Roofing Article

A

Acrylic Coating: A coating system with an acrylic resin base.
Acrylic Resin: Polymers of acrylic or methacrylic monomers often used as a latex base for coating systems.
Aggregate: A surfacing or ballast for a roof system. Aggregate can be rock, stone, crushed stone or slag, water-worn gravel, crushed lava rock or marble chips.
Air Blown Asphalt: Asphalt produced by blowing air through molten asphalt held at an elevated temperature. This procedure is used to modify properties of the asphalt.
Aluminized Steel: Sheet steel with a thin aluminum coating on the surface to enhance the steel's ability to withstand weathering.
Aluminum: A non-rusting metal used in roofing for metal roofing and the fabrication of gutter and flashings.
Apron Flashing: A flashing located at the low end of a curb or penetration.
Architectural Panel: A metal roof panel that usually requires solid decking underneath.
Architectural Shingle: Shingle that provides a dimensional appearance. See also Dimensional Shingle.
Asbestos: An incombustible fibrous mineral form of magnesium silicate formerly used for fireproofing and sometimes used for the reinforcement of roofing materials.
Asphalt: A substance left as a residue after evaporating or otherwise processing crude oil or petroleum. Asphalt can be refined to conform to various roofing grade specifications:
* Dead-Level Asphalt: A roofing asphalt conforming to the requirements of ASTM Specification D 312, Type I. This asphalt is for use in roofs which do not exceed a ¼ in 12 slope (2%).
* Flat Asphalt: A roofing asphalt conforming to the requirements of ASTM Specification D 312, Type II. This asphalt is for use in roofs which do not exceed a ½ in 12 slope (4%).
* Steep Asphalt: A roofing asphalt conforming to the requirements of ASTM Specification D 312, Type III. This asphalt is for use in roofs which do not exceed a 3 in 12 slope (25%).
* Special Steep Asphalt: A roofing asphalt conforming to the requirements of ASTM Specification D 312, Type IV. This asphalt is for use in roofs which do not exceed a 6 in 12 slope (50%).
Asphalt Emulsion: A mixture of asphalt particles and an emulsifying agent such as bentonite clay and water.
Asphalt Felt: An asphalt-saturated and/or an asphalt-coated felt membrane. (See also Felt.)
Asphalt Primer: See Primer.
Asphalt Roof Cement: The proper name for Plastic Cement and Flashing Cement. Asphalt roof cement consists of solvent-based bitumen, mineral stabilizers, and other fibers (sometimes asbestos). Asphalt roof cement is categorized by ASTM standard D 2822-91 (1997) or for non-asbestos, ASTM standard D 4586-93.
* Plastic Cement is for use on low-slope surfaces, conforms to ASTM Specification D 312, Type I; Specification D 449, Types I or II; or Specification D 946. Plastic Cement is self-sealing, adhesive and ductile and is classified by ASTM Standard D 2822-91 Asphalt Roof Cement, and D 4586-92 Asphalt Roof Cement, Asbestos-Free, Types I and II.
* Flashing Cement can be used on vertical surfaces and has a high softening point, low ductility and conforms to the requirement of ASTM Specification D 312, Types II or III; or Specification D 449, Type III.
Atactic Polypropylene: A group of high molecular weight polymers formed by the polymerization of propylene.

B

Back-Surfacing: A fine mineral material on the back side of roofing materials such as roll roofing to keep them from sticking together while packaged.
Ballast: A material installed over the top of a roof membrane to help hold it in place. Ballasts are loose laid and can consist of aggregate, or concrete pavers.
Base Flashing (membrane base flashing): Plies of roof membrane material used to seal a roof at the vertical plane intersections, such as at a roof-wall and roof-curb junctures. (See also Flashing.)
Base Ply: The primary ply of roofing material in a roof system.
Base Sheet: An asphalt-impregnated, or coated felt used as the first ply in some built-up and modified bitumen roof systems.
Bitumen: Any of various flammable mixtures of hydrocarbons and other substances, occurring naturally or obtained by distillation from coal or petroleum, that are a component of asphalt and tar and are used for surfacing roads and for waterproofing.
Bitumen-Stop: A continuous seal for preventing bitumen from leaking down into or off a building. Is constructed by extending the base sheet or other non-porous ply of felt beyond the edge of the field plies. It is then turned back onto the top of the system and adhered. See also Envelope.
Bituminous Emulsion: Bituminous particles suspended in water or other solution. See also Asphalt Emulsion.
Blown Asphalt: See Air Blown Asphalt.
Built-Up Roof Membrane: A roof membrane consisting of layers of bitumen, which serves as the waterproofing component, with plies of reinforcement fabric installed between each layer. The reinforcement material can consist of bitumen-saturated felt, coated felt, polyester felt or other fabrics. A surfacing is generally applied and can be asphalt, aggregate, emulsion or a granule-surfaced cap sheet.
Butadiene: A colorless, highly flammable hydrocarbon, C4H6, obtained from petroleum and used in the manufacture of synthetic rubber.
Butyl: A hydrocarbon radical, C4H9. Butyl has a rubber-like consistency, is formed from the copolymerization of isobutylene and isoprene and is used primarily in sealants and adhesives.
Butyl Rubber: A butyl-based, synthetic elastomer.
Butyl Tape: A sealant tape used in numerous sealant applications such as sealing sheet metal joints.

C

Caulk: A material with no elastomeric properties used for sealing joints.
Caulking: The act of sealing a joint or of material.
Cellulose: A complex carbohydrate, (C6H10O5)n, that is composed of glucose units, forms the main constituent of the cell wall in most plants, and is used in the manufacturing of organic roofing materials.
Channel Flashing: Flashing with a built-in channel for runoff; used where roof planes intersect other vertical planes.
Chlorinated Polyethylene1 (CPE): CPE is a flexible material with high tear strength, good chemical resistance and patency towards UV radiation. As a result of the high chlorine content (typically 30%) it is inherently difficult to ignite, but releases hydrogen chloride during combustion. It suffers from an extremely high permeability to gas. Resistance to most inorganic chemicals is generally good, while resistance to hydrocarbons increases with increasing chorine content. The material is used mainly as an impact modifier for PVC and, to a lesser extent, LDPE and HDPE film.
Chlorosulfonated Polyethylene (NRCA Definition): A synthetic, rubber-like thermoset material, based on high molecular weight polyethylene with suphonyl chloride, usually formulated to produce a self-vulcanizing membrane. Chlorosulfonated Polyethylene or CSPE. Best know as Hypalon™, it was developed in 1951 by DuPont.
Chopped Glass and Emulsion (CG&E): A roof coating that consists of asphalt or clay emulsion and glass fiber reinforcement. The glass fiber comes in rope form and is mechanically chopped into small pieces and then mixed with the emulsion at the end of the spray gun so that the mixture is complete by the time the surfacing hits the top of the roof. Standard mixture is 9 gallons of emulsion and 3 pounds of glass fiber for every 100 square feet (36.5 Liters of emulsion and 1.5 kg of chopped glass for every 10 square meters). The CG&E coating is then usually surfaced with a fibered aluminum roof coating at rate of 1.5 gallons per 100 square feet (6 Liters per 10 square meters).
Coal Tar Bitumen: A proprietary trade name for Type III coal tar used in dead-level or low-slope built-up roofs. It is not for use in roofs exceeding ¼" in 12" (2%) slope.
Coal Tar Pitch: A type of coal tar used in dead-level or low-slope built-up roofs. It is not for use in roofs exceeding ¼" in 12" (2%) slope.
Coal Tar Felt: A roofing membrane saturated with refined coal tar.
Coal Tar Roof Cement: A trowelable mixture of processed coal tar base, solvents, mineral fillers and/or fibers.
Coated Base Sheet: An asphalt-saturated base sheet membrane later coated with harder, more viscous asphalt, thereby increasing its impermeability to moisture.
Coated Felt: An asphalt-saturated ply sheet that has also been coated on both sides with harder, more viscous asphalt.
Composition Shingle: A type of shingle used in steep-slope roofing and generally comprised of weathering-grade asphalt, a fiber glass reinforcing mat, an adhesive strip, and mineral granules.
Compounded Thermoplastics1 (NRCA Definition): A category of roofing membranes made by blending thermoplastic resins with plasticizers, various modifiers, stabilizers, flame retardants, UV absorbers, fungicides, and other proprietary substances, alloyed with proprietary organic polymers. Some of the membranes listed in this generic category are CPA, EIP, NBP, and TPA.
Contact Cements: Adhesives used to adhere or bond roofing components.
Copper: A reddish-brown element that conducts heat and electricity very well. It is also used as a primary roof material as well as a flashing component. Copper turns a greenish color after being exposed to the weather for a length of time and appears in the middle of the Galvanic Series.
Counterflashing: Formed metal sheeting secured to walls, curbs, or other surfaces, for use in protecting the top edge of base flashings from exposure to weather.
Cutback: Bitumen thinned by solvents that is used in cold-process roofing adhesives, roof cements, and roof coatings.

D

Dead-Level Asphalt: A roofing asphalt conforming to the requirements of ASTM Specification D 312, Type I. This asphalt is for use in roofs which do not exceed a ¼ in 12 slope (2%).
Dimensional Shingle: A shingle that is textured, or laminated to produce a three-dimensional effect. Also known as Laminated and Architectural Shingles. Please be aware that there are also shingles being produced that can be classified as Dimensional but not as Laminated. These shingles are comprised of a single piece of material rather than two different materials laminated together.

E

Elastomer: A material which, after being stretched, will return to its original shape.
Elastomeric: Properties of a material that will permit it to return to its original shape after being stretched.
Elastomeric Coating: A coating that can be stretched to twice its dimensions and that will return to original when tension is released.
Elongation: The ability of a material to be stretched or lengthened.
Emulsion: Fine particles suspended in a liquid solution. See also Asphalt Emulsion and Bituminous Emulsion.
Epichlorohydrin (ECH): A synthetic rubber material similar to EPDM with a stronger resistance to animal fats and oils than EPDM.
Epoxy: A type of synthetic, thermosetting resins that produce tough, hard, chemical-resistant coatings and adhesives.
Equipment Screen: A nonstructural wall or screen constructed around rooftop equipment such as HVAC units, curbs, etc. to hide the look of the equipment and make the structure more aesthetically pleasing.
Ethylene Propylene Diene Monomer (EPDM): A thermoplastic rubber with high tear strength that can be cross-linked by both peroxides and sulfur.

F

Felt: A roofing sheet made of interwoven fibers. The fibers can be wood or vegetable for Organic Felts, glass fibers for fiberglass felts, polyester, or asbestos.
Fiberglass Insulation: Insulation composed of glass fibers used to insulate walls and roofs. It can be rigid board or blanket insulation.
Film: A membrane or sheeting material with a nominal thickness of 10 mils or less.
Film Thickness: The thickness of a membrane or coating that is expressed in mils (thousandths of an inch). See also Wet Film Thickness and Dry Film Thickness.
Fine Mineral-Surfacing: A fine mineral material on the surface of roofing materials to prevent them from sticking to surfaces. 50% of this material has to pass through a sieve with holes that are 1/35" in size (#35 sieve).
Flashing Cement: A trowelable mixture of solvent-based bitumen and mineral stabilizers. Flashing cement that may contain asbestos stabilizers is categorized by ASTM standard D 2822-91 (1997) or for non-asbestos, ASTM standard D 4586-93. Flashing Cement is the term for Asphalt Roof Cement that can be used on vertical surfaces and has a high softening point, low ductility and conforms to the requirement of ASTM Specification D 312, Types II or III; or Specification D 449, Type III. See also Asphalt Roof Cement and Plastic Cement.
Fleece: Mats or felts used as a membrane backer and composed of fibers.
Flood Coat: The surfacing layer of bitumen into which aggregate is embedded on an aggregate-surfaced built-up roof. A flood coat is applied at an approximate rate of 45 to 60 pounds per square (100 square feet).
Fluid-Applied Elastomer: A liquid elastomeric material that cures to form a continuous waterproofing membrane.
Foam Stop: The edge metal used to terminate Sprayed Polyurethane Foam.

G

Galvalume: Trade name for a protective coating composed of aluminum zinc.
Galvanized Steel: Steel that is coated with zinc to aid in corrosion resistance. Galvanized steel for use in roofing should be Hot-Dipped Galvanized with a G-90 coating.
Glass Felt: (1)In the manufacturing of roofing materials - a sheet comprised of bonded glass fibers prior to being saturated with bitumen; (2) short for asphalt or coal tar saturated fiberglass felt membrane.
Glaze Coat: (1) The uppermost layer of asphalt on a smooth-surfaced built-up roof membrane, usually a reflective surfacing is installed over it; (2) A thin coat of bitumen applied to help protect the roof membrane when application of additional felts or the flood coat and aggregate surfacing are delayed.
Granule: A small aggregate, naturally or synthetically colored, used to surface cap sheets, shingles, and other granule-surfaced roof coverings.
Gravel: Aggregate consisting of rock fragments or pebbles.
Grout: A thin mortar used to fill cracks in masonry and tile.
Grout (Non-Shrink): A cementitious material used to partially fill penetration pockets (pitch pans). A pourable sealer is used afterward.

H

Hypalon: The trademark name for Chlorosulfonated Polyethylene (CSPE), which is a single-ply roofing material.

I

Insect Screen: Material used to inhibit an insects ability to enter a building through openings in a roof such as vents.
Insulation: Material used to help maintain a certain temperature in a building by reducing the flow of heat to and from that building. See also Thermal Insulation.
Interlocking Shingles: Shingles that lock together to provide wind resistance. See also T-Lock.
Inverted Roof Membrane Assembly (IRMA®): A variation of the "Protected Membrane Roof Assembly" in which Styrofoam® brand insulation is used. IRMA® and Styrofoam® are registered trademarks of the Dow Chemical Company.
Isocyanate: A highly reactive organic chemical containing one or more Isocyanate groups. A basic component in Sprayed Polyurethane Foam systems and some polyurethane coating systems.

J

Joint Tape: Tape used to seal joints between insulation boards.

L

Laminated Shingles: See Dimensional Shingles or Architectural Shingles.
Lap Cement: Asphalt-based roof cement used to adhere overlapping plies of asphalt roll roofing.
Lead: Metal used for flashing material.
Loose-Laid Roof Membranes: Roofing material attached only at the perimeter and at penetrations and held in place by ballast, pavers, or other materials.

M

Mastic: See Asphalt Roof Cement.
Mat: A thin layer of woven, non-woven, or knitted fiber used to reinforce a material.
Material Safety Data Sheets (MSDS): Written descriptions of the chemicals in a product provided by the product's manufacturer. MSDS also contain other information such as emergency procedures and safe handling.
Mechanical Fasteners: Devices such as screws, plates, battens, nails, or other materials that are used to secure roofing materials.
Mineral Fiber: Inorganic fibers of glass or rock.
Mineral Granules: See Granules.
Mineral-Surfaced Roofing: Roofing materials with a top surface consisting of mineral granules.
Modified Bitumen: a bitumen modified by one or more polymers such as Atactic Polypropylene (APP), styrene butadiene styrene (SBS).
Moisture Relief Vent: A vent installed through the roofing membrane to relieve moisture vapor pressure that has been trapped within the roofing system.

N

Neoprene: A synthetic rubber produced by polymerization of Chloroprene for use in liquid-applied and sheet-applied elastomeric roofing.
Ninety-Pound: Granule-surfaced or fiber glass or organic felt roll roofing that has a mass of approximately 90 pounds per 100 square feet.
No-Cutout Shingle: A shingle made of one solid strip of material.
Non-Flammable: Material with no measurable flash point.
Non-Friable: Refers to a material's inability to be crushed or pulverized into a powder.
Non-Volatile Content: The portion of a material that will not evaporate.
Non-Vulcanized Material: A material that retains its thermoplastic properties throughout its service life.
Nonwoven: Random arrangement of the reinforcement fibers of a scrim sheet or mat.

O

Off-Ratio Foam: SPF where the 1 to 1 ratio of the A and B components has been compromised and which results in a lower quality material.
Open Time: The time after an adhesive has been applied and permitted to cure when the two surfaces can be bonded.
Organic: Formed from hydrocarbons.
Organic Felt: An asphalt roofing base material manufactured from cellulose fibers.
Organic Shingle: An asphalt shingle reinforced with organic material manufactured from cellulose fibers.
Overlay: See Re-Cover.

P

Pan: The concave piece of "Pan and Cover" tile whose rounded surface touches the top side of the roof substrate.
Pass: The term used to describe the application of one layer of Spray Polyurethane Foam (SPF). The speed of a pass will determine foam thickness.
Pass Line: The distinct line formed between two passes of SPF. This line is the top skin of the bottom pass of the SPF.
Percent Elongation: The maximum amount that a material can be lengthened or stretched before breaking; expressed as a percentage of the original length of material tested.
Perlite: A natural volcanic glass having distinctive concentric cracks and a relatively high water content.. Perlite in a fluffy heat expanded form is used in lightweight insulating concrete, fire-resistant rigid insulation board (R = 2.78 per inch) and potting soil.
Plastic Cement: A term used to describe Type I asphalt roof cement. Plastic cement should not be used on vertical surfaces. See also Asphalt Roof Cement and Flashing Cement.
Plastic Film: A flexible sheet made by the extrusion of thermoplastic resins.
Plasticizers: Material incorporated into rubber and plastic in order to increase their flexibility and workability.
Polyester: Any of numerous synthetic polymers produced chiefly by reaction of dibasic acids with Dihydric alcohols and used primarily as light, strong, weather-resistant resins. In roofing, polyester is used to reinforce fabrics.
Polymer: Any of numerous natural and synthetic compounds of usually high molecular weight consisting of up to millions of repeated linked units, each a relatively light and simple molecule.
Polymer Modified Bitumen: See Modified Bitumen.
Polymeric Methylene Diphenyl Diisocyanate (PMDI): The "A" component in SPF; when mixed with "B", it forms polyurethane. PMDI is an organic chemical compound having two reactive Isocyanate (-N=C=O) groups.
Polymerization: The combining of monomers to produce polymers.
Polypropylene: Any of various thermoplastic resins that are polymers of propylene. They are hard and tough, and are used to make molded articles and fibers.
Polyvinyl Chloride (PVC): A thermoplastic polymer that can be compounded into flexible and rigid forms through the use of plasticizers, stabilizers, fillers, and other modifiers; rigid forms are used in pipes; flexible forms are used in the manufacture of sheeting and roof membrane materials.
Pop Rivet: A small metal pin having a head on one end, inserted through aligned holes in pieces of light gauge metal to be joined and then the head is expanded to join the metal.
Pourable Sealer: A type of sealant that is initially in liquid form commonly used in conjunction with pitch pans to form a water-tight barrier around penetrations that are difficult to flash.
Primer: A material that is applied to a surface in order to increase that surface's ability to adhere to or work in conjunction with a subsequently applied material.
Protected Membrane Roof (PMR): A roof assembly in which the insulation and ballast are placed on top of the membrane component. Commonly referred to as an "inverted roof assembly."

R

Resin: The "B" component in SPF that is mixed with the "A" component in order to form polyurethane. Resin contains a catalyst, fire retardants, a blowing agent, Polyol, and a surface active agent.
Roof Cement: See Asphalt Roof Cement and Coal Tar Roof Cement.
Rosin: Non-asphaltic material used as slip sheets and sheathing paper in roof systems. Also referred to Rosin Paper and Rosin-Sized Sheathing Paper.

S

Saturated Felt: Felt that has been saturated with bitumen.
Screen or Screen Wall: See Equipment Screen.
Sealant: Generic term for a multitude of materials used to seal joints or junctures against moisture or weather.
Sealer: Coating designed to prevent bleedout or bleed-through.
Self-Adhering Membrane: A type of membrane whose bottom surface will stick or adhere to a substrate without the use of an additional adhesive material.
Self-Drilling Screw: A screw with a small drill-bit like tip that will drill its own hole and eliminate the need to pre-drill a hole.
Self-Sealing Shingle: Asphalt shingles with adhesive strips that will soften and stick to the following course of shingles when heated by the sun; used to help against wind uplift.
Self-Tapping Screws: Fasteners that make screw thread receivers when screwed into a hole.
Self-Vulcanizing Membrane: Membrane that is initially thermoplastic in nature but that cures after installation.
Shingle: (1) A single piece of prepared roofing material, either asphalt or wood, for use in steep slope roof systems. (2) To install a wood or asphalt shingle roof system.
Single-Ply Membranes: Roofing membranes that are applied in one layer. Thermoplastic and thermoset membranes are usually Single-Ply Membranes. Single-Ply membranes come in five basic types: (1) Ballasted, (2) Fully-Adhered, (3) Mechanically-Fastened, (4) Partially-Adhered, and (5) Self-Adhered. Seams of Single-Ply Membranes can be heat welded, solvent welded, and adhered using seam tape or other adhesives.
Single-Ply Roofing: Roofing systems where the principal component consists of a single-ply membrane.
Slate: A fine-grained metamorphic rock that splits into thin, smooth-surfaced layers used in steep slope roofing applications.
Slip Sheet: Sheeting material placed between roofing components to prevent those components from adhering to one another or to prevent material damage due to component incompatibility. Slip Sheets may be polyethylene, rosin-sized sheathing paper, or other material.
Solder: Any of various fusible alloys, usually tin and lead, used to join metallic parts.
Solvent: (1) A liquid capable of dissolving other substances such as bitumen. (2) A liquid that is part of a substance and is used to make that substance easier to work with. Once applied, the solvent evaporates and leaves the working characteristics of the substance. Examples are solvent-based adhesives and solvent-based mastics.
Special Steep Asphalt: A roofing asphalt conforming to the requirements of ASTM Specification D 312, Type IV. This asphalt can be used on roofs with slopes up to 6 in 12 (50%).
Splice Plate: A metal plate placed beneath the joint between two pieces of metal.
Splice Tape: A self-adhering (usually double-sided) tape used for splicing membrane materials.
Sprayed Polyurethane Foam (SPF): A monolithic sprayed-on roofing material with a high R-value; formed when isocyanate ("A" component) and resin ("B" component) are mixed at a 1:1 ratio.
Stainless Steel: A highly corrosion resistant steel alloy containing either chromium, nickel, or copper.
Steep Asphalt: A roofing asphalt conforming to the requirements of ASTM Specification D 312, Type III. This asphalt can be used on roofs with slopes up to 3 in 12 (25%).
Steep-Slope Roofing Materials: Roofing materials that depend on their water-shedding capabilities to keep moisture from entering a building. These materials are generally installed on roofs with slopes that equal or exceed 3" in 12" (25%).
Straw Nail: Long-shanked nails used to fasten tile along hips and ridges.
Strip Shingles: Asphalt shingles that are manufactured in strips.
Styrene: A colorless oily liquid, C6H5CH:CH2, the monomer for polystyrene.
Styrene Butadiene Styrene (SBS): The modifying agent used in SBS modified asphalt roofing materials that gives the material a rubber like quality.
Surfactant: Short for "surface active agent." A soluble compound that reduces the surface tension of liquids, or reduces interfacial tension between two liquids or a liquid and a solid having cationic (positive charge), anionic (negative charge), or non-ionic (no charge) nature. The ingredient in SPF that controls the cell size.

T

Tape: See Joint Tape and Splice Tape.
Tar (ASTM DEFINITION): A brown or black bituminous material, liquid or semi-solid in consistency, in which the predominating constituents are bitumens obtained as condensates in the processing of coal, petroleum, oil-shale, wood, or other organic materials.
Terne: Sheet iron or steel plated with an alloy of three or four parts of lead to one part of tin, used as a roofing material.
Terra Cotta: A semifired ceramic clay used in building construction.
Thermoplastic: noun; A thermoplastic resin, such as polystyrene or polyethylene.
Thermoset: A material that cannot be reshaped or formed by heating. EPDM and Butyl are thermosets.
Thinners: Liquids that are used to reduce a material's viscosity when mixed but that evaporates during cure.
Thixotropy: Property of certain materials which liquefy when they are subjected to vibratory forces such as simple stirring or shaking and then solidify when left standing.
Toggle Bolt: A bolt with a separate toggle end that can be flattened to fit through a pre-drilled hole and that springs outward to provide securement when the bolt is tightened.
Tongue and Groove: Premanufactured materials with a convex "tongue" on one side and a concave "groove" on the other so that pieces of material can be joined together by placing the tongue of one piece into the groove of an adjacent piece so that the pieces fit more securely together.

U

Upside Down Roof: See Protected Membrane Roof.

V

Veneer: Any of the thin layers of wood glued together to make plywood.
Vermiculite: One off a group of micaceous hydrated silicate minerals related to the chlorites and used in lightweight insulating concrete.

W

Wind Clip: A clip that slips over the ends of tile, slate and other steep slope roofing materials in order to help prevent wind uplift damage.

Z

Zinc: A bluish-white, lustrous metallic element that is brittle at room temperature but malleable with heating. It is used to form a wide variety of alloys including brass, bronze, various solders, and nickel silver, in galvanizing iron and other metals, for electric fuses, anodes, and meter cases, and in roofing, gutters, flashings, edge metals and also for various household objects. Atomic number 30; atomic weight 65.37; melting point 419.4 &def;C; boiling point 907 °C; specific gravity 7.133 (25 °C); valence 2.