: A patch fashioned of the same material or other compatible material as a damaged or incomplete piece shaped to fit seamlessly in a void or damaged area of the existing piece. For example, a brick dutchman is set into a piece of damaged brick. A wood repair in which a piece of wood is of an existing piece of wood
- efflorescence: Chalky residue deposited on the surface of masonry. After moisture in masonry is drawn to the surface by capillary action and the water has evaporated, concentrated powdery compounds such as salts or calcite are left on the surface. Often caused by chemical reactions of masonry components with chlorine in municipal water or acidic/basic cleaning solutions, all of which create salts which then deposit onto the surface.
- entablature: A horizontal band of layered room decoration, usually supported on columns or pedestals, and made up generally of three parts: architrave, frieze and cornice.
- Eponex 1510: An alcohol-dilutable resin.
- epoxy: A polymer resin that reacts with amine compounds to form a solid.
- ethomeen: Ethomeens are fatty amine derivatives of coconut triglyceride fatty acids (“Cocamines”). They are basic cationic surfactants (soaps) by themselves, but endless permutations of these materials have been made by additionally ethoxylating the amines (coupling ethylene oxide polymers to them) to produce a new class of surfactant molecules.
- exfoliation: A kind of masonry failure in which the stone separates in flakes or scales, usually due to salts or ice chrystals forming in a shallow planes just behind face. See delamination.
- expansion joint: The connection of metal sheets or pans that allows for the expansion and contraction of metal.
- filled-epoxy resin: An epoxy resin with some kind of material mixed in to thicken it, bulk it out. By making it thicker, less resin is used made to be more controlable. Filled-epoxy resin has high-viscosity and less shrinkage because there is less liquid to evaporate. Resin with ground gypsum can be used in high heat areas, like attics because it ups the heat resistance. Very high heat will soften resin, making it easy to remove. Some other fillers include: dirt, sawdust, phenolic or glass microballoon (ziospheres,) chopped cotton, graphite to give it more paste or putty-like consistent. By filling epoxy resins, they are made to be thixatropic, meaning it creates internal strength and weight is enough that it can stand up straight and can overcome the effects of gravity.
- fire skin: The outer surface of a brick heated more thoroughly and expected to weather better over time.
- flashing: A continuous piece of metal used to prevent water penetration in roofing systems. Usually found at an angle or joint like where the roof meets the chimney, under an expansion joint, and in the valley of a roof. Sometimes covered with “counterflashing” to provide extra protection against water infiltration.
- fluorescence microscopy: Fluorescence microscopy takes advantage of the ability of certain materials to absorb light at one wavelength and give it up or “fluoresce” the light at a longer wavelength to help characterize the constituent components of a material through routine microscopic examination. Fluorescent dyes, which carry reactive groups on them, have also been used in this regard to “tag” or make fluorescent certain common paint and varnish binding materials. Among these reactive dyes are Rhodamine B (which helps highlight oil-containing materials in paint and varnish samples); Alexafluor488 (which fluoresces proteins-containing layers); and TTC (triphenyltetrazolium chloride, which “tags” carbohydrates, such as gums).
- flush cut saw: A saw that has no set to its teeth, and will not scratch a surface when flush cutting.
- flute: Shallow grooves running vertically along a surface, most commonly a column or pilaster.
- frass: Debris and excrement produced by wood eating insects like termites.
- frieze: The broad central strip of repeating carved decoration in an entablature.
- frost-jacking: The cumulative displacement of or in objects caused by frost action, the freezing and thawing of moisture in a material.
- galleting: Pieces of stone chips set into pointing at a fairly regular interval. Believed to be a decorative feature but in some cases applied to facilitate stucco application.
- gambrel: A type of roof similar to a gable, but with two slopes on each side, the lower sloping at a steeper angle.
- Georgian: Georgian architecture is named for the reign of the British Kings George I-IV (1714-1830) and is recognized by symmetry and based on strict geometry with three-dimensional embellishments modeled on Greek and Roman antiquities.
- glauconitic: Glauconite is a greenish mineral of silicate hydrate. Often found in sand or aggregate deposits. Its softness can create problems: when a joint is slicked glauconite breaks down and acts as a pigment, causing joints to become a spotty green.
- glazing putty: A type of putty used to hold the glazing or glass in place in a window. Usually in a triangular shape sloping from glass to muntin, it also helps to shed water.
- glazing: Glass made to be set into panes, such as in windows.
- grade: The elevation of the soil where it meets the building.
- grading: Reducing the soil to a lower height; to move soil to create a gently sloping surface.
- grapevine joint: Term originated in mid-late 18th century. This joint tool is ridden along arris of brick, making an indentation into the joint.
- grout: A thin mortar, with small aggregate particles. Sometimes dispensed into mortar joints with a grout gun.
- harling: An ancient technique where the render is thinned with water to a soupy consistency, scooped up on a curved trowel and thrown against the masonry with considerable force to create a cratered surface.
- hawk: Also known as a mortarboard. A square board with a handle underneath; used by masons and plasterers to carry mortar or plaster.
- hem: The edge of sheet metal that have been folded back on itself. A hemmed piece of metal has significantly increased strength and rigidity.
- hydraulic: Describes a material that sets in or under water. Once water is added it will harden on its own, like portland cement or hydraulic lime.
- in situ: Latin phrase meaning “in place” refers to an object or material that is still in its original position, not having been removed or dismantled. Example: “window sash repair was completed in situ.”
- jack arch: A structural element in masonry that spans over an opening in the masonry, providing support. Alternate names are “flat arch” and “straight arch.”
- Jahn: Proprietary masonry compound made to imitate most kinds of masonry.
- jamb: The side member running vertically in an arch, doorway, or window. What a door is hinged to and what a sash window rides up and down in.
- jig: A device for guiding a tool through either machine or hand process. Can be used with hand tools and machine tool. By using a jig you can repeat precisely the same motion, which is necessary in production of multiple identical pieces.
- joist: The horizontal structural member that supports the floor above, traditionally laid full-length with one piece stretching from wall to wall. Its function is to load the walls with weight of the floors, transferring the weight downward. The flooring is typically nailed to the joists on top, and typically lath will be nailed to the bottom side of the joists, onto which the ceiling plaster, or lath is attached.
- ketone resin: Polycyclohexanone is a crystal-clear synthetic resin that can be dissolved in mineral spirits to produce a rapid-drying varnish that is resistant to yellowing in UV (though it tends toward yellowing in the absence of light); however these synthetic resins, such as Laropal, tend to be more brittle and risk oxidation over time that results in the need for aggressive polar solvent mixtures to remove.
- laminated wood: Sheets of wood veneer glued together to create a single thicker sheet of wood. Can be sheets of wood veneer or actual pieces of wood glued together.
- lath: A support for plaster. Now commonly constructed of expanded metal mesh, it was originally constructed of wood strips nominally a quarter-inch thick by 1.5″ wide and in lengths running perpendicular over several floor joists or wall studs with about a fingertips spacing in bewteen for plastering mortar to wrap around and through to provide a “mechanical key,” or hook, around the backside of the lath. There are two kinds of historic lath: riven and circular cut. Prior to the 1830s lath was riven from larger pieces of wood. After the 1830s, lath was cut with the circular saw, a new invention. Very useful for dating buildings or renovations.
- lift: An individual pass of mortar application into a masonry joint. Pointing a joint usually takes three lifts, the last being the pointing mortar. Modern term for one layer application of mortar in a joint. Often mentioned in conjuntion with a common construction edict “put in the next lift after its thumb print hard,” but basically this recommendation is a recipe for disaster.
- lintel: The structural member that spans an opening, generally doors or windows. In masonry buildings, lintels would have traditionally been wood or stone, but today in masonry buildings they are always steel or steel-reinforced concrete.
- lock seam: A type of metal joint that provides a mechanical connection and, when not soldered, allows for expansion and contraction of metal. A flat lock seam of sufficient width (3/4″ minimum) provides excellent watertightness. Also called a “compression seam.”
- MDO (Medium Density Overlay): High quiality exterior waterproof plywood with resin saturated paper face, good for making jigs or anything outdoors; machines nicely.
- mechanical connection: A connection of direct contact between two pieces. The joining of elements by fasteners, such as screws, bolts, or nails (instead of non-mechanical, meaning joining by adhesives.)
- mortise and tenon: A method of joining two pieces of wood together. Tenon is the piece that slides into the pocket, or mortise, of the other wood element. Mortise is the pocket created in one piece of wood to receive the tenon from the other piece. Sometimes called a “tenon pocket.”
- Moxon tool: Replica of an 18th century jointing tool designed based on drawings in Moxon’s Mechanick Exercises or the Doctrine of Handy-Works. The curved shape and rolling action used to create the line down the center of a joint creates a puffiness and fullness to the joint that is traditionally seen in Georgian joinery and cannot be achieved with any tool that is pushed or dragged.
- mullion: A vertical wood or stone that divides one window from another.
- muntin: The narrow vertical and horizontal woodwork inside window into which the glass sets.
- nailer: A wood strip, attached to a surface, used as a base for attaching another material such as roofing material or tread planks.
- naptha: A relatively low-volatility (low flammability and lower toxicity) petroleum distillate used as a slower-evaporating paint solvent (technically referred to as Varnish-maker’s and Painter’s Naptha, or VM&P)
- newel post: The base structural post for a staircase. The center pillar for a spiral staircase.
- niche: A curved wall recess with arched top used for ornamentation.
- nitrocellulose lacquer: A resin created by treating cotton or other cellulose products with nitric acid to produce solvent-soluble clear coating materials. It was found in the 1920s that this could produce a very durable, color-carrying lacquer. Used first as a paint to produce more than just black automobiles, it further found its way to other construction uses due to being the first easily sprayable quick-drying resin.
- oleo-resinous: A mixture of a resin with a drying oil (such as linseed oil that begins self-polymerizing at room temperature in reaction to oxygen), producing a glossy, hard surface that maintains some elasticity and thus durability.
- ovolo: A type of molding, rounded convex profile of a quarter section of a circle, sometimes carved with egg-and-dart design. Also called quarter-round.
- pan: A metal sheet with hemmed edges that lock together to create a water-shedding. Usually used as roof covering, flashing, or counterflashing.
- parging: A stucco interior or exterior treatment installed with the intention of addressing water problems.
- pilaster: A flattened column, attached to the wall.
- pintel: A metal pin or bolt used as the pivot for a hinge, usually inserted into a gudgeon.
- pit sawn: A pit saw was a two handled saw; often quite large (8-10′) While log is on support, one man stands on top of the log while the other stands in a pit. As men work down the log, the angle of the saw is constantly changing. This gives the lumber an irregular tool mark, making it easy to identify. Although commonly believed to have been phased out when circular saws were introduced, pit saws continued to be used in certain areas up until the late 19th century.
- plunge cut: Either by power or hand, a saw that cuts directly into a piece of wood without needing to start from an edge.
- ply: A individual layer, like in plywood or laminate.
- Pointing Guide: Simple pointing rig made out of angle iron, flat steel, and a few thumbscrews allows one mason to quickly set up his own straightedge to guide the curved pointing tool based on Joseph Moxon’s drawings. Traditionally, a straightedge of up to 12′ was used to create the illusion of uniformity and straightness in Georgian brickwork.
- pointing: A tooled finishing treatment applied to the mortar joints between brick or stone.
- portland cement: A generic term referring to modern hydraulic mortar, i.e. a mortar that when mixed with water will cure or harden. These are cements created by a multi-stage process that involves firing limes and clays until they are centered, or overcooked, to the point of rock-hardness. The clinkers that are created from this process are ground into fine powder. When water is added, a hydraulic set occurs. Because this is a manufactured process, the properties of a portland cement can be manipulated by changing the variables in the temperatures in which it is fired, the firing time, materials, etc.
- poultice: Absorbent, porous material soaked in a liquid that onto a surface to draw out salts or stains. When placed onto a surface the liquid is absorbed in, then porous material draws the liquid back out.
- proud: Describes an feature or element that is raised, not flush with the surface.
- PVA (polyvinyl alcohol): A water-soluble synthetic polymer. Used in conservation as an adhesive.
- quartz silica: Silica, or silicon dioxide, is most commonly found in the form of quartz. A very hard mineral known for its resistance to weathering is the most common as aggregate in mortar because it it ubiquitous in the environment.
- queen closer: A brick split in half lengthwise.
- rabbet: A rectangular notch or groove cut into an edge, so that a board, plank, or door may be fitted perpendicularly into it. Not to be confused with dado, which is cut further in from the edge. Also known as rebate.
- rail: Horizontal framing member in a window sash or a door. Used in conjunction with stiles, which are vertical, to complete the frame.
- relieve: To remove, carve wood.
- render: A type of stucco exclusively applied to masonry walls.
- repointing: The process of refilling a masonry joint with mortar after being cleaned and dressed properly. Mortar between bricks gradually erodes away from the face over time, and eventually repointing is required.
- resin: Amorphous substances, either solid or semisolid, that come from natural or synthetic sources. Used in lacquers, varnishes, adhesives, and synthetic plastics.
- sash sawn: A way of cutting wood using a vertical blade, single or ganged with multiple others. It reciprocates by animal or water power. Log is on a dog that is mechanically advancing log into blade, the same amount each time. Results in exactly parallel tool mark lines.
- sash: A frame of a window or door in which glass or panels are set.
- scribe: A tool with a sharpened metal tip, like an awl, used to mark wood, metal, etc. The act of marking a material with a scribe tool.
- shear: A kind of machine, either electrically or manually powered, that cuts metal and other materials.
- shellac: A natural resin formed from an annual exudation of the lac insect of southeast Asia, and India in particular, used for spirit varnishes (blended with alcohols). Shellac gives a hard surface that can be friction-polished to a very high gloss (french polish). Even when other preparations will be used for the finish surface, ethanol-cut shellac is commonly used to seal bare wood and raise the grain prior to a first sanding so that subsequent coatings will “take” evenly.
- silver nitrate: The product of silver reacted with nitric acid, it is used to react with substances presumed to contain chloride. The reaction of silver with a chloride produces a creamy white precipitate.
- skew chisel: A chisel with a symmetrical bevel and the cutting edge is not square to the sides of the tools.
- slaking: The process of reintroducing molecular water into fired (or calcined) lime.
- Sorbitan/Tween 20: Polysorbate 20 or Tween 20 is a neutral, non-ionic surfactant used in a number of domestic, scientific, and pharmacological applications. As a surfactant its structure has both a hydrophilic (water-soluble) portion to its structure (sorbitol, a common sugar, and short ethoxylate groups) and a hydrophobic (non-water soluble) portion (lauric acid). Because it is based on natural components like sugars and fatty acids it is often used in food applications, as well as generally being a useful emulsifier for oil in water, etc.
- spirit varnish: Varnishes that rely on fast-drying alcohol for their set, and thus require fast work on the part of an applicator. Examples of resins for spirit varnish are shellac and dammar.
- spline: A thin strip of wood that helps to align and join pieces of wood; forms part of mechanical joint connection by increasing surface area of joint.
- steam chase: A channel cut into the wall to route steam pipes.
- stile: Vertical framing member in a window sash or door. Used in conjunction with rails, which are horizontal, to complete the frame.
- stoddard solvent: This petroleum distillate is comparatively less toxic than many other paint-related solvents. It also has a slow rate of evaporation providing considerable “open” or working time before skinning or film creation when used as a thinner.
- stratigraphy: Study of the sequence (chronology) and condition of layers to understand the history of a material.
- striking: Packing mortar into joints between masonry. When working with lime mortar, the use of pressure in packing the mortar into the joint instead of slicking the joint creates a strong cementitious bond.
- sulfate crusts: Gypsum deposits on the surface of a material resulting from the reaction of atmospheric sulfuric acid with lime-bound materials.
- thermoplastic resin: Resin that will soften with heat, like filled-epoxy resin.
- thermosetting: A resin with a heat-initiated set.
- TPO: Thermoplastic Olefin, constructed from ethylene propylene rubber. Used in roofing as a water barrier. Because it is heat weldable it has many other applications and it can be quickly shaped into a custom mold or reservoir.
- transom: A window sash found over a door to let light in.
- triage: A process for sorting items by the types of deterioration, their severity and quantity. Triage often makes the repair process more efficient when dealing in multiples of the same object or material by allowing custom repairs to be made en masse. For example in repairing multiple windows, rotted mortises from all windows can be batched together and treated all at once with a single mixture of consolidation.
- verdigris: Copper salt, of various types. Also referred to as Copper(II) acetate. For centuries has been used as paint pigment for its blue/green color and as a fungicide. Different areas will have different kinds of salt: coastal will usually have more sodium chloride because of the ocean, urban/industrial areas will have more complex salts.
- watertable: A horizontal shelf with skyward facing joints that steps out on the base of the building. Helps to shed water away from base of building. Generally coincides with the masonry pockets of the first floor joists on the interior. Traditionally this also coincides with the narrowing of the foundation width from a foundation thickness to a wall thickness.
- white lead: (PbCO3)2 Pb(OH)2 Pigment that was used in lead paint because of it opacity. A mixture of the carbonate and the hydrated oxides of lead. Also known as “flake white.”
- wythe: The horizontal interior-to-exterior number of rows of bricks in a wall. For example, an 18″ thick foundation wall would be four thicknesses of approximately 4″ bricks with mortar between each. In contrast, the vertical rows of bricks are called courses.
- xylene: A coal tar distillate of benzene, this aromatic (sweet-smelling) solvent is used for thinning paints and is less volatile and slower evaporating than toluene.
- zeolitic: A class of hydrated aluminum silicates (aluminosilicates) of calcium, sodium, magnesium, or potassium with a micro-porous structure. Types of zeolites include attapulgites.
Sources Cited
Preservation Science, Terms & Tools, Accessed July 6, 2019.
Key Facts
At time of upload on January 6, 2021: