Laccase Enzymes
Laccase uses oxygen to oxidise indigo and break it into colourless fragments. It is the alternative to hypochlorite and permanganate bleaching in denim, and because the broken-down indigo cannot redeposit, the back-staining problem goes with it. Two products in the family.
What does laccase do in denim?
Laccase is an oxidoreductase: it uses oxygen to oxidise certain aromatic compounds. In denim the target is indigo. Oxidised indigo breaks into colourless fragments, so the garment fades and moves toward a bleached look.
Denim bleaching has long been done with sodium hypochlorite or potassium permanganate. Both work, and both have a price: hypochlorite oxidises cellulose and costs strength; permanganate brings a separate neutralising step and a heavy effluent load. Laccase works in the same direction and reduces both.
How does it differ from cellulase?
Cellulase abrades the fabric surface and removes indigo mechanically; laccase breaks the indigo down chemically. The results differ, and most recipes use the two together.
|
|
Neutral cellulase |
Laccase |
|---|---|---|
|
Action |
Surface abrasion, indigo removal |
Fading by oxidising indigo |
|
Effect on the fabric |
Weight and strength loss |
No direct action on the fibre |
|
Appearance |
Contrast, abrasion effects |
General lightening, flatter tone |
|
Back-staining |
Stripped indigo is free in the bath |
Broken-down indigo cannot redeposit |
That back-staining difference is what decides it in practice. In a cellulase wash the freed indigo can settle on pocket lining and sewing thread; because laccase destroys the indigo, there is no dye left to settle. For that reason laccase is also run as a clean-up step after a cellulase wash.
Under what conditions does laccase work?
Laccase needs oxygen, so how well the bath is aerated feeds straight into the reaction. A closed machine with little agitation will not give the expected result.
The general working window quoted in the literature for the laccase class is the mildly acid range, and using a mediator raises the effect appreciably. That is a class range, not a product specification. Derin Kimya's figures are given on each product page: pending from the client.
How is the strength of the effect set?
Time and dosage work together, but in denim the appearance decision is taken on a sample. The same recipe leaves a different tone on fabric dyed to a different indigo depth, so when the order fabric changes, the recipe is re-validated.
The enzyme is stopped at the end of the cycle. Otherwise the fading carries on after the garment leaves the machine and produces tone variation within the batch.
Product comparison
Comparison
| Product | Description | Activity | Working pH | Temperature | Dosage |
|---|---|---|---|---|---|
| DK LCC | Laccase enzyme for denim bleaching | awaiting data | awaiting data | awaiting data | awaiting data |
| DK LCC S | Laccase enzyme for denim bleaching | awaiting data | awaiting data | awaiting data | awaiting data |
Products
Common questions
Does laccase cause strength loss?
Laccase does not act on cellulose, so no direct loss is expected. Where the same recipe also contains cellulase, the loss comes from that. Against hypochlorite this is laccase's most concrete advantage.
Can laccase and cellulase share a bath?
The pH and temperature windows of the two enzymes do not always overlap, and an oxidative bath can lower cellulase activity. Common practice is a cellulase wash first, then a laccase step in a fresh bath.
Is neutralisation needed after laccase?
No separate neutralising step is needed as it is with permanganate. The enzyme still has to be stopped and the broken-down indigo rinsed away, otherwise tone variation appears within the batch.
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