PREPARATION OF WHITENING AND DISCOLORING BATHS.
As already mentioned, the easiest and most reliable way is to use ready-made bleaching agents for bleaching and discoloration, which can be purchased in specialist stores, of course, the method of use attached to each preparation should be followed exactly. For whitening, we use an appropriately diluted solution. If you want to whiten white underwear or clothes, you can also use the previously mentioned ones, household chemicals, namely hydrogen peroxide and potassium hypochlorite solution.
Tips for using hydrogen peroxide.
Hydrogen peroxide is sold as a 3% or concentrated 30% solution. If we are going to prepare a whitening bath from a few liters of water, then a concentrated solution should be used. Bottle containing 50 g of concentrated hydrogen peroxide solution (perhydrolu) enough for 2 liters of bleaching bath, while the same amount of baths should be used up 1/2 liter of 3% hydrogen peroxide. Concentrated hydrogen peroxide is corrosive, it must therefore not be allowed to splash or come into contact with the skin. You have to handle this preparation very carefully.
A little ammonia or a little dissolved borax is added to the prepared whitening bath just before it is used, which increases the intensity of oxygen evolution and the whitening effect.
The whitening process is carried out warm at a bath temperature of approx. 30°C. Bleached garments can be left in this bath for several hours, without fear of damaging the fabric. Even wool can be treated with the above bleaching bath (e.g.. yellowed white wool pullover).
Directions for use of potassium hypochlorite solution.
It should be emphasized once again, that hypochlorites are not suitable for bleaching wool and natural silk, Dederonu, Grisuten, Elana and copper artificial silk, because they have a harmful effect on these fibers. Unfortunately, the degree of concentration of the potassium hypochlorite solution available on the market is very different. These provisions take into account concentrations ranging from 35 by 40 ° Rafting. Bottle containing 50 g of potassium hypochlorite solution is sufficient for 10 liters of bath. First, the hypochlorite solution is poured into clean water, then the solution should be mixed well and only then put underwear into the bath - thanks to this, the whitening bath works more evenly. Duration of the bath: from 15 do 30 minutes. The bath temperature should not exceed 25 ° C.
Bleaching is followed by rinsing in an acid bath, i.e.. in water with a little vinegar, then in clean water, and finally the linen is placed in the sodium thiosulphate solution (antichlorine) in relation to approx. 2 g of sodium thiosulfate per 1 liter of water. The linen is left in this solution for approx. 15 minutes, then it is rinsed again, to thoroughly remove residual chemicals from the fabric.
It happens, that the washed underwear is not nice, gray shade. The reason for this is calcium soap, that is, a chemical compound, which is created by the use of soap for washing in hard water. Due to their lipophilic properties, products made of synthetic fibers also bind fat-soluble impurities. It is manifested on white fabrics in the form of a gray shade. In such cases, additional whitening is necessary.
The usual gray coating on washed fabrics is removed by using an acid bath, containing approx. 1% acetic acid. The vinegar used in the household has a concentration of 6 do 10%. On 10 liters of acid bath are added from 1 do 1,7 liter of vinegar. The underwear is left in this bath overnight, the next day, it should be rinsed several times in clean water. Additional bleaching of linen in the sun brings very good results.