| ================= SODA ASH ================= In dyeing with Fibre Reactive Dyes, soluble salts of sodium release sodium ions which help drive and attach the dye to the fibre. In fact any soluble sodium salt will do so that includes common (table) salt and the forms of sodium carbonate, one of which is commonly known as soda ash. Sodium Carbonate is available in two distinct forms and to differentiate one is known as Soda Ash and the other as Washing Soda. The first is anhydrous (contains no combined water), it normally looks like a white granular powder and has been dried out at quite a high temperature. The other has 10 molecules of water combined with each molecule of sodium carbonate, and is made from a solution in water, it is in the form of large glassy crystals. The main difference is that it needs about 5 times the weight of the latter to give the same amount of sodium in the solution. This form is the type of sodium carbonate which is normally bought in the shops - as washing soda. Professionally it is worth (ie cheaper for the amount of the working chemical purchased) getting the anhydrous form (Soda Ash), but for the occasional use then washing soda is more easily obtained. One caveat is that sometimes washing soda has added bleach, but very rarely. Now Sodium Bicarbonate, which is also known as baking soda, is another form of soluble sodium compound, but comparatively expensive. Ian Bowers --------------- If you are looking for soda ash, it is often found in pool supply stores as pH up. It is usually cheaper than in the grocery stores, which may have added brighteners as well. It certainly is called different things in different parts of the country and is usually a good idea to know what the actual chemical name is for much of this stuff. Tricia --------------- |
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| (Sodium Carbonate is available in two distinct forms and to differentiate one is known as Soda Ash and the other as Washing Soda.) |