Evening the color of white oak

Creating a natural-looking, uniform finish for white oak. January 3, 2001

We are preparing a set of samples for a large area of rift white oak. This project includes solids and veneers.

The owner wants a light color--he prefers the color of unfinished white oak. We have bleached first, to create a light background from which to add color to achieve a "natural" finish. Some darker white oak boards turn from nicotine beige at the first application of bleach, to urine yellow as more bleach is applied. Any nifty chemical solutions to counter-act this?

The client and architect have both specified a minimum build, low maintenance finish. We use a two-part polyurethane from Ilva. Ilva is non-yellowing, very scratch, water, chemical and wear resistant, has excellent clarity and is fast build.

Unfortunately, the build properties don't allow us to tone without adding significantly to finish film thickness. In the opened grain of oak, this starts to look very "plastic”. Ideally we would apply a seal coat, as thin as possible, following this with an equally thin top coat. We want to avoid staining as this will result in coloring in the open grain.

Forum Responses
If you want to even out the color of the white oak and make the light and dark areas blend more, consider a "sap" stain. Apply it to the lighter staves and mouldings to make them blend better with the darker. This obviously won't make them lighter--just more consistent. A sap stain is made fairly easily and some manufactures even offer one for use with their system.

If you want to make your own, here is a starting point. Use a solvent of choice (I like acetone), add a little binder, about 5-10%, vinyl sealer works for me, then add pigments to get the desired color. This will typically be a combination of raw umber, red, yellow, and brown.

White oak is the problem here. Would the contractor go with another wood? Ash, maybe? Ash bleaches much more evenly, no dark grains like white oak. After bleaching ash, tone in color desired with a methanol dye mixture. Or if just white oak, bleach only the dark grain and tone to match. Ilva's urethane is fine to use over methanol dyes.

The product you use is very good. You can tone with it--just thin it way down. Do the thinning after you catalyze it. When adding colorants, I like to pre-reduce them with reducer 10:1 first, then add them to your catalyzed and reduced PU. I have thinned it down 200% to shade with and had no problems. If you tint both seal coat and topcoat maybe you could pull it off, but color control would be in the hands of the sprayers.

Bob Niemeyer, forum technical advisor