Shade matching in stone washing is a very critical technique. Stone washing is a batch process and unlike continues process operation it is centralized to each batch separately. During enzyming and bleaching processes, shade control is done manually to keep the shade consistency in bulk productions.
Special nature of denim fabric compels different shades within the fabric and to a marginal variation it is present in all types of denim fabrics. As a result different garment from same fabric lot will result to different shades although they are processed in same conditions with same chemical recipes. This shade variation is minimized by controlling chemical quantities, temperature, time and other parameters during process.
Shade Matching in Enzyme / Stone Process
Enzymes and pumic stones are responsible to create paneling effects and white grains on garment. In modern techniques it is usually done with enzyme alone but some time addition of pumic stone helps to increase the extent of effect. Quantity of chemical is recommended by manufacturer in respect to liquor ratio.
For best results, minimum quantity of chemical is used for maximum time. This will produce intense effect without disturbing the shade of the garment. Enzymes used for this purpose can be classified in four major categories as
a)Hot Bath Enzyme
b)Cold Bath Enzyme
c) Acid Enzyme
d) Neutral Enzyme
Hot bath enzymes are more rapid in action but back staining is a major issue to this kind of enzyming. This high temperature also create some complications in measurement so is not recommended to high quality washing. Due to less process time it is most commonly used in industry. In improved versions of enzymes these enzymes are additionally equipped with anti back staining properties
Some time additional quantity of enzyme is used for increasing effect or some time to reduce the run time of batch but this will tend to shift the shade to bluish side. Reason stands for that, that more enzyme will remove more indigo form fabric and back staining will increase. Also the higher quantity of chemical tends to reduce shade more rapidly without making much effect on panels. Additional quantity will only help where high production is required in less of the time but shade quality is compromise able. Best way to get good results is to add some pumic stone and specially where a grayish look is required. In enzyme shade matching some key points are as follow.
- Higher quantity of enzyme will increase the back staining and in blue fabric will result to merged bluish shade, this problem can be overcome by adding additional ABS (Anti back staining agents).
- Enzyming in less water bath increases the enzyming action but again favors to back staining.
- Low quantity and greater run time will result to more clean and defined graining effect, also will keep the tone to grayish side.
- Adding pumic stone will help to increase the effect of enzyme in lesser time. It will also help to keep the shade neat and more raw.
- When graining and paneling effect is required without disturbing the shade then pumic stone without enzyme is best solution.