Wash coat vs. Conditioner

[Clif Liliedahl]

Can someone provide definitions of these two "undercoatings"?

I need to provide blotching protection on Cherrywood prior to using Minwax Cherrywood Gel Stain #607. Which one will do the best job?:confused:

Many thanks.

[Steve Schoene]

The definitions aren't totally consistent, but basically as I see it, a wash coat is a top coat thinned to make it very thin Like 1 lb. cut shellac or varnish thinned with two parts mineral spirits to each part of varnish.

A conditioner is a top coat thinned to make it very thin, but put into a special package so you can pay a higher price for the thinner and so they can give you misleading directions to apply top coat or stain "within two hours" instead of doing what you should do by letting it fully cure. (I should cite Bob Flexner about this issue.)

Have you tried the gel stain on a sample of the cherry you are using? Gel stain doesn't penetrate very much so is already less prone to blotching.

Finally, do you really need to stain the cherry? Giving it a good sun tan out doors can go a long way to starting its natural color change. The cherry is going to continue to darken so that you may end up darker than you really want after a couple of years.

[Kim Spence]

A Wash Coat typically dries to a film to form a physical barrier that prevents over absorption of the stain in the areas of the wood that are prone to over absorption. Wash Coat can be any type of clear topcoat thinned to your liking - shellac, lacquer, varnish/poly, etc. The more you thin it, the less it fills the pores and the more stain will stick making the finish darker. Technically if you apply stain after applying a washcoat you're glazing and not staining.

A Conditioner doesn't really form a physical barrier, rather you slather the wood with the conditioner until the areas that are prone to overabsorption quit absorbing the conditioner, wipe off the excess, and immediately apply the stain. Because the blotch prone areas are already mostly saturated with the conditioner, excess stain won't be absorbed resulting in a much more even finish overall. A good starting point for a conditioner is a mix of 10% Boiled Linseed Oil and 90% Mineral Spirits (this will require use of oil based stain for compatibility).

[Clif Liliedahl]

Yes, I did try the gel stain on a sample cherry veneer, and got some blotches. I want to try the conditioner next, but the veneer is pretty expensive. So before I do, I'm looking for more info.

What you two guys (Kim and Steve) have provided helps me make a decision.

BTW, are either of you familiar with "vinyl sealer"? I've turned up a few references to it as a pre-stain color balancer or whatever, but am having difficulty locating detailed information.

In any case, thanks to both of you. :)

[glenn bradley]

I use a 2lb cut shellac thinned a further 1:1 (or more) as a wash/sealer. For example; 1 part Zinsser's Seal Coat mixed with 1 part (or more) denatured alcohol. The amount of thinning depends on where you are and what the weather is like.

I SoCal a 1:1 mix is thin enough to just seal against blotching but dries super fast. I apply with a rag and don't go back over. Dries to touch in minutes. Dries to sand in about half an hour; I hit it with a syntho pad to remove nibs and then carry on with the finishing regiment.

[Steve Schoene]

Vinyl sanding sealer is a spray only product for specific applications with catalyzed lacquer and conversion varnish. It, like any of the thinned finishes will provide some stain blotching protection, but it's special properties have to do with adhesion and protective qualities of the top coats, as I understand it.

[Carl Eyman]

On the can it says it's a stain, but it is clear as a bell. It is a water thin water based product that is absorbed readily into the wood on porous portions and pretty much stays on the surface on less porous. It dries very quickly so you can sand off the surface residue with 220 or finer, but the absorbed portion prevents the stain from penetration too deeply. I used it on the carved cabriole legs of chairs I made. When I tried water based dye without using this product the carved part looked black and the long grain was barely colored. Jeff Jewitt recommended it and it worked great. I'm making some cherry end tables now and plan to use it on them.