Bleaching colored cloth

Sometimes rather than adding color to a product, it is necessary to take color away. We bleach our clothes, our hair, and sometimes even our food. Most often chemicals react with colorful compounds to make them colorless through a process called oxidation. 

It is a well-known fact that dry chlorine does not bleach dry cloth, but that chlorine water bleaches it easily. It is known that chlorine hydrolyzes (see Preparation 36), and the bleaching is attributed to the hypochlorous acid, which, on account of its instability, is a strong oxidizing agent and oxidizes the colored substance to a colorless one. 

Hypobromites. Add a few drops of bromine to 2 cc. of 62V NaOH diluted with 5 cc. of water. The red color of the bromine disappears. Dip colored cloth and litmus paper in this solution and then in dilute H2SO4, to show that it bleaches in the same way as a hypochlorite solution. 

The home method of bleaching is to use chlorine water, which is chemically similar to hypochlorous acid. Care must be taken when bleaching stains from colored cloths, because the dye might be removed as well as the stain. Only cotton, linen, and heavy canvas-type cloth can be bleached successfully with chlorine water. 

Materials Bleaching powder, sodium carbonate, colored cloth, potassium hydroxide, chlorine, splinter. 

Raw lac is first treated to remove water-soluble carbohydrates and the dye that gives lac its red color. Also removed are woody materials, insect bodies, and trash. It is further refined by either hot filtration or a solvent process. In the heat process, the dried, refined lac is filtered molten through cloth or wine screens to produce the standard grades of orange shellac. In the solvent process, lac is dissolved and refluxed in alcohol solvents, filtered to remove dirt and impurities, and concentrated by evaporation. The lac can be further decolori2ed in this process to produce very pale grades. Bleached shellac is prepared by treatment with dilute sodium hypochlorite and coalesced into slabs. 

MOISTEN THE CLOTH AND AGAIN HANG IT IN THE CHLORINE. SOON THE COLORS FADE-ONLY TRULY FAST" COLORS REMAIN. CHLORINE, IN CONTACT WITH WATER, COMBINES WITH THE HYDROGEN AND LIBERATES OXYGEN. THE LIBERATED OXYGEN DOES THE BLEACHING. 

Mitsubishi Chemical Corp. developed a water-based ink composed of photo-chromic-containing capsules and an aqueous polymer binder.46 The average particle size of the capsules containing photochromic spirooxazine and antioxidant was 20 pm. By using this ink composition, cotton clothes could be screen printed. The printed part showed coloration within 10 s when exposed to sunlight and exhibited good fatigue resistance. Furthermore, it bleached within 15 s in the dark, and this process was observed repeatedly. 

Filtration—After an adsorbent has selectively captured the impurities, it must be removed from the oil before it becomes a catalyst for color development or other undesirable reactions. Filtration, the separation method most often used for spent bleaching media removal, is the process of passing a fluid through a permeable filter material to separate particles from the fluid. Examples of the filtration materials used are filter paper, filter cloth, filter screen, and membranes. Filter aid, such as diatomite, perlite, or cellulose, are usually used in conjunction with the permeable filters for surface protection. Traditionally, either plate and frame or pressure-leaf filters have been used for spent bleaching media removal. Currently, self-cleaning, closed filters that operate on an automated cycle are available. 

Bleach removes stains from clothing by oxidizing colored molecules to form colorless molecules. 

This woman is using bleach to launder clothing. Not only can bleach remove stains, but it can act as an agent to remove color. 

Boil a second piece of dyed silk in a solution of chlorine water. (7) What effect was produced on the color (8) Was the strength of the fiber of the cloth effected Rinse the cloth under the tap and boil it in the solution of potassium chlorate. (9) Was the color restored (10) To what class of reactions does the bleaching process belong (11) What advantage does it possess over bleaching with sulphur dioxide ... 

Some bleaches function as a strong oxidizing agent, thus it oxidizes the chro-mophores, or color molecules, in your clothes and turns them white. Other bleaches are strong reducing agents, and they break the bonds in the chro-mophore, which also takes the color out of the clothing. 

Similar to bleach, ammonia can whiten the color of materials. Ammonia can be gathered by concentrating urine this was used to clean clothing, as well as make tooth paste and mouthwash by the ancient Romans. 

In Berthollet s day the love of color and personal adornment was as strong as ever, and the demand for dyed textiles came from those who could afford it. Before dyeing textiles however they had to be bleached, which required spreading the cloth on the ground. This was not only labor intensive, but it kept fertile fields from being tilled. Berthollet developed a chemical bleaching process that used chlorine... 

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