Many industries have embraced power washers to improve employee safety and the print industry has also joined the ranks. We know what you're thinking; Print industry? Fabrics? Pressure washers? What gives? For those of you unfamiliar with silk screen printing on fabrics, we'll give you a brief overview on how pressure washers factor in.
Screen Printing — What's Involved?
Screen printing, sometimes referred to as Silk screen printing, has been around a very long time and is a process in which pigments are transferred to fabric in a specific pattern. Many T shirts and fabric designs are created using a process called silk screen printing. Silk screen printing involves different inks being applied to a wide array of substrates ranging from textiles to plastic, wood and metal components.
It's a time consuming, messy process but it delivers the goods. One of the challenges of silk screen printing is cleaning up.
Cleaning Printing Screens
There are a number of components to cleaning up the silk screens — ink needs to be removed, emulsion and haze need to be removed as well and the screen needs to be degreased. Originally, these screens were cleaned by the application of solvents which helped remove inks, haze and emulsions. Haze is caused by pigment left on the screen that bonds with the resin after the solvent evaporates. This work frequently required forceful scrubbing in a washout area which posed a health risk due to skin absorption and inhalation of the cleaning chemicals. These chemicals were typically methyl ethyl ketone, terpenes, mineral spirits, xylene, heptane, toluene, hexane and glycol ethers. Some of these are volatile toxic organic compounds that can pollute the air. Mineral spirits, which contain trace elements of toluene, xylene and benzene is risky as well.
Because of the potential health risks (Hexane has been associated with peripheral neuropathy and ethyl ketone has been found to be associated with the use of cleaning chemicals for silk screens, some screen printing companies have developed a high pressure screen reclamation process which greatly minimized the use of chemicals. Wastewater treatment and chemical exposure were also reduced.
Let's take a look at your options to accomplish the clean up.
Current Screen Printing Cleaning Practice
The Screen printing cleaning process involves four steps: ink cleanup, removal of emulsion or stencil, dehazing and degreasing. Proponents of using pressure washer screen cleaning point to three advantages: Screens are much cleaner due to a more focuses and effective method of cleaning; Less labor and time were involved to clean the screens and substantial money saved by using far less chemicals.
Opponents argue that a pressure greater than 1,500 psi will damage the screen. What one must keep in mind is the condition of a screen before cleaning. It the screen has any flaws, any pressure can cause