From: Marcia Kinter (firstname.lastname@example.org)
Date: Thu, 28 Feb 2002 12:16:39
Hope this helps. This response came from a representative of a textile ink manufacturer.
Discharge printing is also a screen printing process. The "inks" used are different. There are several process which are referred to as discharge and they are all quite similar, the main difference being the method and time necessary to extract the dye. The process is quite common and has been used for many years. Discharge printing is the process used to print patterns in some types of carpeting and is also used in the manufacture of the felt cloths used on gambling tables.
As you may have guessed by now, discharge printing "extracts" the dye present in the fabric and replaces it with the dye in the ink. The value of this process is that it gives the softest hand possible to the fabric after printing. Printers use it on dark fabrics to give them a hand similar to that possible on light fabrics with regular inks. After printing, the fabric is placed into or runs through a drying chamber where the old dye "steams" out and is replaced. It is a water based ink system that utilizes an active ingredient called zinc formaldehyde sufloxolate. It sounds worse than it is and its residue is usually removed after the process by rinsing and drying the fabric one more time. The key thing for you as a buyer is to make sure that your supplier is doing this post printing rinse to remove the ZFS residue.