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Mixing Of Mother And Wash: The discharge procedure, which may be assisted by air blow-back, leaves no heel of cake and thus in situ Filter medium cleaning is readily performed. As all liquors are kept separate, there is little unwanted mixing of mother and wash liquors and countercurrent washing can be very good. Tilting pan filters are available with total Filter cloth areas up to 200 m2, however, many of their inherent advantages are offset by their mechanical complexity and high capital cost.
Dependent on the properties of the solids forming the cake, the presence of the heel can have undesirable consequences for future cycles and necessitates the use of more open Filter media with the potential for cloudier filtrates. As the filtration surface is not physically divided into individual sectors some short-circuiting of the feed may occur as well as unwanted mixing of the wash and mother liquors. Cloth washing is difficult and must be performed off the filter. Although cloth area can be up to -200 m2, alignment difficulties usually restrict machine size and the available Filter area to less than 20 m2.
In mixing colors with white, gray, or black pigments one will usually find that the resultant colors turn slightly blue. There is an unseen bluish element in these neutral pigments. Mixing any of these pigments with blue, the additional tinge is not visible; but mixing them with red or yellow, a purplish or greenish tinge will respectively be noticeable. This must be corrected in such mixtures by the addition of a slight amount of orange or yellow in the first case and orange or red in the second. The exact amount of the complement to be added must be estimated by observation and trial and error. There is no scientific method of exactly accomplishing this correction.
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