Anti-Peroxide (Catalase) Enzymes

The hydrogen peroxide left in the bath and on the cloth after bleaching oxidises the dye and shifts the shade once it reaches a reactive dyeing. Catalase splits that residue into water and oxygen. Derin Kimya's anti-peroxide family holds five products.

Why is residual peroxide a problem?

When a peroxide bleach finishes, some peroxide is left in the bath and on the cloth. Carry that residue into a reactive dyeing and it oxidises the dye: the shade comes out weak, it drifts, and reproducibility is gone. The awkward part is that the residue is invisible and the fault only surfaces once the dyeing is finished.

Catalase splits the remaining peroxide into water and oxygen. The reaction is fast and leaves nothing behind that affects the dyeing; the oxygen released leaves the bath as gas.

Why not just rinse, or use a reducing agent?

Both work, but the three routes cost differently.

The real gain with catalase is water and time: because the peroxide can be destroyed without dropping the bleach bath, the number of rinses falls. With a reducing agent, any excess carries straight into the dyeing, since what stays in the bath will also act on the reactive dye.

Where and when is catalase dosed?

Two routes are used. The first is a separate short bath after the bleach liquor has been drained: the medium is clean and the enzyme works comfortably. The second is dosing straight onto the bleach liquor once temperature and pH have been brought down, which is where the water and time saving is largest.

In mills taking the second route, the alkali, stabiliser and stripped soil left in the bath put the enzyme under strain. Broad-window grades are preferred under those conditions.

How is completion confirmed?

With peroxide test strips. A sample is taken from the bath, touched to the strip and matched against the colour scale; the treatment continues until the peroxide is gone. Taking that reading before the dyebath is made up is one of the cheapest checks in a dyehouse and prevents a large share of dyeing faults.

The reading should be taken from a squeezed fabric sample as well as from the bath. The liquor can read clean while peroxide is still inside the cloth.

When does catalase fail to work?

The working window quoted in the literature for the catalase class is generally near-neutral pH at moderate temperature. That is a class range, not a product specification: pending from the client.

Two mistakes are common in practice. The first is dosing catalase before the alkali from the bleach bath has been neutralised; activity falls at high pH. The second is the stabiliser and heavy metal load still in the bath. Wide-window types are formulated to loosen both constraints.

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