Effective Bath Bleaching

In order to do bath bleaching effectively, you should know what it can do and what it cannot do. You should know the fabric you are bleaching and use of correct concentration, heat and time for bleaching.

FACTS ABOUT BLEACHING

Bleaching entails the use of oxygen to change or make the molecules of staining or yellowing colorless. The two major types of bleaching are oxidizing and reducing.

Oxidizing bleaches put oxygen into a fabric or stain and make it colorless. Reducing bleaches are completely opposite since they remove oxygen from a stain and also make it colorless.

Oxidizing bleaches work primarily on whitening fabrics and removing last traces of tannin, protein and dye. Reducing bleaches work primarily on dye but also have characteristics of whitening fabrics and removing other staining. Bleaches are not effective on soil, dirt and dryside stains.

RULES OF BLEACHING

1. Metal accelerates bleaching. Always bleach in a non-metallic basin or pail.
2. Every 18 degrees rise in temperature doubles the chemical action. Use water temperatures at 100℉.
3. Oxidizing and reducing bleaches are chemically opposite. Never put both in the same bath.
4. If a color change occurs with an oxidizing bleach rinse and use a reducing bleach. The same process should be done if a reducing bleach causes a color change.
   5.Test safety of bleach before immersing garment in bleach bath. Also test effectiveness of bleach on fabric and stain.
5. Always add a lubricant when bleaching for better penetration of bleach.
6. Rinse and neutralize bleaches when necessary.

HYDROGEN PEROXIDE

Hydrogen peroxide is characterized by a chemical formula that releases free oxygen. It is near to neutral and does not have to be neutralized. It is the safest bleach to use when bleaching off color wools, silks and color sensitive fabrics. It can whiten fabrics and remove last traces of tannin and protein. For bath bleaching, use a 14% concentration or a premix sold by some manufacturers.

BATH METHOD

1. Add 2 ounces of peroxide per gallon of water and one ounce of lubricant per gallon of water.
2. Water temperature -100℉
3. Soak for ½ hour
4. Rinse

SODIUM PERBORATE AND SODIUM PERCARBONATE

These two oxidizing bleaches are similar in nature and both alkaline based. Drycleaners have found that sodium percarbonate is a little more effective and provides better results. Sodium percarbonate also dissolves easier in cooler water. These bleaches are long term bleaches and garments can be soaked overnight. It is effective for whitening fabrics and last traces of staining.

BATH METHOD

1. It may be necessary to use hot water to dissolve the bleach but bleaching temperature when soaking should be 100oF.
2. Use 2 ounces of bleach per gallon of water.
3. One ounce of neutral lubricant per gallon of water.
4. The soaking time is gauged according to fabric and staining.
5. Soak overnight to whiten fabric.
6. Rinse after bleaching.
7. Make up a sour bath of one ounce of acetic acid or oxalic acid per gallon of water. Soak for 10 minutes and rinse. Use the lubricant in the sour bath to ensure better penetration and mixing.

SODIUM HYPOCHLORITE

A strong oxidizing bleach that is alkaline by nature, it cannot be used on wool and silk. Household bleach comes in concentration of 5.25%. When using, we dilute the 5.25% to 1%. Effect bleach for removing mildew, many stains and whitening fabrics such as cotton, linen and rayon.

BATH METHOD

1. Use one ounce of 1% bleach per gallon of warm water.
2. Add a neutral lubricant
3. Rinse
4. Use an acid bath (oxalic or acetic). Use 1 ounce per gallon of water with a neutral lubricant.
5. Rinse
   The acid bath is used to accelerate the bleach so it is removed from the fabric.

POTASSIUM PERMANGANATE

It is a strong oxidizing bleach, comes in purple crystals or sold in liquid form by some manufacturers. It has a use for removing mildew, whitening fabrics and removing last traces of difficult protein, tannin, ink and dye. It may leave a brown discoloration that can be removed by hydrogen peroxide and some reducing bleaches.

BATH METHOD

1. Add bleach according to manufacturer’s instructions.
2. Add a synthetic detergent.
3. Soak 5 minutes
4. Rinse
5. Remove last traces by making up a bath of peroxide and acetic with a little detergent.
6. Rinse again

REDUCING BLEACHES

These bleaches remove oxygen from fabrics and stains. They are very effective for dye stains and sometimes whitening fabrics. All reducing bleaches are acid by nature.

SODIUM BISULPHITE
It is a very mild reducing bleach and sometimes can be used on fabrics with color.

BATH METHOD

1. One to two ounces of bleach per gallon of warm water (100℉).
2. Add a synthetic detergent.
3. Soak 15 minutes
4. Rinse thoroughly

SODIUM HYDROSULPHITE
It comes in powder form and sold by various manufacturers. It removes dye and whitens fabrics. It is also an anti-chlor which restores yellowing caused by chlorine bleach. It has a strong pungent odor.

BATH METHOD

1. Use 1 to 2 ounces per gallon of warm water.
2. Add 2 ounces of synthetic detergent per gallon of water.
3. Soak 10 to 15 minutes
4. Rinse thoroughly

TITANIUM SULFATE STRIPPER

1. It is purchased as a purple liquid
2. It removes dye stains when other strippers do not
3. It does not whiten fabrics
4. It reacts with other chemicals to form discoloration, The discoloration can be removed with rust remover.

BATH METHOD

1. Add titanium according to manufacturer’s directions or judge concentration by intensity of color.
2. Add a synthetic detergent
3. Soak a short time, depending upon color of fabric and stain. A colored fabric may only need a few seconds in a diluted solution.
4. Rinse in warm water
   Some manufacturers may recommend adding a little rust remover to the bleach solution to lighten the color of the bleach and intensify the strength of the bleach solution. Thorough rinsing is very important for this mixture.