Epoxy Primers

Epoxy primer comes in two colors: white or dark green; both have identical properties and ingredients and vary only by color.

Cured epoxy primers are completely solvent resistant and are not wrinkled or lifted by fabric cements or dopes.

White is the easiest color to use under any color paint and is always a better choice for aluminum, steel or composites that will be topcoat painted. Dark green is actually white primer tinted green for those who want to simulate the color of WWII zinc chromate on war birds.

There are three parts to an epoxy primer kit: EP-420 Primer, EP-430 Catalyst, and E-500 Reducer; all are required and cannot be substituted.





Epoxy primer is used to coat steel, aluminum, and composite surfaces before painting. It has superior anti-corrosive properties that exceed one-part zinc chromate primers in all levels of performance. Epoxy primers may be used under enamels, Ranthane polyurethane, and a variety of other topcoat paints. Epoxy primers may be applied directly over old one-part primers like zinc chromate or red iron oxide to provide a solvent-proof barrier coat to protect from fabric cements and dopes.


Each component (Primer, EP-430 Catalyst, and E-500 Reducer) is sold individually or in a kit.

Gallon Kit:

1 gallon Epibond or Rand-O-Plate Epoxy Primer, 2 quarts EP-430 Catalyst, 1 gallon E-500 reducer. Yield: 2 gallons of sprayable primer when mixed.

Quart Kit:

1 quart Epibond or Rand-O-Plate Epoxy Primer, 1 pint EP-430 Catalyst, 1 quart E-500 reducer. Yield: 2 quarts of sprayable primer when mixed.


One gallon of catalyzed, reduced primer will cover approximately 1000 sq. feet one coat.

Mixing and Thinning:

Primer may hard settle in storage. Make sure all compacted material is mixed well with a paddle to get everything off the bottom of the can. Once paddled, agitate on a paint shaker for 5 minutes, minimum.

1. Add exactly two parts Primer to one part EP-430 Catalyst. Stir thoroughly and allow sitting for 30 minutes induction time before application.

2. Add 50% E-500 Epoxy Reducer (two parts catalyzed primer to one part E-500 reducer). Additional thinning may be required in warm weather or with some spray rigs.


Use spray equipment rated for lacquers or enamels. Spray three light coats 20 minutes apart allowing each coat to become tacky before spraying another. Do not flood or apply thick coats as you would automotive filler primers; crawling or cratering will result. Unlike automotive primers, this aerospace primer is put on in light coats and does not dry with a chalky texture. When three coats have been applied, the result will be a slick, hard surface that may be slightly transparent. There is no need to paint over the top of Epoxy Primer when used in internal structural components like 4130 steel tube fuselages or aluminum wings; the primer itself is sufficient to act as an internal coating. Scuff dried and cured epoxy primer with an ultrafine scotchbrite pad and wipe with a cloth slightly damp with C-2210 Paint Cleaning Solvent before applying topcoat paint.

Dry/Cure Time:

Epoxy primer will dry to the touch in 30 to 60 minutes in most conditions. However, it takes a full seven days at 70 degrees to chemically crosslink to full solvent resistance. So in simplest terms, if you rush applying solvent-borne topcoat paints or fabric cement over the top of primer that has not cured for seven days, you risk wrinkling the primer. This is most probable in the hours immediately following primer application. As time passes in the seven-day cross linking period, the primer gets more solvent resistant, and the probability of wrinkling decreases. After seven days, it is impervious to all solvents.

Pot Life:

The sooner applied after induction, the better the service life durability. Maximum pot life is seven hours at 70 degrees. Discard mixed primer when viscosity increases or when primer becomes stringy. Do not add reducer to "save" primer that has become viscous or is beginning to harden.

Clean up:

Use E-500. MEK may be substituted but does not clean tools and spray guns as well as E-500. Do not allow primer to dry in the gun; it will be almost impossible to remove. Clean gun as soon as you finish work.

Shelf Life:

Primer and reducer, 4 years in an unopened container. EP-430 catalyst, two years in an unopened container.



Catalyst for either Epibond White Epoxy Primer or Rand-O-Plate Green Epoxy Primer.


One pint and one quart cans.

Shelf Life:

Two years in an opened container. Avoid storage above 100 degrees F.


See instructions under epoxy primers above.



Used to thin Epibond and Rand-O-Plate primer as well as EV-410 Epoxy Varnish. Follow thinning directions on the primer and varnish cans. Do not substitute other solvents or thinners in these epoxy products.


One quart and one gallon cans.

Shelf Life:

Unlimited in closed containers.



Accelerates the drying time of epoxy primer or varnish in cold weather.


Half pints only.


  • EPOXY PRIMERS: Add one to a maximum of two fluid ounces of accelerator to a quart of catalyzed and thinned epoxy primer Do not exceed 2 fluid ounces per quart.
  • EPOXY VARNISH: Add one to a maximum of three fluid ounces to a quart of catalyzed and thinned varnish. Do not exceed 3 fluid ounces per quart.