Q:
The interior walls of my mountain condominium are covered with tongue-and-groove clear cedar paneling. The paneling, installed about 15 years ago, has darkened with age as cedar usually does. I’d like to return the cedar to its original lighter color. I’ve bleached exterior cedar siding successfully in the past, but that process involves flushing with copious amounts of water. How can I achieve the same results in an indoor environment?
Robert Ledterman, Los Alamitos, CA
A:
Jeff Jewitt, author of Great Wood Finishes, replies: The process that causes wood to change color when exposed to light is called photooxidation, and in some species such as cedar and cherry, it takes place quickly.And it doesn’t take a lot of light to make cedar change color.
The process for reversing this color change involves the application of a bleaching agent. One such agent, sodium hypochlorite, which is the active ingredient in Clorox (about 5%), works well, as does commercially available wood bleach. Of the two, I think Clorox is the better, safer way to go, assuming it leaves the cedar with a satisfactory color. Start with a 50:50 solution of Clorox to water. I’d try the bleach solution on a test piece or in an inconspicuous area to be sure it works all right.
As long as there is no finish on the cedar (there shouldn’t be if your test pieces lighten up), I’d put drop cloths down and just sponge the bleach onto the paneling (it’ll work a little faster if you warm the solution). You can also use a plant mister to spray the solution onto the paneling.
Increase the bleach-to-water concentration if necessary to achieve the desired color. After you reach the color you want, use vinegar and water to wash down and neutralize the bleach. One part white vinegar to 3 or 4 parts water is fine. Dip a sponge in the vinegar solution, and wipe it on the bleached wood. Rinse the sponge in clear water before dipping it again in the neutralizing solution. Once the cedar is dry, you can leave it as is or apply the finish of your choice. But if you want to lighten it again in the future, I’d leave the cedar natural.
