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Frequently Asked Questions

What is the lowest temperature that body fillers can be used in?
45° - 50°F (7° - 10°C); if using below 65° F, the amount of hardener used should be slightly increased.
What is the highest temperature that body filler can be used in?
Body filler can sustain temperatures up 180° F (82° C) of constant heat. Temperatures above 180° F (82° C) can cause the filler to soften and lose adhesion.
What is the mixing ratio for body filler to cream hardener?
For a 3-inch diameter circle of filler (approx. 1/2-inch thick), squeeze out a 3-inch ribbon or strip of cream hardener. Or, use a golf ball size amount of filler, sqeeze out a 1 1/4-inch ribbon or strip of cream hardener. Filler should be a pinkish/salmon colour when properly mixed, using red cream hardener.
Does it matter what colour the cream hardener is?
No. The colour of cream hardener will not affect curing or cause staining.
What solvent should be used for cleaning up?
Acetone or lacquer thinner only.
Does paint thinner or mineral spirits work as a clean up solvent or body filler remover?
No.
How can I remove cured filler?
By using a quality automotive paint stripper or by sanding; However, caution should be used when using paint stripper on most surfaces. Do not use paint stripper to clean hands.
Body filler is not curing, why?
Either not enough cream hardener was used in the filler, the cream hardener is old and beyond it’s shelf life or filler is older than 1 to 1-1/2 years. The body filler may have also been applied in extremely cold conditions. If the filler is a grayish colour, the filler hasn’t been mixed.
Filler is curing too fast
Too much hardener was used. Normal gel time is 4-6 minutes at 77° F. The proper mixing ratio for body filler & hardener is 50 to 1 by weight.
When should body filler be sanded?
In 20 to 30 minutes.
How thick should fillers be applied?
1/4-inch per layer for automotive and home applications. Glazes and putties should be applied 1/8 of an inch per layer.
When can body filler be painted?
45-60 minutes after the application for both automotive paint & house paint.
What types of paint should be applied over filler?
All types of automotive paints, including house paints such as Latex and Oil based paints.
What type of primers can be used?
All house and automotive primers. Etching primers should not be used due to their acid content.
What causes my body filler to have pinholes?
Mixing in a circular motion, which forces air into mix or using too much cream hardener, which causes gassing. Mixing should be done in a back and forth wiping or folding motion.
Can body filler be applied to wood?
Yes, body filler is the best type of wood filler because it chemically cross-links to cure. It is cured and sandable in only 20 minutes, and paintable in 45 to 60 minutes. It is also compatible with all house paints and primers. Body filler can be drilled, tapped, routed and carved.
Can filler be used on concrete?
Yes, it can be used to fill holes and cracks in dry concrete.
My can of filler is not filled to the top; it seems a little low, why?
Cans are sold by weight.
Is body filler resistant to gasoline?
Yes, but can only be used to repair the outside surface of metal gas tanks that contain minor pinholes. Filler cannot be submerged in gas.
Is body filler water resistant?
Yes. Water absorption tests show that filler only absorbs 0.3% of water, which is considered minimal. Therefore, body filler is not waterproof by itself but is water resistant.

Note: If the application is primed and painted, the paint will render the application waterproof.
Can I apply filler over a painted surface?
No, all applications should be sanded down to the bare surface including wood and metal, unless using a premium filler.
Can body filler be thinned to make it pourable?
Yes, thin with 4 parts body filler to 1 part polyester resin (Fiberglass Resin, Part 404) or 25%. Use CREAM HARDENER ONLY to catalyze. Working time and cure time/dry time will be lengthened.
Will body filler melt styrofoam?
Yes, but only for the first 3-6 minutes while the filler is in an uncured state; doing very little damage.