I’m constantly learning new things about gardening and Alcatraz, even after working in the gardens for close to six years now. On a recent trip to pick up my order for more volunteer shirts, I finally met David, president of Plum, a company in Emeryville that prints our t-shirts and hoodies. David invited me to take a look behind-the-scenes to see the screen printing process.
David has owned the business for 35 years, first starting to print shirts for museums. A connection then led to the Golden Gate National Parks Conservancy, the non-profit organization that manages the bookstores throughout the Golden Gate National Recreation Area. In fact, sweatshirts for Muir Woods had just come off the line. Plum also prints shirts for various humane organizations.
The screen printing is fairly simple
and hasn’t changed that much since the Chinese invented the process hundreds of years ago. Garments are placed on an automatic rotary printer, with each arm having a screen. The first step in the process is to separate each color in the design to exactly abut each adjacent color so that the colors do not actually touch each other; each color segment is printed separately. This step is now done on the computer, but in the early days of the company each color was hand cut. Each color is then shot on its own screen. Setting up the screens so that this can be achieved is a critical part of the screen printing process. The attached screen forms open areas of mesh that transfer ink which can be pressed through the mesh as a sharp-edged image onto the garment. A fill blade or squeegee is moved across the screen stencil, forcing ink into the mesh openings. The garment is then taken off and is placed on a drying conveyor belt. Depending on the types of inks used, the drier is set at 325 Fahrenheit and dries the shirts in one to four minutes.
David estimates that that they can print over two thousand shirts on one machine in one day!
Elliot Michener, our inmate gardener, would surely have been impressed with the setup. Elliot was a skilled printer himself at a newspaper; or perhaps he was not that skilled afterall, as he tried his hand at counterfeiting money but obviously was caught.