The Perfect Laughter Guide to Screen Printing Problems

posted by christina

Learning to screen print can really pay off, but it’s pretty intimidating to try it. There are so many ways something can go wrong, it’s really difficult for rookies to get decent results. It’s no wonder than many people who like the screen printed aesthetic go the Gocco route.  But with supplies getting scarcer and more expensive, it’s worth it to learn regular old screen printing.

As you can see from these photos, we don’t have any fancy equipment. We’ve never bought any kind of beginner “kit”, only screens, emulsion, and transparencies from Kinkos. Our screen is sitting on a black t-shirt and our hardware store light is supported by a board, a washing machine and a ladder.  Our “press” is just a large board with some hinges screwed to it. The real investment we made is was the time we spent getting it to work!

We wrote this guide to help people avoid some of the frustration that we experienced when we screen printed our wedding invitations. It’s not a beginner’s guide – it assumes that you’ve researched the basic process, tried it yourself and need help troubleshooting. (If you’re a beginner, the Gigposter forums are a great place to start.)

Our complete guide is behind the cut. We hope we can improve it over time, so please comment with any suggestions!

After exposing, the emulsion won’t wash out where it’s supposed to. Parts of the design didn’t burn.

Make sure your positive is opaque enough. We use two transparencies taped together. They must match each other exactly. Double-sided tape is your best friend for this part.

EDIT: We’ve ’sperimented with using only one transparency. One seems to work fine when we use a fast exposing emulsion (< 10 minutes). Two is usually needed if your exposure time is longer.

Also, make sure your screen has been drying in the dark before you expose it. You’d think this was a no-brainer, but we fell victims to a closet door that was letting a sliver of light through.

After exposing, my emulsion is washing out where it’s not supposed to. I’m losing fine detail.

If you’ve used the screen before, you have to use a degreaser before coating it with emulsion. No fancy chemicals are needed, just wash your screen with dish soap after removing any old emulsion. Otherwise, a film will form on the screen and the new emulsion won’t adhere well.

If that’s not the problem, make sure your positive is being held down completely flush to the screen. We had been using a clear piece of plastic or plexiglass, but it wasn’t heavy enough. Thrift store picture frames are cheap sources for big pieces of glass.

My screen is burning fine in the middle, but the emulsion is washing out around the edges.

Your light is coming down from its source in a cone shape. If the light is too close to your screen, the entire design won’t be inside the cone of light. Move your light source away from your screen. You may need to lengthen your exposure time after you do this.

My prints are faint and/or there are some spots where the ink isn’t pushing through onto the paper. (This is where we had the most trouble. Alternative solutions welcome!)

EDIT: We just found out that spraying water on the underside of the screen before you put any ink on it helps a lot!

For some reason, our screens were getting clogged in certain spots. This mostly happened at the beginning of each run. We rubbed the trouble spots on the underside of the screen (closest to the paper) with a wet cloth. We used a lot of pressure when we did this, and it cleared out.

Because we were having this problem, we did a LOT of test prints on scrap paper before beginning to print on the good stuff.  After about 5-10 test prints, sometimes more, the ink was flowing through the screen pretty well and we had identified and fixed our trouble spots. But this process was pretty frustrating and took up a lot of time.

More advice: work fast once you start printing. If a screen full of ink is left idle, the ink will start to dry inside of the holes. If you do have to stop for a minute, flood it to provide a “blanket” of ink to protect the holes from air. Also, make sure your inks are closed tightly in storage so they don’t thicken.

My prints aren’t sharp. It looks like too much ink is getting globbed on the paper.

At first, I thought I was holding the squeegee wrong or applying the wrong amount of pressure. However, it actually has to do with the amount of ink that’s already sitting in the holes of the screen. After pulling a few prints, especially if you flood it after every one, excess ink may begin to collect on the underside of the screen. The only way we could fix it was by wiping off the screen (the side closest to the paper) with a damp cloth. After each print, make sure the ink isn’t going on too heavy, and if it is, pull a few prints without doing a flood stroke.

I can’t reclaim my screen after printing. The emulsion won’t wash out.

Assuming you don’t have a dark room with a fancy drying unit, how long did you let the emulsion dry after you coated the screen? If you exposed a screen without letting it dry completely, the emulsion could have fused to the screen. Cue sad trombones; it’s never coming out. Next time wait at least 24 hours before exposing, or more if the weather is hot or humid.