In order to prepare an elegant, dark calf skin nubuck and velour, the selection of the raw material is quite important. Since defects, neck wrinkles and draw will show up after the buffing operation, the quality of the wet-blue gives an indication if it is possible to achieve satisfactory results.
For this leather, calf skin wet-blue from Poland was used. The crusting operation contains a retanning with SELLATAN CF new and TANNESCO HN gran. as well as SELLASOL MI for filling and softness.
After the neutralisation to pH of 5.9 and the addition of MAGNOPAL PGN, the fatliquoring is carried out. The combination of CORIPOL MB, CORIPOL MK, EUPILON IN and BORRON SAF has to be carefully adjusted according to the raw material. It is important to achieve a good penetration of the fatliquor and still keep enough surface lubrication to achieve a good buffability. The amount of CORIPOL MB plays an important part and has to be adjusted to the local conditions, such as water hardness, float pH, amount of chrome in the float, etc.
After the buffing operations, the wetting back and washing with BORRON SAF helps to reduce the amount of dust in the bath before the dyeing processes.
The first dyestuff addition of SELLA FAST Black FT comes in combination with INVADERM AL and SELLA FIN Black P to build up a rich shade before the top dyeing with SELLA FLUID Black M-L. The washing processes between the dyeing and fixation steps help to remove unbound dyestuff. After the chrome fixation, the top fatliquoring with EULINOL TMS and RODA mod 2081 helps to intensify the shade and enhance the handle after the milling and toggling operations.