Safer Bleaching For Colored Fabrics

Most drycleaners that I encounter in my training and consultations understand bleaching but only for light or white fabrics. Bleaches remove stains by either adding or removing oxygen from the fabric. The bleaching process is used to whiten clothes and remove last traces of stains such as protein, tannin and dye. Understanding the concepts of all bleaching will make the drycleaner aware of what is safe to colored fabrics and what is not safe. The application of the bleach is also important for the safety of the fabric.

CHARACTERISTICS THAT MAKE BLEACHES MORE AGGRESSIVE

It must be understood that heat accelerates bleach. Every ten degrees increase in temperature doubles the chemical action. That means if you heat a bleach up from 90-100°F you double the chemical action making it twice as strong. The chemical nature of the bleach also makes the bleach dangerous.

(1) Sodium percarbonate and sodium perborate – These are mild bleaches but the alkaline nature of the bleach makes it dangerous to dyes on fabrics. For example-if I used these bleaches on a colored silk the dyes will discolor due to the alkalinity of the bleach. If I apply heat to this bleach, it will become even more aggressive.
(2) Sodium hypochlorite – This bleach is highly alkaline in nature and will remove dye from a fabric even in a diluted state. The alkalinity of the bleach also makes it unsafe on wool and silk.
(3) Potassium permanganate – This is a strong oxidizing agent that is rarely safe on colors. It is acid by nature and must be neutralized to remove discolorations that the bleach forms. The agents used to neutralize the bleach also make the bleach more aggressive.
(4) Sodium hydrosulphite – This is a strong reducing bleach that is used to remove dye from fabrics. It is highly aggressive and will remove color from fabrics.
(5) Titanium sulphate-This is an acid based reducing bleach that is used to remove dye from fabrics. The chemical nature of the bleach makes it unsafe to most dyes on fabrics.

SAFE BLEACHING (OXIDIZING AGENTS)

Hydrogen peroxide (3%) – Hydrogen peroxide is made up of 2 parts hydrogen and 2 parts oxygen. The extra oxygen is what does the safe bleaching. Most cleaners using this bleach will accelerate the bleach with ammonia or protein formula. This combination will make the bleach more aggressive and the addition of the alkali will cause colored fabrics to discolor. In order to use hydrogen peroxide safely it must be used in a 3% concentration. It also should be used in a spray bottle. If you go to the drug department of stores you will be able to purchase hydrogen peroxide in a spray bottle designed for cuts and bruises.

APPLICATION

If you have a colored fabric with a yellow oxidized stain or a similar oxidized stain, then lightly spray the stained area. Hang the garment up in a well ventilated room. Do not hang the garment near heat and do not apply chemicals to the bleach. You may have to re-apply the application several times until the stain disappears. The time it takes for the bleach to work is not wasted since you can be doing other things. The good thing about using hydrogen peroxide is that once the bleach dries it dissipates into plain water. This means that it does not have to be flushed or neutralized.

SAFE REDUCING BLEACHES

Sodium Bisulphite – This bleach comes in powder form and is the safest reducing bleach that there is. It is acid by nature and it must be rinsed thoroughly after use. Any bleach remaining in the fabric can produce color loss. Although it is a very mild bleach it should be tested on color fabrics if color fastness is a factor. It can be used on a stain with the straight powder and moistened with the steam gun. It can also be dissolved in water and it is then applied to a fabric. Sodium Bisulphite is very effective for removing dye and also some stains such as wine. After use it should be flushed thoroughly but it does not have to be neutralized.

SAFE BATH BLEACHING

(1) HYDROGEN PEROXIDE
Bath bleaching using any bleach can be hazardous to color on fabrics because the soaking action tends to bleed dye. The safest bleach in a bath to use is hydrogen peroxide. Use 4 ounces of 6% hydrogen peroxide per gallon of water. Soak for 10-15 minutes. Then rinse.

(2) SODIUM BISULPHITE
Bath bleaching using sodium bisulphite is the safest reducing bleach to remove dye or stains such as wine. Use 2 ounces of sodium bisulphite per gallon of water. Soak for 10 or 15 minutes and then rinse thoroughly.