Restoring water-stained veneer

[bhendrix]

I bought a pair of 1983 CWL Cornwalls on ebay last week for $375 BIN. The finish on the cabinets was badly damaged by water from potted plants. There were black rings and stains and the lacquer had turned white. The cabinet edges and surfaces, surprisingly, were undamaged.

I removed the factory-applied lacquer with lacquer stripper, a scraper, and lacquer thinner. I was left with badly stained raw walnut with black rings and black streaks. The stains are caused by the reaction of the iron in the tap water with the tannic acid found in higher concentrations in oak, cherry, mahogany, and walnut.

I used a solution of 2 tablespoons of Oxalic acid to one pint of warm water to remove the offending stains. Oxalic acid is unique in that it will remove a certain type of stain formed when iron and moisture come into contact with tannic acid in the wood. A black stain is formed when the wood gets wet with tap water (tap water contains iron as a trace mineral). A wet glass or leaky vase left on these woods will produce a black ring. Oxalic acid will remove this discoloration without affecting the natural color of the wood. I applied the solution with a cheap paint brush and allowed it to dry. After four applications, the stains were completely gone. I neutralized the acid with a solution of two tablespoons baking soda per pint of warm water. I then cleaned the surface with distilled water and allowed it to dry.

To make sure the stains are completely gone (after the wood was dry) I wiped the surface with mineral spirits to simulate an oil finish. No stains!! (If you still have stains, apply more oxalic acid.)

This process will tend to raise the grain of the wood slightly. Careful sanding with a very fine grit sandpaper will smooth and clean the surface.

I chose to refinish the cabinets with oil instead of lacquer. I used Watco Danish oil and the results were spectacular. I now have oiled walnut Cornwalls that will fetch the highest value, and no stains.

[sunburnwilly]

Got any before and after pics. ?

[D-MAN]

Nice post, thanks!

DM

[bhendrix]

Sorry, no pics. My college daughter ran off with me camera.

[PrestonTom]

Bill,

Congratualations on your success story. You raised many interesting issues.

1. frequently white spots can also be the result of alcohol on a wax finish

2. good point about the tannins in oak. They also react to any ammonia that might be in a cleaning solution

3. You had much better success with Oxaic acid then I have had. In my limited experience the solution was either too weak or way too strong. In which case it would do nothing at first and then whammo - too much bleaching.

4. I am also a fan of the Watco danish oil.

Would love to see some pictures.

Good Luck,

-Tom

[bhendrix]

Tom,

I, too, was concerned about too much "bleaching", but the "two tablespoons per pint" formula seems to be mild enough to remove the stain without removing the natural color of the walnut. If the wood came out too light, I was going to use some of the Watco Walnut Danish Oil mixed with the "unflavored" Danish Oil to restore the color, but it wasn't required.

[colterphoto1]

excellent recommendations and well done on the patience with the treatment. This is the kind of post that should be permanently filed away for later reference. I for one do not care for the Klipsch lacquer finish on Heritage speakers. The oiled is much more forgiving and easy to work with.

Congrats on a job well done. Maybe 'after' photos one day???

Michael