The Bleaching Activity of a Specific Toasil quality should, as far as possible, remain constant. Guaranteeing this is one of our most important tasks. To determine whether this is being done, bleaching tests are carried out for comparison with a standardised bleaching earth and the bleaching earth which is to be tested. To do this, within the scope of our international Süd-Chemie standard methods, a test oil is used, difficult to bleach and defined according to acid value and colour. The colours of the bleached oils can be compared colorimetrically with one another, and tested in the spectral photometer, this ensures that even the smallest colour variation can be reliably detected. In order to achieve a better assessment of the bleaching activity for our client, the comparison bleaching tests are often also carried out with the corresponding oil samples from our customers' refineries.
The assessment of these quality tests, over many years, provides an impressive picture of the consistency of quality of our Tonsil bleachinq earths, and of the considerable fluctuation in the oil qualities of the different oil seeds.