One of the most useful spotting agents around is hydrogen peroxide. Most cleaners do not use it to its full potential. One of the problems that they encounter is that they do not activate it properly or they use concentrations not suitable for the stain removal process that they are doing. Hydrogen peroxide is simply water with an extra oxygen (H2O2). The extra oxygen is capable of combing with staining matter or fabric producing a chemical change. The fact that oxygen is added to the fabric makes hydrogen peroxide an oxidizing agent. Hydrogen peroxide can be obtained in various strengths.
- 3%, 10 volume (medicine)
- 6%, 20 volume (hair bleach)
- 30%, 100 volume (commercial use)
The recommended strength for bleaching is 3% or 6%.
Hydrogen peroxide can be used to remove many different types of staining which is not possible with other bleaches. It is effective in removing oxidized tannin, protein, blood, dye and mustard stains. Peroxide is also effective in neutralizing some discolorations caused by titanium sulphate. The advantages over chlorine based bleaches is that it can be used on wool and silk. Remember to test dyes and fabrics before using peroxide since peroxide is a bleach and can produce discolorations.
ACTIVATION
There are different ways of using peroxide and each way produces a different effectiveness. For example, I can heat peroxide with ammonia and not obtain the same stain removal as when I expose it to light and air. Trial by error will determine the success.
- Heat – Every 10 degrees rise in temperatures can double the chemical action. A light feather of steam activates and accelerates the bleaching process.
- Alkali – Hydrogen peroxide is accelerated by alkali. Ammonia or addition of protein formula increases the chemical action. This must be used with caution on wool and silk.
- Peracetic Acid – Hydrogen peroxide when combined with acetic acid forms peracetic. This can be used to bleach certain fabrics that ammonia cannot be used on. Hydrogen peroxide plus acetic acid is also used to reduce the discoloration formed when potassium permanganate bleach is used.
- Hydrogen peroxide plus sunlight – When water is combined with the ultra-violet rays of sunlight it forms hydrogen peroxide. When peroxide is exposed to sunlight a high degree of oxidation can be obtained making stain removal more effective. Hydrogen peroxide when exposed to sunlight should be applied in a 3% strength and the time period should be carefully controlled. Over exposure by peroxide to sunlight can result in oxidation, yellowing and loss of fluorescent dyes. This method has been used in my analysis lab for many years in order to remove many difficult stains.
- Hydrogen peroxide plus enzymes – Hydrogen peroxide is decomposed by enzymes and will decompose enzyme related staining. We know that the enzymes in blood will cause peroxide to foam and the blood as well as the peroxide is decomposed. When brushing your teeth, the enzymes in saliva will foam peroxide based toothpaste. We also know that strong peroxide on your skin turns white from combining with the enzymes on your body. When peroxide is added to some enzyme based spotting agents it is a highly effective way of removing many protein based staining.
- Sodium percarbonate and sodium perborate – They are powder bleaches and both release hydrogen peroxide. The advantage of using this for spot bleaching is that they are concentrated and will provide more localized bleaching and remain in the fabric longer. The area is dampened and the powder is applied with moisture using a paste. When heated the bleaching is more concentrated and often more effective.
- Air and light-Peroxide is highly effective when applied and left exposed to air and light for a period of time. This method is used with a 6% concentration of peroxide. Apply the peroxide re-apply every half hour. Flush after use.
BATH BLEACHING
Hydrogen peroxide can be used for bath bleaching in a form of sodium perborate, sodium percarbonate or just liquid hydrogen peroxide. 6% hydrogen peroxide can be added to warm water in a bucket or tub in the ratio of 2 ounces per gallon of water. Peroxide bleaching is effective when a near neutral water solution is desired such as for wools and silks. Peroxide bleaching is used for a short time period (1 hour). Sodium perborate or percarbonate can be added to warm water in the ratio of two ounces per gallon of water. This is used as an overnight bleaching. When bath bleaching a neutral detergent should be added so better penetration of the bleach can be obtained.
TESTING FOR PEROXIDE
When peroxide remains on the spotting board it decomposes from exposure to light and heat. To test if your peroxide is effective apply a few drops on a towel and add titanium sulphate or stripper to sample. If the sample turns orange the peroxide is strong and effective. Yellow means it is weaker and no change in color means your peroxide is spent.
