Milky Oil Stain Under CV

A finish schedule of sealer, oil stain, conversion varnish leads to trouble on a custom job. March 28, 2012

We were forced into using an oil stain (Old Masters) on some furniture to match some existing product. We are using a vinyl sealer and then conversion varnish over that. On our first small piece (completed nine days ago) we are noticing some white, milky looking effect going on under the cv. Did we not let the stain dry long enough? It was also very humid the day we put our finishes on. Also, my finisher seems to think that it's ok to put on stain and then a light coat of sealer, sand, and then more stain to darken it. Does anyone else do this or are we asking for trouble?

Forum Responses
(Finishing Forum)
From contributor O:
The reason your finish is turning white is because the wiping stain is not dry. As for putting this stain on top of a sealer coat to make darker is also contributing to the milkyness. I would not recommend doing this. Why not thin the stain with lacquer thinner and spray the stain over the wiping stain that was applied by hand on top of the wood to make it darker? Then let the product dry overnight before sealing. This should take care of it.

From contributor E:
If you sealed it then it should be stained again. Will your stain bond to the sealer? I think you may have some bonding issues.

From contributor O:
Contributor E - you are exactly right about inner coat adhesion being a problem when you add wiping stain over sealer. A separation of the top coat from the sealer will cause milkyness, but without visually looking at the piece the problem is occurring either under or over the sealer and is attributed to the stain being wet. A CV finish is different than a lacquer finish from an inner coat adhesion standpoint. Lacquers can bond chemically where the CV needs a certain amount of roughness to adhere.

From contributor F:
I agree with Contributor O. The oil stain is not dry enough. It needs to dry overnight with air movement (small fan). If you stain, seal, sand, and then apply more stain over the sanded sealer you are asking for trouble. If you do this just make sure the stain is dry (again overnight) before putting on another coat of sealer. Then do a tape test to check adhesion before you move ahead to a top coat.

From the original questioner:
We have mixed our own Mohawk pigment wiping stain formula to match the oil stain color. We should have done this in the first place I guess but just like every other job out there, we have a very picky client and this is the stain that was used elsewhere on the project. Ifigured the dead nuts color match was the sure bet and didn't take in to consideration the draw backs of oil stain. If we had the luxury of time it would be a snap but we don't and quite frankly, who does?

From contributor T:
I learned a terrible lesson doing exactly what you are doing, even though I let the stain dry completely and didn't have any milkyness problems. When you spray oil based stain over already sealed wood, the oil dries as a film without soaking into the wood.Your CV will never stick to this film.

To tone in this circumstance, you have to mix inert pigments or dyes into thinned CV to match your stain and spray this onto the surface. Then you can spray your clear coat just after the toner is touch dry.

You can do as you did using the stain as toner if you sand your sealer well, then spray on the stain, and then wipe off all the excess so no film is left. You are actually using the stain as a glaze in this case. Even so, you are the safest here using lacquer as the clear coat since it will better bond with the sealer below.