Slashtee The Process

The Process

Ever wondered how silkscreening works? I did too. It’s a complicated process that ultimately provides you with a never changing stencil with which to do your prints. However it takes a bit to get there.

First we start with a screen. A screen is made of a piece of porous, finely woven fabric called mesh stretched over a frame of aluminum or wood. You can get different sized mesh, from course (low res) to fine (high res) mesh. I use a size in between, technically it is 140xx mesh.

A screen.

Next we must make our screen into a stencil. We do this by coating the screen in a photosensitive solution called emulsion in a dark room. When exposed to light, emulsion closes up the mesh wherever it covers the screen, wherever it isn’t exposed to light it doesn’t cover the screen and the mesh will still be “open and ink can still flow through it.

Exposing the screen

After exposing the screen: the paper you see underneath the screenis vellum with the design. In the screen you can see the dark areas where the emulsion closed up and the light areas where it can be washed out.

So using what we know about emulsion we can use a piece of vellum to block the light from hitting our screen in exactly the shape of our design. By printing the design in black we block the light to the screen. By placing the screen in a huge light box, we can control how the emulsion gets exposed to light. When it is done the areas that were exposed to light are now bonded to the screen and the areas that werent exposed wash right out of the screen leaving the mesh open. We now have our stencil! The next step is sealing off the open areas of the screen that didn’t get covered in emulsion or fixing any holes in the screen where for any reason the emulsion didn’t cover.

Registration

Time for preparation. At this stage we mix our inks to the desired color and prepare our print station with the squeegee. After securing our screen in place (although it it may get moved during the next step), one of the most important step takes place now; registration. If you want your print to look the same every time and line up with any layers you make have, you must be able to predict where the image will fall on whatever you are printing. When printing on paper you can use special registration clips to line up paper in the same place every time. These marks go on two sides of the paper so that it can be slid out easily and new paper can be slid in and still maintain the same right angle. For printing on shirts it’s a bit more hit or miss. Using my large press I must first line up all the screens with each other as close as possible to the center of the platen (my printing surface). Then I must see how I have to align the shirt on the platen to get the desired location. To stop the shirts from moving around while I’m printing, I use spray adhesive. But once I take one shirt off, I really have to almost eyeball the next one. I use some crude measuring, but it’s very hard to be perfect.

This shirt was registered and printed almost perfectly in-line

Now we can print! Taking the squeegee, lift the screen and put ink on the screen in the area closest to you. Then flood (fill) the screen by running the squeegee with a little pressure over the screen away from you. This forces some ink through the mesh. Now lower the screen onto the printing surface and make a strong pull towards you. Lift the screen and admire the print. At this point we can print almost indefinitely if we have enough ink. But if we want to try a different color all we have to do is wash out the screen of the old ink in a slop sink. The emulsion will stay in the screen and we can start on the next color. Eventually when we want to reclaim the screen a special chemical is used to break up the emulsion and the screen become as good as new ready for more prints.