National Clothesline

For can’t-fail bleaching, remember these four keys: concentration, acceleration, neutralizing and testing.

When I teach classes on bleaching, I find that many cleaners are not using the bleaches properly. When I test the hydrogen peroxide on the spotting board, I find that the chemical has expired and is just plain water.

Some cleaners who are using sodium perborate are not using the right concentration nor using it properly.

Titanium sulphate can be used on poorly dyed fabrics if used at the right concentration.

Facts. This is oxidizing bleach composed of water and oxygen. It is not chemically acid- or alkaline-based. It is used for the last traces of tannin, protein, ink and dye. It is very effective for removal of scorch.

Concentration. Hydrogen peroxide can be purchased 30% 100 volume. This is too strong for bleaching since it can deteriorate fabrics. The best concentration to use is 3% 10 volume (antiseptic) and 6% 20 volume (hair bleach).

Acceleration. All bleaches are accelerated by heat. Ammonia or any alkali will accelerate hydrogen peroxide. The 3% 10 volume can not reach the effectiveness of 6% 20 volume even when heated.

Neutralizing. Hydrogen peroxide, when used without an alkali does not have to be neutralized. When used with ammonia or alkali it does. After using peroxide with ammonia, flush and apply a mild acid such as acetate or tannin formula.

Time. If you apply 6% peroxide to a stain and keep applying it for 20 minutes, you will achieve a very effective bleaching. Exposure to ordinary light plus the time factor creates a more effective bleaching than when heated up.

This does not work with the 3% 10 volume. You do not add ammonia to the time method of bleaching.

Bath Bleach. Peroxide can be used as a bath bleach. In warm water add 2-4 ounces of 6% peroxide per gallon of water. Add a little detergent to the bath for better penetration.

Testing. To test whether the peroxide has potency, apply peroxide to a q-tip and then titanium sulphate. If it turns orange, the peroxide is good to use. Fabrics should be tested before using.

Even white fabrics should be tested since the area can turn whiter.

When used on silk and wool, you should note that a 3% 10 volume with ammonia is more hazardous to the dye than a 6% 20 volume using no ammonia.

Facts. This is an oxidizing bleach that is alkaline in nature. It is similar to hydrogen peroxide in chemical composition, but it is used differently. Sodium perborate comes in powder form and dissolves in hot water rather than cold water. It releases oxygen slowly which makes it useful as a long time soaking action for whitening fabrics.

It can also be used as a spotting board bleach and can be effective for last traces of tannin, protein, ink and dye.

Concentration. Sodium perborate is found in many detergents, but can also be obtained in a stronger form from your chemical supplier. When sodium perborate in a strong form is used as a spotting board bleach, it has an effective reaction on staining.

Acceleration. Sodium perborate is accelerated by heat and alkali. Since it is alkaline in nature, it does not need additional alkali for acceleration. It releases oxygen slowly and is a good whitening agent for use in a bath.

Neutralization. It is neutralized by an acid because of its alkaline nature.

Usage. When using sodium perborate as a bath bleach, use the amounts designated by the manufacturer, according to the concentration of the bleach. When mixing this bleach, use warm or hot water and add a detergent for better penetration.

On the spotting board, a paste can be made and it can be heated with the steam gun. Flush and neutralize with a mild acid.

Testing. All colors on fabrics should be tested because of the alkaline nature. Wool and silk are especially sensitive to this bleach. Any color may fade or bleed in a bath bleach.

Time. This bleach can be used for general wetcleaning or soaking garments overnight.

Facts. This is an oxidizing bleach similar to sodium perborate. It does not have exactly the same characteristics as sodium perborate. Sodium percarborate dissolves easier in cold water and releases oxygen quicker than perborate.

It is used as a whitening agent especially for wool and silk. It is effective for last traces of tannin, protein, ink and dye.

Concentration. The pure sodium percarbonate can be ordered from your chemical suppliers. This is much more effective than the sodium percarbonate used in detergent mixtures. The pure sodium percarbonate also has quicker activation making it effective on staining.

Acceleration. It is also accelerated by heat and is alkaline in nature. It does not need additional alkali for acceleration. The natural activation of pure sodium percarbonate also reduces the need to heat it.

Neutralization. It is neutralized by rinsing and mild acid. When using as a bath bleach, use the amounts designated by the manufacturer according to the concentration of the bleach.

Mix in cool water and add a detergent for better penetration. When used as a spotting board bleach, make up a paste and then heat the area with a light feather of steam. It can also be left on the stained fabric for a period of time before flushing.

Testing. When soaking garments with color, you must be aware that all colors can bleed and fade due to the long time soaking period. There is no accurate pre-testing that can be done when garments are soaked for a long period of time.

Time. This bleach can be used for general wetcleaning or for soaking garments overnight.

Examples of manufacturers producing more concentrated oxygen bleach would be the following:

(1) Cleaners Chemical Corp manufactures number 3.

(2) Metro Chem manufactures satin 2

We’ll continue discussing bleaching next month.