What is Pretreatment?

Pretreatment:

Pre-treatment occurs immediately before dying/printing in the textile production chain, and
prepares the fabric for these processes. The fibres may either be in the form of a yarn or a
woven fabric. Pre-treatment normally occurs in the same facility as dying, often in the same
machine (integrated processing = faster processing). A series of mechanical and wet
treatments prepare the fabric in a variety of ways:

􀂃 Removal of foreign material from the fabric.

Natural impurities present in wool and cotton, production residues in manmade fibres

and previously applied processing auxiliaries must be removed. This improves:

uniformity, hydrophilicity and fibre affinity for dye stuffs and finishing auxiliaries.

􀂃 Improving the ability to absorb dyes uniformly.

In the case of cotton a chemical treatment is applied (mercerising) to alter cellulose

crystallinity.

􀂃 Relax tensions

Synthetic fibres are often subjected to a heat treatment relaxing tensions due to

upstream processing (Lacasse, Baumann 2004).

􀂃 Bleaching

To allow light dye shades or to produce white fabrics.


The nature and number of pre-treatment stages depends upon both the fibre and the required
end result. Natural fibres generally contain more impurities and so are subjected to more
intense processes.

The type of environmental pollution resulting from pre-treatment depends upon process
ordering; if heat processing precedes wet then the off gas contains a higher proportion of the
removed impurities and vice versa.