Cotton Textile History--printing, dyeing, manufacturing and trading.
Sunday, October 3, 2010
Resist vs Discharge
There are 2 ways to 'print' indigo. The earliest approach is to print a resist on the undyed cloth. The resist can be mechanical--flour, starch, clay, resin, or wax--or chemical--salts of copper, alum or zinc. The length of fabric is then processed in an indigo dye bath. The pattern printed resists the indigo dye. A rinse of warm weak sulfuric acid removes the wax or zinc salts and you have an off white design on an indigo ground. Wonderful!
Early in the 19th century a second approach was developed--the discharge method. The fabric is first dyed indigo blue and then a discharge paste is printed on that fabric. The oxalic acid 'bleaches' out the pattern design. The look on the printed indigos is similar. I have had people tell me they could tell the difference. Alas, I was not able until recently. In March I purchased some quilt blocks from a Senior Citizen's Center in eastern Ohio. There was one group of 8-pointed stars dated c. 1825 which had several indigo prints. The back of one was different from the others. I think you can see how deep blue the back of this indigo piece is.
There were pieces in other blocks whose backs look like this. You can see a 'shadow' of the design on the back. I think now if I can see the back, I might be able to detect Resist vs Discharge.
I thought you would want the see the fronts of these two blocks!