ACCELERATOR—Any material added to Portland Cement Plaster which speeds up the natural set.
ACCESSORIES—Any formed or fabricated metal used in the production of a Plastered surface
ADDITIVE—an admixture which is added to a product at the mill during manufacture.
ADMIXTURE—A material other than water, aggregate or basic cementitious material that is used as an ingredient of plaster and is added to the batch immediately before or during its mixing for the purpose of improving flow and workability or imparting particular qualities to the plaster.
AGGREGATE—Inert graded material, such as sand, vermiculite or perlite, around which cement paste encapsulates and binds to produce cement plaster.
AIR ENTRAINMENT—Intentionally introducing into Portland Cement during the mixing process a number of minute air bubbles distributed throughout the mass to improve workability, and plasticity. It is believed to reduce the freeze-thaw cracking.
ARRIS—A sharp clean angle forming an external corner where two surfaces meet.
ATOMIZER—A device that introduces air into material at the nozzle during machine application to establish and regulate the texture of plaster.
BASECOAT—The plaster coat or combination of coats to which a finish coat is applied.
BEVEL—a slanted surface
BLISTER—Protuberance in a coat of plaster caused by application over a moisture laden surface or troweling too soon over a moisture laden surface, or other causes.
BOND—Mechanical bond is the physical keying of plaster to a surface or lath or another coat of plaster.
Chemical bond is the adherence of one surface to another through fusion or interlocking on a molecular level through crystallization.
BONDING AGENT—A non-oxidizing, non-crystallizing, resinous water emulsion providing bond for plaster to concrete, masonry, or to prepare old plaster for re-stucco
BREAK—an interruption in the continuity of a plastered surface
BRIDGING—formed metal sized to fit inside steel stud flanges to stabilize construction
BROWN COAT—The coat of plaster directly beneath the finish coat. The leveling coat applied over the scratch (first) coat.
BUCKLES—Raised spots in plaster where the bond has been broken
BULL NOSE—An internal or external corner rounded to eliminate a sharp angle.
BUTTERFLIES—Color imperfections in lime based finishes
BUTTERFLY REINFORCEMENT—Strips of metal or nylon mesh reinforcement placed diagonally over the plaster base at the corners of openings prior to or during plastering
CALCINE, OR CALCINING—to make powdery or to oxidize by removing chemically combined water by the addition of controlled heat.
CASING BEAD—sometimes called J-mold or plaster stop. An accessory that encases plaster.
CAT FACE—a detail in semi-smooth plaster finish, or an unfinished detail in smooth trowelled finish.
CEILINGS—CONTACT CEILINGS—Lath and plaster secured in direct contact with the construction above.
CEILINGS—FURRED CEILINGS—Lath and plaster attached to steel channels, or furring strips attached to the construction above.
CEILING—SUSPENDED CEILINGS—Lath and plaster suspended from and not in contact with the floor and walls in construction.
CEMENT—A material or mixture of materials which, when in a plastic state, possesses adhesive and cohesive properties and which will set in place.
CHAMFER—A beveled edge
CHANNELS—Hot-rolled or cold-rolled steel used for furring and carrying channels or runners.
CHANNELS, CARRYING—The heaviest integral supporting member in a suspended ceiling.
CHANNELS, FURRING—The smaller horizontal member of a suspended ceiling, applied at right angles to the underside of carrying channels.
CHECK CRACKS—Random cracks in plaster caused by rapid evaporation of moisture, sometimes called craze cracks, alligator cracks or map cracks.
CHIP CRACKS—Similar to check cracks, except that the bond has been partially broken, sometimes referred to as egg-shelling.
COAT—A thickness or covering of plaster applied in a single operation. SCRATCH COAT, BROWN COAT, FINISH COAT.
CONSISTENCY—The degree of viscosity or plasticity of a pre-set mixed plaster.
CONTROL JOINT—An accessory installed to control the application of plaster.
CORNER BEAD—An accessory installed to provide a metal reinforcement at an arris or outside corner.
CROSS SCRATCHING—scoring or scratching a plaster scratch coat in two directions. Normally done on a ceiling to provide a more secure mechanical bond for the brown coat.
CURING—A process of maintaining moisture in plaster, either by preventing too rapid a loss of moisture or by adding moisture back into the plaster during the hydration process. The chemical process by which the plaster gains its strength.
DARBY—A flat tool approximately 4” wide and 42” long, used to smooth and level the brown coat prior to rodding or floating.
DASH BOND COAT—A thick slurry of Portland Cement, sand and water, dashed (blown or thrown) on concrete or masonry surfaces to provide a mechanical bond for the succeeding plaster coat.
DOPE—A term used to define any mortar additives such as those used to accelerate or retard the set of the plaster.
DOT—A small projection of basecoat plaster placed on a surface and faced out between grounds to establish the proper plaster thickness. Wood, steel, metal, plastic can be used in conjunction with plaster.
DOUBLE-UP OR DOUBLE-BACK—A method of applying plaster that allows for greater control of the suction and the plaster.
EFFLORESCENCE— Dried soluble-salts delivered to the surface of a cementitious product through moisture migration.
EXPANDED METAL LATH—Sheets of metal slit and expanded to form small diamond-shaped openings
EXPANSION JOINT—A method of minimizing stress relative to crack control in plaster
Especially useful when plaster is continuous over dissimilar materials.
FAT- Material accumulated on the trowel during the finish coat operation used to fill small imperfections.
FEATHEREDGE—see ROD—An edged tool used to cut excess plaster during the leveling process of a brown coat.
FIBER—material used to reinforce a plaster matrix. Horsehair, sisal, fiberglass
FINES—Aggregate particles with a high percentage passing the No. 200 sieve.
FINISH COAT—Final coat of plaster
FIREPROOFING—The application of fire-resistive materials direct to structural members to protect them from fire damage.
FLASHING—Integrating material between plaster systems and roof, window and door systems to provide waterproofing.
FLOAT—a method of preparing the brown coat. A method of texturing a finish coat. Tools to accomplish the process. Hard rubber, wood shingles, carpet, cork, felt, sponge, plastic, steel can be used.
FLOATING—A process of trimming, flattening, and filling voids in a brown coat as preparation for a finish coat. A process of bringing aggregate to the surface in a finish coat. Sand Floating or Floating the finish coat
FURRING—Members in Wall & Ceiling Construction beyond the normal plane or the material used in such construction.
GAUGING—The process of mixing gauging plaster or Keene’s cement with lime putty or Type S Hydrated Lime to provide strength to the finish.
GRADATION—The particle size distribution of aggregate as determined by separation with standardized sieve screens.
GREEN PLASTER—Plaster that has set but still retains moisture and is not fully hydrated.
GROUNDS—Wood or metal trim used to establish and determine the thickness of a plaster plane.
HANGERS—Vertical members which carry the steel framework of a suspended ceiling.
HARDENING—The process of gaining strength through hydration after plaster has set.
HAWK—A square tool, with a handle used by plasterers to carry plaster.
KEY—The result of lath embedment during the scratch coat process. The mechanical bond of a brown coat to a scored scratch coat. The result of attachment to a scored, perforated or irregular surface.
LATH—A base to receive plaster. Wood lath, wire lath, gypsum lath, expanded metal lath, welded wire lath, etc.
MASKING—The process of protecting adjacent work or products or material with paper or plastic.
MECHANICAL APPLICATION—Applying plaster by means of a pump, as distinguished from a Hawk and Trowel.
METAL LATH—EXPANDED—Also called Expanded Metal Lath, Sheet Lath, Rib Lath. Metal Lath is slit and expanded, or slit, punched or otherwise formed, with or without partial expansion, from copper alloy or glavanized steel coils or sheets.
a. Diamond Mesh or Flat Expanded Metal Lath—2.5 lbs/sq. yard or 3.4 lbs./sq. yard; painted or galvanized.
b. Self-Furring Metal Lath—A metal lath formed with dimples or horizontal ridges to extend the field of the lath a minimum ¼” from the face of the underlayment to which it is attached. The measurement is from the face of the paper to the bottom of the lath.
c. Flat rib Metal Lath—a combination of expanded metal lath and metal ribs which provides a fur of approximately 1/8”.
d. 3/8” Rib Metal Lath—a combination of expanded metal lath and ribs providing a depth of approximately 3/8”, in weights of 3.4 lbs/sq. yard or 4.0 lbs/sq. yard.
e. ¾” Rib Metal Lath—a combination of expanded metal lath and ribs of a depth of approximately ¾”.
f. Paper-backed Metal Lath—a factory assembled combination of any of the sheet lath with paper, the assembly being used as a plaster base.
MITER—The diagonal joining of two or more moldings at their intersection. The process of developing the diagonal joining.
MOIST CURE—See CURING
NOZZLE—An attachment at the end of a plastering machine hose to regulate the pattern of application.
ORIFICE—A Changeable Attachment to the nozzle which establishes the spray pattern of the plaster as it is blown onto the surface being plastered.
PERLITE—A Siliceous volcanic glass properly expanded by heat used as a lightweight aggregate in plaster.
PLASTER—A cementitious material or combination of same and aggregates that when mixed with water, forms a plastic mass which, when applied to a surface adheres, sets, hardens and preserves in a solid state the form imposed during the plastic state.
PLASTER PUMP—A machine to convey and deposit plaster in place.
PLASTIC CEMENT—Portland Cement to which plasticizing agents have been added during manufacture.
PORTLAND CEMENT PLASTER—A mix in which Portland Cement is used as the cementitious material. Usually applied on exterior surfaces or interior areas where moist conditions will exist or interior moisture is created.
PUDDLING—A condition caused by holding the nozzle too long in one place during the application of a dash coat finish.
PUMICE—A plaster aggregate made from lightweight volcanic rock.
PUTTY COAT—A troweled finish coat composed of lime putty or Type “S” hydrated lime gauged with gypsum gauging plaster.
RETARDER—Any material added to plaster to slow up it’s natural set. Cream of Tarter or pulverized glue will retard the set of gypsum plaster
RETEMPER—Addition of water to Portland Cement Plaster after mixing but before the set. Stucco after mixing has an initial set. Retempering after the initial set allows the material to have a longer second set time for additional spreadability.
ROCK GUN—A device for applying aggregate onto a bedding coat in production of marblecrete.
SADDLE TIE—A specific method of wrapping hanger wire around main runners, also for wrapping tie wire around the juncture of main runner and cross furring.
SCAGLIOLA—An imitation marble, usually precast, made of keene’s cement.
SCORING—Grooving, normally horizontal, of portland cement plaster scratch coats to provide a mechanical bond for the brown coat, and to maintain water in the scratch coat during the hydration process. A decorative grooving in the finish.
SCRATCH COAT—the first coat of plaster.
SCREEDS—Shapes attached to a framing member or plaster base before plaster application to establish plaster thickness and a straight plane. Plaster screeds are narrow strips of mortar applied on a wall or ceiling to establish thickness and plane.
SET—The change in plaster from a plastic state to a solid state.
SGRAFFITO-A Proceduce for decorative purposes generally consisting of two or more layers of differently colored plaster.
SHIELDING—The method of protecting adjacent work by positioning temporary sheets of rigid material during machine application of plaster.
SLAKING—The act of adding water to quicklime to produce hydrated lime or lime putty.
SOFFIT—The underside of a horizontal condition on a building.
SPRAY TEXTURE—a plaster finish by machine applying a finish coat of material.
STIFFENER—A horizontal metal shape tied to vertical members (studs or channels) of walls to brace them. A Bridge.
STRAIGHT EDGE—A true flat tool or rod, used to straighten the brown coat or plaster screeds.
STRING WIRE—LINE WIRE—Steel wire placed horizontally around a building of open stud construction to support paper backing, weather resistive paper and plaster base.
STRIP LATH—Strips of expanded metal lath used diagonally to reinforce door and window openings and other locations to reinforce plaster subject to localized stress.
STUCCO—Mortar used for exterior portland cement plaster finish.
SUCTION—The absorptive quality of surfaces, a dry plaster scratch coat or brown coat will have more suction than a moist surface. Killing the suction allows control over the application of plaster.
SWEAT OUT—Soft or damp gypsum plaster caused by poor drying conditions which delay or impede setting of plaster
TAPE—A plaster reinforcing mesh or paper used to reinforce angles and bridge lath joints in Veneer Plaster.
TEMPER—Mixing plaster to a workable plastic mass
TEMPLATE—A gauge, pattern or mold used as a guide to produce repetitive thickness or shapes.
THERMAL SHOCK—Stress created by an extreme change in temperature that may result in cracking of plaster.
THREE-COAT PLASTER—The application of plaster in three successive coats, leaving time between coats for setting and hydrating.
TURTLE BACK—A blister caused from over trowelling the surface with too much moisture in the basecoat.
TWO-COAT PLASTER—The application of plaster in two successive coats. Seen over masonry block, concrete, or other solid bases, seen over foam and 20 gauge wire in residential construction.
VERMICULITE—A lightweight aggregate in plaster
WASH-OUT—Lack of development of texture in machine dash finish caused by too thin a mix.
WATER—PROOF CEMENT—Portland cement to which waterproofing agents, have been added at time of blending materials at the mill.
WELDED WIRE FABRIC LATH—A plaster reinforcement of soft annealed wire, electrically welded at all intersections forming openings into which the plaster is keyed.
WOVEN WIRE LATH—A plaster reinforcement of zinc-coated wire, woven in openings, either flat or furred, into which the plaster is keyed.
Q: How long does stucco last on a building?
Q: What kind of fire rating does plaster provide?
Q: Does stucco over concrete masonry provide good resistance to wind-driven rain?
Q: Is stucco suited for use in a coastal environment?
Stucco Frequently Asked Questions
Q: Can I paint stucco to get the color I want?
Q: What is a fog coat?
Q: How do you create ornamental shapes on plaster surfaces?
Q: Can stucco, portland cement plaster, be cleaned, and if so, what methods should be used?
Q: What are common stucco finish textures? Is there anywhere to view them?
Q: What is the proper spacing for contraction/expansion joints in stucco applications?
Q: Does the type of joint in plaster affect its spacing or location?
Q: In a stucco frame-wall assembly, what purpose does building paper serve?
Q: What is the correct thickness of stucco?
Q: Are there restrictions on plastering at lower temperatures?
Q: Is it necessary to use a bonding agent with stucco?
Q: Does stucco require curing, and if it does, how is this best accomplished?
Q: How is stucco applied over insulating concrete forms (ICFs)?
Q: Can stucco be applied directly over painted brick?
Q: Plaster is placed in two or three layers, or “coats.” Are there guidelines or restrictions on placing each successive coat?
Q: What is the installed weight of stucco?
Q: Are there deflection limits for the structural backup for stucco?
When you see a Hart Plastering, Inc., sign on a job, you will know that a happy customer referred us because of our quality, our reliability and our unsurpassed service.