The Woodworker’s Guide to Bleaches

Everyone knows that bleach whitens laundry and disinfects surfaces, among other household uses. But not everyone is aware that bleach is a useful tool for woodworkers as well.

With bleach you can achieve a specialized finish on your favorite wood surface, such as pickled flooring or antiqued tables and cabinetry. Bleach allows you to remove the ink smeared across your woodwork or lighten the stains on the floor. Bleach works wonders in a variety of situations. You just have to know which one to use.

Types of Wood Bleach

The same bleach you add to your washer isn’t the only type of bleach used on wood. All bleaches create a chemical reaction that removes color. With this in mind, there are three types of bleach that qualify for use on wood:
Chlorine Bleach: No matter which brand you choose, chlorine bleach – the mildest form of wood bleach — works wonders in some situations.

Chlorine Bleach: No matter which brand you choose, chlorine bleach – the mildest form of wood bleach — works wonders in some situations.
– Attack dye stains.
– Treat organic stains such as blood, berry-based substances, tea, and food.
– May require more than one application, depending on the stain severity and other conditions.
– Choose between liquid laundry bleach (available in any supermarket) or swimming pool chlorine (available in the pool section of your favorite big box store or pool supply under the name calcium hypochlorite). Calcium hypochlorite is much stronger than liquid chlorine bleach.
– Use liquid bleach at full strength. Dissolve swimming pool chlorine in water, adding enough chlorine to the water to create a saturated solution in which no more will dissolve.
– Rinse the wood, after bleaching, with distilled water.
– Neutralize chlorine bleaches with a mixture of one quart (distilled) water to 2 T. baking soda.

Oxalic Acid: Stronger than chlorine bleach, oxalic acid (available in pharmacies, home improvement centers, and hardware stores) works well in other circumstances.
– Combats rust and iron stains. No other bleach works as well on them.
– Removes water stains. Water stains – usually black spots or patches — are actually a result of the trace of iron in the water interacting with the tannic acid in many woods. Since oxalic acid dissolves iron, it’s a given that it will work on water stains too.
– Treat iron-based ink stains (in contrast to India ink, which is carbon-based. Carbon-based inks are usually permanent).
– Apply to pet stains. Pet urine is a stubborn stain but oxalic acid may work. Expect to repeat the bleaching two or more times.
– Brighten wood by applying oxalic acid. (Note that brightening does not include bleaching.)
– Create a saturated solution, adding the crystal oxalic acid to water gradually. Once no more will dissolve, the bleach is prepared. Rinse away the bleach with distilled water. Distilled water contains no iron, which can create new water stains. Neutralize the surface afterward with one quart distilled water mixed with 2 T. baking soda.

Two-Part Bleaches: For the strongest wood bleach possible — and to create certain special effects — choose a two-part bleach (available at your local hardware and home improvement stores). These are two separate chemicals sold together that, when applied one after the other, creates the bleaching reaction. Most two-part bleaches are comprised of sodium hydroxide (part A) and hydrogen peroxide (part B).
– Treat stains that fail to respond to chlorine bleaches or oxalic acid. Always neutralize the wood thoroughly before switching bleaches.
– Choose a two-part bleach if you want to actually bleach the wood, in contrast to stain removal. Two-part bleaches are the only bleaching product that will alter the color of your wood. The extent it will bleach the wood depends on the type of wood and other circumstances, however. Rinse away the bleach after the treatment is complete, using distilled water, rather than tap water. Neutralize the bleach with a mixture of 15-percent vinegar in 85-percent distilled water.

Sometimes other substances are used to bleach wood. For example, permanganate of potash is applied to wood when a purplish tint is desired. Chlorinated lime, on the other hand, is favored for bleaching walnut. (Look for it under the name “bleaching powder.”) These and similar lesser-used chemicals are available in specialized woodworking stores, as well as online.

Before You Bleach – Bleaching Tips for Wood

Take care and be mindful when bleaching wood. Bleaching is, by nature, a potentially hazardous process. Bleaches are caustic and emit strong fumes. Not only that, bleach can even damage your wood. As the bleach reacts with the wood it chemically weakens the wood fibers. This means the wood is softer and less resistant to wear and tear. Some woodworkers avoid it at all costs, while others value bleach in the right circumstances.
As well as this note of caution, keep these other points in mind:
– Some stains tell a story. Does the stain itself bother you enough to take a chance with bleach? If it doesn’t, think of it as a mark that illustrates your family’s life together.
– Spot-bleach stains when possible. The less the amount of area exposed to the bleach, the less work created — and also the less damaging to the wood.
– Start with the gentlest bleach, then progress in strength when treating stains. On the other hand, if you’re going for wood color removal, go right to the 2-part bleach.
– Use only the smallest amount of bleach needed for the effect – whether color or stain removal. Over-bleaching wood can damage it. Walnut, for example, tends to assume a greenish tint when overexposed to bleaches.
– Remove the existing finish before bleaching. Use either a liquid stripper or sand it until the finish is completely gone. For spot-bleaching, limit the stripper to the affected area. This prevents refinishing the entire surface as well.
– Test the bleach in a hidden area first to see the effect. If you’re not happy with the results, it’s much easier to hide that test spot. Some woods simply do not bleach well, and testing first may save you a lot of misery.
– Wear protection while stripping and bleaching. Safety glasses and rubber gloves help prevent exposure. Respirators or even dust masks help with strong fumes. Long sleeves and pants are also a good idea.
– Ventilate the area well while bleaching. Open windows, run fans, and leave doors ajar.
– Keep children and pets out of the area until the bleach is completely removed and neutralized.
– Avoid mixing chemicals. Use separate applicators and tools for each item.
– Have neutralizer premixed and available while you’re working, so that if you have an accident, it’s ready at hand.
– Allow the bleached item to dry completely before sanding and refinishing.
– Always wash your hands immediately after bleaching is complete.

Finish Ideas

Ready to use bleach in your more creative endeavors? Use oxalic to brighten your deck or patio outside. Or create special effects, such as taking the red out of mahogany (called blond mahogany), pickling your wood, creating a pearlized finish, or even match tones between two woods. The two-part bleaches in particular are useful in many situations. Plus, with a little practice, you may find you enjoy the creative experience of bleaching your woods.

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