Pretreatment Linen / Flax fabric
The scouring of linen is associated with number of problems such as weight
loss, release of cations from salts into solution and loss in strength. If the released
cation is iron, this can lead to cationic tendering during bleaching. This problem
can be minimised by adding suitable chelating agents in the scouring bath and thus
sequesters any cations released from the proteins.
Traditionally, long slow processes are carried out to obtain correct balance between the required properties of whiteness, absorbency etc. in one hand and chemical damage on the other. The traditional process usually consists of chlorination, extraction of the chlorinated lignin by scouring in soda-ash and then bleaching
preferably with alternate chlorite and peroxide stages or even hypochlorite bleach.
Process details of conventional method are shown in table below:
|Kier Boil||Lime||10-12% on o.w.f. 8 hrs at 60 deg C.|
|Cistern scour, Kier Boil||Soda||12.5 gpl, 18 hrs at 60 deg C|
|Cistern Chemic||Available Cl2||1.7 gpl , 2 hrs at pH 4.3|
|Kier Boil||Soda ash||6.5 gpl, 18 hrs at 60 deg C|
|Chemic Bleach||Available Cl2||0.6 gpl Cold Pad Batch overnight|
|Soda Ash||2 gpl|