How To Repair Damaged Wood Finish
Nosotros may receive a committee when you lot use our affiliate links. However, this does not impact our recommendations.
Work miracles on wood with oxalic acid.
Watering a potted found tin be disastrous if the constitute lives on elevation of something fabricated out of wood. We've all seen the white spots and black rings that can upshot when h2o seeps through the pot. And if you've e'er tried to sand out these marks, you know it'south a tough job that tin can leave telltale depressions on the surface. Fortunately, in many cases, this type of damage can be well-nigh magically undone by treating the woods's surface with oxalic acid.
Oxalic acid removes the gray color from oxidized wood, without changing the wood'due south natural color. That'south why it's commonly used as the agile ingredient in deck cleaners, and why restorers utilise it to remove greyness or black water stains on furniture (see "Oxalic Acid Undoes Rust," beneath). Oxalic acid is also used in some household cleaning products for removing hard water stains, and information technology has many industrial uses as well. Although it is found as a natural ingredient in some vegetables (spinach and rhubarb), oxalic acid is quite toxic if ingested in concentrated form.
Identify the stains
Every stop repair job is unique, of grade, so the outset step is to thoroughly examine the problem. The chest chapeau shown here has both whitish marks (likewise chosen blushing or bloom), and dark gray and black discolorations. White marks are usually in the finish; night discolorations from water bespeak more significant damage, considering they're down in the wood.
To help formulate a plan to repair this finish, I dampened the entire chapeau with mineral spirits [Amazon] (paint thinner). This testing method is useful anytime yous want to look closely at either old dry finish or bare wood. The expect of the paint thinner-dampened surface is similar to how it would await if shellac or a articulate oil based finish were applied. In this case, dampening the surface makes the whitish marks temporarily disappear (they reappear when the mineral spirits evaporates). That means a glaze or 2 of finish is all that's needed to take care of the white marks. (This is a stroke of luck; if the white marks hadn't disappeared, additional repair steps would be necessary to remove them, and that's a topic for another story.)
Now I can focus on the black rings. The mineral spirits test shows that they get darker, and that makes them skillful candidates for treatment with oxalic acid. If the oxalic acid works, I won't have to aggressively sand the unabridged chapeau. Not only would sanding remove the remaining intact stop (80%, in this case), it would too lighten the lid's aged cherry color, so information technology would no longer match the rest of the chest that it belongs to.
Care for the stains
1. Starting time past thoroughly cleaning the surface. First, wipe information technology downwards with mineral spirits, to remove smooth and other crud that's greasy or waxy. Mineral spirits besides shows what the damaged areas volition look like with a clear finish applied.
Every step of this treatment should be done consistently to the unabridged surface, not only the damaged area. The procedure involves flooding the surface with h2o. Fortunately, the harm shown here is on solid wood—using this treatment on a veneered surface tin exist risky.
ii. When the mineral spirits has evaporated, complete the cleaning process by wiping the surface with soap and water, using a soft material, to remove h2o-soluble remainder. Permit the surface to dry completely.
The first footstep is a thorough cleaning, using two different cleaners. Mineral spirits removes greasy balance, such as quondam wax or polish (Photo 1). Mild dish soap and h2o removes whatsoever water-soluble crud (Photo 2). Neither of these processes will damage an intact finish.
iii. Sand lightly, using fine paper, a soft block and very lilliputian force per unit area. Although the goal is to remove the raised grain from the damaged area, information technology's important to sand the entire surface to maintain consistency.
The grain is raised very slightly in the water-damaged surface area, and so a little sanding with 400 grit paper is necessary (Photo iii). This pace should have about one minute.
4. Mix a saturated solution of oxalic acid in a non-metal container. Add a spoonful at a fourth dimension to the water and stir, until a layer of not-dissolved oxalic acid remains at the bottom.
Mix up a saturated solution of oxalic acid [Amazon] by adding the crystals to a jar of warm water with a plastic spoon (Photograph 4). Do not apply any metallic containers or utensils—the acid could react with the metal. Add together crystals a spoonful at a time and stir until no more than will deliquesce into the h2o. I always use a saturated solution, so that I have a maximum-forcefulness problem solver.
5. Wipe on the oxalic acid solution. Get out it on the surface for about five minutes to achieve the maximum effect. Then wipe off the excess and let the surface dry thoroughly. The effect can be almost instantaneous.
Wearing gloves and eye protection, use a rag or sponge to saturate the entire surface existence treated, not just the dark spots (Photo 5). Keep the surface wet for about five minutes to let for the maximum issue. Then wipe off the excess and let the surface dry completely. You may see the outcome immediately equally you apply the acrid, or the spots may disappear gradually, equally the acid dries. If a second application of acid is necessary, expect to apply it until the outset application has thoroughly stale, or it won't piece of work. If two or iii applications exercise not remove the stain completely, more acid is not likely to help. You'll have to alive with the remaining discoloration or resort to sanding to remove it. However, practise not sand until you have thoroughly rinsed the surface—breathing dust that contains oxalic acrid is extremely unpleasant and potentially hazardous.
6. Inundation the surface with water repeatedly, to remove whatsoever remaining oxalic acid crystals.
When yous've completed the oxalic applications, it's imperative to thoroughly rinse the treated surface with lots of make clean water, to flush away any acid that remains on the wood (Photo vi). Alluvion the surface several times and dry it with a make clean cloth or paper towel each time. Allow the surface dry betwixt each flooding.
Attempting to "neutralize" the acid that remains on the surface with a mild alkali such as baking soda, borax or ammonia is a cleansing option that is frequently mentioned as an culling to rinsing. However, I have never seen any accurate formulas that would make this chemic balancing act a applied possibility. Besides, I know that thorough rinsing works.
Dampen the sur- face with mineral spirits to test the results. Here, the whitish chroma areas virtually disappear and the blackness marks are 99.9% gone. The repair is consummate; it's time to rebuild the end.
After the lid has thoroughly dried, don a respirator and lightly sand the unabridged surface with 400 grit paper, to cut dorsum any grain raised by the oxalic treatments. Exam the surface again with mineral spirits, to gauge the results (Photograph 7). The test on this lid indicates that the surface is gear up for finishing (Photo 8).
In this instance, the cease is blonde shellac, the same finish as the original. Calculation a waterproof end over the shellac could help to forestall future damage. Moving the plant may be a better option.
Product Recommendations
Here are some supplies and tools nosotros observe essential in our everyday piece of work around the shop. Nosotros may receive a commission from sales referred by our links; yet, we take carefully selected these products for their usefulness and quality.
-
Flush Trim Flake
-
Handscrew Clamp
-
Titebond Hide Gum
Recommended Posts
Source: https://www.popularwoodworking.com/finishing/repair-water-damaged-wood/
0 Response to "How To Repair Damaged Wood Finish"
Post a Comment