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Adhesive Contact Time: The period of time in which an adhesive, such as an epoxy, will remain in its tacky condition after application under specific conditions of temperature and humidity. It is the time available before the adhesive “dries” that something else can stick to it like fresh concrete or a second coating.
 
Binder: A system used to mix with aggregate to create a high strength epoxy mortar.
 
Blush: An oily residue that forms on the surface of epoxies under some conditions.
 
Class: Relates to the ASTM C-881 specification and identifies the surface temperature at time of application. Class A epoxies are intended for use when the temperature is below 40ºF, Class B epoxies for 40ºF to 60ºF and Class C epoxies for over 60ºF. NOTE: A Class C epoxy can work in Class B condition, but should not be used in place of Class A.
 
Comprehensive Strength: The ability of a material to support a load. For example, concrete usually has a compressive strength of 3000-4000 psi.
 
Curing Agent: A liquid chemical formulation that reacts with an epoxy resin to convert it to a solid form. Synonyms are Part B, Reactor or Catalyst.
 
Elongation: The degree in which a product will stretch under tension before it breaks. This degree is expressed in a percentage of its original length. For example, a tensile elongation of 10% means the product stretched 10% more than its original length before breaking.
 
Epoxy Resin: A special liquid chemical formulation capable of converting to a solid form when mixed with a curing agent. Usually referred to as Part A.
 
Exotherm: A chemical reaction which generates heat. This type of reaction occurs when epoxies cure.
 
Final Cure: The time required for an epoxy to reach 100% of its rated physical properties. Usually expressed in hours or days.
 
Flexural Strength: The ability of a material to withstand bending before reaching the breaking point. Usually measured in psi.
 
Gel: An epoxy when in a paste consistency form, can be applied on overhead or vertical applications.
 
Gel Time: The period of time it takes a liquid epoxy formulation to form a gel consistency during the cure process.
 
Grade: Denotes the viscosity of ASTM – formulated epoxies. Grade 1 is low viscosity, Grade 2 is medium viscosity, and Grade 3 describes non-sag grade materials.
 
Hardness: The relative resistance of a material to indentation. In the plastics industry, it is measured on a standard scale known as Shore.
 
High Modulus: High strength material that is rigid. Used specifically where high strength is needed (see “Modulus”).
 
Hydrophobic: Repels water and uses this property to obtain adhesion in wet applications.
 
Hydrophillic: Absorbs water and uses this property to attain adhesion in wet applications where the introduction of moisture into the system and the resulting low modulus will not be dangerous.
 
Impact Resistance: The ability of a material to withstand breaking due to a sharp blow.
 
Impregnation: The process of thoroughly soaking a material such as fiberglass, wood, paper or concrete with a synthetic liquid resin so that the resin is absorbed within the material.
 
Initial Cure: The stage in which liquid epoxy, having become solid, has reached the majority of its ultimate physical properties. Usually expressed in hours or days.
 
Low Modulus: The condition in which a material is slightly flexible. Used where resilience will withstand expansion and contraction, vibration, impact and stress. (see “Modulus”)
 
Modulus: Denotes the value of stress ratio (load divided by area) to the strain (such as elongation) of a material. It is a measure of the relative flexibility and resilience of a material (i.e., rubber has a low modulus and steel a high one). Modulus is expressed in psi.
 
Polymer: A broad class of chemicals such as epoxy, polyester, nylon, acrylics and polyurethanes. Usually made by causing a chemical reaction between two or more basic chemicals called monomers.
 
Pot Life: the time it takes for a formulation to harden once two parts of an epoxy are put together. The time depends on temperature, volume and quantity of the mixture.
 
Primer: A coating applied on a surface to improve the adhesion of an application such as an epoxy system or other coating.
 
Shear Strength: The ability of a material to withstand a stress that makes two contacting parts slide upon each other in opposite directions.
 
Solids: Non evaporating material.
 
Tack: Stickiness of an adhesive.
 
Tensile Strength: The ability of a material to withstand a load under tension (i.e., when being pulled apart). Tensile strength is expressed in psi.
 
Thixotropic: Materials that are gel – like at rest, but fluid when agitated.
 
Type: Describes the basic use to which (ASTM – formulated epoxies are intended (i.e., Type I is an adhesive for old to old surfaces, Type II is for bonding new to old concrete, and Type III are binder/coatings (skid resistance).
 
Viscosity: Measure of the flowability of any liquid system such as curing agents and resin. Expressed in a scale called centipoise (cps). Water has a viscosity of 1; heavy cream is approximately 1,500; karo syrup is approximately 3,000.