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| Leave it to the pro. Michael Dresdner, a nationally known wood finishing and woodworking expert, has answered hundreds of common wood finishing questions in Varathane’s Q&A library to help you successfully complete your project. Click on a link to the left for help and solid advice. |
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| "We have some knotty pine in the kitchen, and would like to refinish it. I what to get as much orange out of the wood as possible. How many times can I bleach the wood?"
You can bleach it as many times as you like. However, different bleaches do different things, and choosing the right one will save you time. Of the four common wood bleaches, two may help you, and two others will not.
First, try flooding full strength household laundry bleach (Clorox, etc.) onto the clean, sanded wood, and let it dry overnight. Chlorine bleach removes dyes, commonly used to color wood, though not pigments. Make sure the bleach is fresh, since once opened, it starts to lose efficacy.
If the orange color is the wood itself, aged from sun exposure, you can get back to white wood with two part wood bleach, sometimes called A/B bleach. It will come in a box containing two bottles, marked A and B. You mix the two and immediately apply the mixture to the wood. This bleach is very caustic, so work carefully using synthetic applicators or brushes, and wearing gloves and goggles. Again, let it dry overnight, then wash the surface with clean water to remove any bleach residue.
Unfortunately, none of the bleaches will remove all pigment stains. While A/B bleach may remove some pigment stains, others are beyond its reach, and can only be removed by sanding. Incidentally, you can also mitigate the orange by choosing a complimentary color for your stain. A light blue-gray stain, such as driftwood, or a darker purple brown, such as cabernet, will minimize the orange, just in case you can’t get it out with bleach. |  | |
| "After stripping walnut veneer several times, there is paint still imbedded in the grain. How do I remove it? There must be something that will remove it."
In this case, the "something" is elbow grease, coupled with paint remover, but when is just as important as how.
When you approach a stripping job, make sure you have the time to go all the way down to the bare wood in one shot. That means it is wiser to work one section until it is completely clean than it is to remove the first layer or two of finish from the whole piece. Once you wet the finish with stripper, you must keep it wet until all the paint is off. Letting the wood dry after stripper has been on makes it even harder to get the residue off later. At times, that means draping or bagging the wet piece with plastic sheeting or bags to keep the stripper from evaporating, or it may mean re-applying stripper immediately after scraping the majority of the gunk off the surface.
At this point, you must apply the strongest stripper you can find, and keep the remaining finish wet with stripper until it is softened all the way down into the pores. Before it dries, scrub the softened paint out of the pores with whatever is appropriate, which may include stiff scrub brushes, old toothbrushes, sharpened dowels, coarse string, and nylon abrasive scrubbers. Add more fresh stripper as you work with the scrub brush. When everything is moving out of the pores and onto the surrounding wood, then it is time to wipe up the gunk. Scrubbing with lacquer thinner often helps float the gunk to make it easier to wipe up, but save that step until you are sure all the finish has been softened, even in the pores. | | |
| "I have some unfinished poplar rocking chairs. They have been out on the porch and have gotten kind of dark in the grain. I would like to put a good finish on them, but how do I get the wood clean?"
You’ll need to both bleach them and sand them, and I will explain why.
Unfinished wood does two things; the surface typically changes color, but it also oxidizes. You may not see the oxidation of the surface, but it has the effect of preventing finish from adhering to the wood. Hence, putting a finish on wood that has had a chance to age unfinished means you run a high risk of it peeling or delaminating later.
First, clean the chairs by scrubbing with TSP and a nylon abrasive pad. Then, treat them with a wash of oxalic acid. You’ll find it, sometimes labeled as "wood bleach," in the hardware or home store. It is a white, crystalline powder that dissolves instantly in warm water. Make about a 10% solution, and flood it onto the wood. It should remove any gray discoloration and bring the poplar back to its original color. Let the oxalic acid dry overnight, then wash off the residue with clean water, or vacuum the dust off, and sand the surface once it is dry. Be careful; in its dry form, oxalic acid is irritating to mucous membranes and is considered toxic, so wear a dust mask while sanding.
After you go through this ritual, you will be ready to stain the chairs and coat them with an exterior spar urethane. You’ll also resolve that, in the future, you will coat pieces you intend to finish before you put them outside to weather. | | |
| "We have some pine furniture that was painted antique green. We tried to strip it to refinish it, but can’t get it clean. How do we get that paint out of the wood grain?"
It’s not easy, and in some cases, it is almost impossible.
Paint on raw wood gives the wood pores a chance to soak up pigment. Stripping the paint off with liquid strippers, which dissolve the old paint, can often drive the pigments further into the spongy wood. Very porous woods, like pine, can sometimes absorb pigment deeply enough that even diligent scrubbing leaves a shadow of color. At times, the only way to get the color completely out is to sand the wood, and that may mean a good bit of sanding. |
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