Troubleshooting Air Dry Leather Filler Putty

The air-dry putty is peeling.

There are three possible reasons:

1. Sanding where the putty is thinly feathered on the perimeter of the repair.

Air dry putty adheres best to worn, absorbent areas like suede or fabric. Where the putty overlaps finished or undamaged areas, it has less to grab, and care should be taken when sanding these areas.

The Solution: Trim or shave away away any bulky peeled sections. Use rubbing alcohol to melt and thin the peeled edges. Allow to completely dry. Apply more filler, minimally, as needed. Avoid sanding, and use alcohol to smooth imperfections. Do a final texturizing coat to avoid a smooth, patched appearance.

2. The repair area may have residue from other conditioners, furniture polish, or body oil.

These may inhibit the putty's ability to bond to the surface.

The Solution: Clean thoroughly with lacquer thinner. Acetone can also be used with caution. Then re-repair using the suggestions for #1.

3. Filler was applied too thickly or is not fully cured.

Water in the filler evaporates in the curing process. The surface will skim over, giving the illusion that it’s dry. Applying more can then peel up the skimmed surface.

The Solution: Apply thinner layers. Ensure the filler is completely dry before applying more. Use an incandescent bulb or direct sunlight as a heat source to accelerate cure time. Hair dryers are not recommended, because they push moisture inward.

The air-dry putty is still tacky.

This is common and usually remedied with a final thin texturizing coat followed by color.

First, make sure the putty has properly cured. Though technically an air-dry putty, it takes more than just a warm room to cure in a timely fashion. A heat source like an incandescent bulb, heat lamp or sunny window are needed to elevate the surface temperature to a range of 120º - 145º F (49º - 63º C). Hair dryers are not recommended, because they push moisture inward and prevent the water in the putty from evaporating.

Even with a heat source, it may take 20 minutes to a couple hours to cure, depending how thickly putty was applied as well as humidity. For this reason, thin layers are better than thick layers. Ensure the putty is completely cured and returned to room temperature before applying more.

If the putty is not curing, here are possible causes:

1. Residue from conditioner, body oil, or plasticizer is inhibiting the putty from curing.

Leather with oil stains may require extraction. Conditioner residue or a degrading urethane finish may also be the culprit. With vinyl, plasticizers can migrate outward and react with the putty.

The Solution: Make sure to clean the surface with denatured or rubbing alcohol prior to application of filler. Sometimes a more aggressive solvent like lacquer thinner is needed. Acetone can also be used with caution.

2. Adhesives used to subpatch any hole may not be dry and are preventing the filler from doing so.

The Solution: Wipe away uncured filler putty with alcohol. Ensure any glue used to subpatch has completely cured before proceeding. Letting it dry overnight is a good idea.

The putty dried with bubbles.

This is a sure sign of too much heat. The air-dry putty is water-based. If the surface gets over 212º F (100º C) where water boils, the filler will too.

The Solution: Use a needle to poke a tiny hole in each bubble and deflate.

If the bubble lays down smoothly, apply a tiny bead of filler in the hole and smooth with your finger to seal it.

If the bubble does not lay down smoothly, try melting it with a little denatured or rubbing alcohol on a lint-free rag or q-tip. Allow to completely dry. Apply more filler, minimally, as needed. If you're using a heat lamp or incandescent bulb, move it farther from the repair area. Avoid sanding and do a final texturizing coat to avoid a smooth, patched appearance.