Sealing Up a Bleeding Finish

Shellac is the go-to barrier coat for evil spirits that soak through topcoats. But don't sand the shellac or you'll defeat its effectiveness. June 18, 2013

I have a customer with an older cabinet converted over to linen cabinet. The problem is it started bleeding an orange color on all the linens and if you wipe your hand across the wood, you get orange fingers. They had someone sand and seal, but it bleeds back through over time. Any thoughts?

Forum Responses
(Finishing Forum)
From contributor L:
Use shellac to seal it. If you are going to be putting another finish coat on it, use dewaxed shellac.

From contributor C:
Most likely an oil soluble synthetic dye was used, notorious for bleeding through solvent base coatings, especially lacquers.

A shellac product will seal in the offending bleeder, but I would first advise you to wipe down the entire cabinet with den-alcohol to remove the surface bleed. Once no more orange is coming off on the rags, the shellac can be applied and be more affective. Again, if you need to apply further coatings over the shellac to adjust sheens, only use Zinsser sealcoat as the shellac.

Don't sand the shellac! If you abrade the surface it will not work and continue to bleed anymore orange out through the surface.

If by chance this is a painted piece or pigmented finish, then use Zinsser shellac based Bin primer instead of the sealcoat. This will give the same barrier/isolation protection, but is better than clear shellac by far.

Note: The reason this is taking place is because the oil soluble dyes rise to the surface of the coating when a liquid solvent coating is applied over them. This is called bleeding, and why you need something to isolate the dye bleed. Shellac is the one thing that will not allow the dye to bleed through the surface and why if you sand it, it will no longer act as a bleed barrier and thwart your efforts.

Also if there is a need to re-coat with solvent clears - apply the first coat or two very lightly, so they do not aggressively soften the shellac finish, which could allow the dye to strike through even the shellac, then proceed with a normal coat of finish.

As always, test the entire process out on a sample first.