How to Bleach Wood Properly – The Alternative to Staining or Painting Wood

Using lightning agents on wood has many uses. You may wish to remove water stains and marks from a surface. Perhaps you wish to lighten an older, dark wood stain before restaining with a lighter color. Maybe you’re chasing that trendy Scandinavian designer look by lightning the wood color. 

Whatever your reason, you need to know some tips and tricks to achieve the look you’re after and observe some serious safety precautions while handling the chemicals.

Four Methods To Use When Lightning Wood

  1. Sodium hypochlorite solution
  2. Calcium hypochlorite solution
  3. Sodium hydroxide & hydrogen peroxide (Two-Part Kit)
  4. Oxalic acid

Each method has advantages and disadvantages, in addition to specific precautions due to the chemical substance. Depending on your use, one of these is preferable over the others.

For those of you wishing to actually remove the natural color from wood, Method #3 is the one you’re after. The others will remove stains and marks only.

Critical Safety Precautions

Before we get into the details, let’s cover some common safety rules for all these methods.

  • These chemicals must not come into contact with metal containers. Use only glass to hold the solutions, or you can use containers made from polyethylene, high-density polyethylene, or polypropylene.
  • Use gloves when handling chemicals. These chemicals are highly corrosive to the skin, and they’ll either dissolve the surface of your skin or cause chemical burns. I’ll repeat this warning – use gloves!
  • Use eye protection. If it burns or dissolves skin, it’ll do the same to the eyes, except the damage will impair or destroy your sight.
  • Use these chemicals in a well-ventilated space or open windows or doors; if necessary, use a fan. Do not breathe the fumes.
  • Cover up. Long-sleeved shirts and long trousers will assist in protecting you against splashes.
  • Do not mix chemicals. If you intend to add other substances to the wood, ensure it is neutralized and dry before you do!

With that said, let’s dive into the specifics of each method to assist you in selecting one that meets your needs.

Sodium Hypochlorite Solution

Sodium Hypochlorite
Sodium Hypochlorite. Photo: Amazon

What is it?

We best know sodium hypochlorite in its diluted state as household bleach. Household bleach is usually sodium hypochlorite, an alkaline liquid, diluted to be between 3% to 8% strength. When used in these low concentrations, household bleach will remove stains from wood without much lightning of the timber, and you may need several applications to remove the stains completely.

Why would I use it?

Chlorine-based bleaching agents are excellent at removing dye-based stains, and they will remove the stain without altering the color of the wood. When used on pigment-based stains, they are usually ineffective. 

How should I apply it?

Ensure the wood is clean of dust and dirt, and wipe it down with a lint-free cotton cloth soaked in either water or denatured alcohol. Allow the surface to dry thoroughly, possibly a day or two, before beginning the bleaching process.

Using a brush, apply the sodium hypochlorite to the surface, ensuring total coverage. Do not let the sodium hypochlorite pool in any one spot. Leave overnight and, if necessary, apply a second coat. If you don’t achieve the expected results, further applications of sodium hypochlorite will not help. Allow the last coat to dry for four hours before neutralizing.

Neutralize your wood by wiping the surfaces down with a cotton rag soaked in water. Wipe dry with another cloth, then wipe down the surface again with water. Finally, wipe dry and allow the wood to dry naturally for a day or two. Sand lightly to remove the raised grain that will have occurred from the chemical action, then apply your surface treatment.

What extra safety precautions must I follow?

Some teachers of wood bleaching suggest neutralizing the surface with a mix of water and vinegar. Please do not do this. When you mix sodium hypochlorite with vinegar or acid, it gives off chlorine gas. While the mixtures are heavily diluted, I simply wouldn’t risk it.

Where can I buy it?

You can try ordinary household bleach or buy this laboratory-grade 5% solution.

Calcium Hypochlorite Solution

Calcium-Hypochlorite Super Charge Shock
Calcium-Hypochlorite Super Charge Shock. Photo: Amazon

What is it?

Calcium hypochlorite is found in hardware stores as pool chlorine. Usually sold in white granules, you’ll need to mix these with water.

Why would I use it?

Calcium hypochlorite is far more potent than sodium hypochlorite for lightning or removing stains. Once again, it’s excellent at removing dye-based stains and will remove the stain without altering the color of the wood. When used on pigment-based stains, it’s usually ineffective.

How should I apply it?

Create a saturated calcium hypochlorite solution by gradually mixing the granules with warm water until no more granules dissolve. The mixture will begin to foam, and the calcium hypochlorite will begin to decompose immediately, so only mix what you need as it loses effectiveness rapidly.

Once you have the mixture, follow the same instructions as given above for applying sodium hypochlorite.

Once dry, sand lightly to remove the raised grain that will have occurred from the chemical action, then apply your surface treatment.

What extra safety precautions must I follow?

Some methods of wood bleaching suggest neutralizing the surface with a mix of water and vinegar. Please do not do this. When you mix calcium hypochlorite with vinegar or acid, it gives off chlorine gas. While the mixtures are heavily diluted, I simply wouldn’t risk it.

Where can I buy it?

Use these pool chlorine granules, or try your hardware store. 

Sodium Hydroxide & Hydrogen Peroxide

Daly's Wood Bleach Solution Kit
Daly’s Wood Bleach Solution Kit. Photo: Amazon

What is it?

Normally sold as a kit, this product comprises a Part A and a Part B. One part will be sodium hydroxide, otherwise known to us as caustic soda, the other part will be hydrogen peroxide, a potent bleaching agent. Combined, the two will remove the natural color from timber.

Why would I use it?

Of the four methods discussed here today, a sodium hydroxide and hydrogen peroxide mix is the only solution that genuinely blonds or bleaches wood, removing its natural color. The others will remove stains.

Used when you wish to apply decorative finishes to wood or to achieve that bleached Scandinavian look.

How should I apply it?

Different products require different applications. Some require the application of Part A, followed by Part B. Others require you to mix the two parts in equal measure. Follow the instructions on the kit that you purchase. 

Make sure your application to the wood is even. Once you have the look you require, you must neutralize the chemicals. Most instructions will tell you to use a mild acid such as white vinegar to neutralize. However, be sure to follow the instructions given on the package.

Once the surface is dry, sand lightly to remove the raised grain that will have occurred from the chemical action, then apply your surface treatment.

What extra safety precautions must I follow?

Just follow the general instructions at the beginning of this article, and you shouldn’t go wrong.

Where can I buy it?

You can purchase a kit here

Oxalic Acid

OXALIC Acid 99.6%
OXALIC Acid 99.6%. Photo: Amazon

What is it?

Oxalic acid is an organic acid used for cleaning or bleaching. When used for bleaching, it comes as crystals to be dissolved and diluted in water before use.

Why would I use it?

Helpful in removing black water stains, rust stains, and alkali stains from strippers. It will not change the color of the wood.

How should I apply it?

Remove all surface coverings such as varnish, polish, or wax from the timber. It’s best to use a stripper to be sure nothing will block the action of the oxalic acid.

Dissolve the crystals in hot water until the solution is saturated, meaning that no more crystals will dissolve. While still warm, brush the solution over the entire surface, not just the stains. Allow the surface to dry back to crystals.

Remove the crystals and neutralize the acid by washing the surface with running water or a well-soaked cotton rag. Be thorough; it’s best to repeat this washing action several times. Allow the timber to dry.

You can repeat the oxalic acid treatment several times if needed to remove all the stains. Any remaining marks should now sand out easily once dry. Apply your chosen surface covering.

What extra safety precautions must I follow?

Wear a face mask when mixing the crystals and when washing the surface. If you brush the crystals into the air and breathe them in, you’ll find yourself coughing and choking from the acid in your lungs. Mask up!

Where can I buy it?

Florida Laboratories sells various sized packs.

William Stewart

The proud owner and lead writer of WoodImprove.com. Started writing in 2018 and sharing his love and passion for wood treatments and crafts.

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