Primer 450 is a two-component primer used to increase the adhesion of urethane elastomers to other elastomeric compounds or as a tie coat to some metal surfaces. Primer 450 cures at ambient temperatures and provides a strong bond that in many cases exceeds the strength of the elastomer. This primer may be applied by spraying, brushing or dipping. In service at ambient temperatures, it is resistant to fresh and salt water, many chemicals and other environmental conditions.

Primer 450 is a two-component urethane primer used to increase the adhesion of urethanes to painted metal surfaces, wood, (some plastic surfaces) or concrete. Primer 450 is required when installing our Speedliner 1000 spray on truck bed liner product into the cargo bed area of light-duty trucks or other painted metal surfaces.  Primer 450 is also used as a bonding agent between new and old urethane coatings. It is applied by spraying, brushing or roller application. For best results, the surface should be cleaned, abraded and wiped with a solvent prior to Primer 450 application. When recoating spray-on truck bed liners, Primer 450 must be used to bond new truck bed liner coating over existing spray-on truck bed liners. Cure time depends on temperature and relative humidity, Mix ratio 1:1 by volume, brush, roller or spray-on application.  See Speedliner product page for complete information on our spray-on truck bed liner products. Primer 450 contains VOC solvents and is classified as flammable material, see material safety information.

Application and Mix Ratio

Both primer components should be at room temperature before mixing. Primer 450 is a two-component material and equal amounts by volume of component A and component B must be mixed together until well blended. Once mixed, the primer will remain usable for two hours.

Standard techniques used in airless paint spray work well with Primer 450. A proper size spray tip should be adjusted to obtain an even spray pattern at the lowest pressure. The primer should be applied in a thin wet coat beginning at the bottom of the item being primed. Runs should be avoided and excess primer should be wiped or brushed from the surface. Poor adhesion of the urethane elastomers to the metal will occur if the primer is applied too heavy. When applying the primer to an elastomeric substrate that has been roughened, the primer should be scrubbed into the surface with a stiff brush in order to achieve intimate contact with the elastomer. An electric drill and wire brush can also be used to prepare the old elastomer surface to a "suede appearance".

Substrates must be properly prepared before primer is applied. For elastomeric substrates, loose elastomer must be cut away and all traces of oil, grease or dirt must be removed with a detergent or solvent. The surface must then be buffed with a wire wheel or very coarse sandpaper to produce a "suede-like" texture. Buffing too quickly or with too much pressure will produce heat and produce an unacceptable sticky surface. All edges or joints should be tapered or "feathered". When Primer 450 is used as a tie coat between urethane top coats the first coat of primer should dry 30 minutes before top coat or other urethanes and urethane base coats are applied.

Coverage obtained with Primer 450 will depend on the porosity or roughness of the substrate being primed. Typical coverage will range from 100 to 400 square feet per gallon. The dry film thickness when priming smooth substrates should be approximately one mil per coat. Overspray and waste must be taken into account when estimating the quantity of material required or a particular job.

Primer 450 dries to a slightly tacky film in approximately 30 minutes at room temperature at which time urethane elastomers may be applied. If Primer 450 is to be cast and heat cured, the primer should be allowed to dry for one hour to allow all solvents to evaporate.

Primer 450 may be applied with a brush or with standard airless spray equipment having a minimum air fluid pressure ratio of 15:1. Fluid pressures of 1,500 psi or less will provide a good spray pattern with a .013 to .020 inch orifice spray tip. The spray machine should be equipped with Teflon or nylon hose and a 100-mesh outlet filter. A tip filter may be required for small tips. The spray should be conductive and the spray machine should be grounded to an earth ground when spraying. Note: Equipment must be clean when used to spray primer. Contaminates such as oil or grease in the spray equipment will interfere with the primer bond. Equipment should be flushed with M.E.K. before using equipment to spray primer.


Working Properties

Mix Ratio By Weight

100 parts A/ 92 part B

Mix Ratio By Volume

100 parts A/ 100 parts B

Viscosity @ 72°F (A Side)

49 CPS

Viscosity @ 72°F (B Side)


Viscosity @ 72°F (Mixed)

30 CPS



Clear Amber

Working Life @ 72°F

2 hours

Cure Time* @72°F

24 hours

*Cure time depends on temperature and relative humidity.


Physical Properties

Specific Gravity (Part A)


Specific Gravity (Part B)


Specific Gravity (Mixed)


Weight/Gallon Part A

8.02 lbs.

Weight/Gallon Part B

7.41 lbs.

Weight/Gallon Mixed

7.74 lbs.

VOC Content per mixed liter

335 grams


Clean Up

Dispose of all empty Primer 450 component containers in accordance with local, state and federal regulations. Empty component containers can be rendered non-hazardous by rinsing the containers with a small amount of mixed material and allowing the solvents to evaporate. The containers will then contain non-hazardous cured urethane.

Storage and Shelf Life

Primer 450 components are shipped from the factory in sealed containers that are purged with dry nitrogen. The containers should be kept tightly sealed and stored in a cool and dry area that is protected from direct sunlight and moisture. Storage temperatures should not exceed 80°F. The shelf life of factory sealed containers stored under these conditions is one year. Containers that have been opened should be resealed immediately after the material has been removed in order to prevent moisture contamination and solvent evaporation. Resin component containers should be purged with dry nitrogen if the contents are not used within 24 hours after opening.


Shipping Class: Class 92.5 Hazardous