Screen Printing Guide

Screen printing is so dang hard, and so many things can go wrong in any given moment. I had to learn a bunch of this stuff the hard way, so I'm writing it down for others.

Equipment

Here's what I recommend for screen printing. All of these items will be explained in the guide. I found most of this stuff in a $100 screen printing starter bundle at Blicks. It came with a screen, photo emulsion + sensitizer, squeegee, UV lamp, transparent paper, and some inks!

Screen pre-prep

If you got cheap screen like me, then you'll find a groove on the back (for this guide, when I refer to 'screen' that also includes the frame). This groove holds a plastic tube guy that keeps the screen in place. If you pull the tube out (don't), then the screen comes off. What you need to do first is seal this groove. Why? Because photo emulsion (what we'll be coating the screen with) hardens after UV light exposure. If any photo emulsion gets over that groove (and it probably will), then gets hardened by UV rays, it'll be a huge pain to try to take out the screen. Replacing the screen is a last resort option when things go wrong, and if things go wrong, then you'll want that part to be easy.

Seal the groove with some duct tape.

Don't have the tape go over the exposed mesh area, have the edge sit right where the frame ends going into the mesh, then fold the tape over the other side. That way, you're not reducing the print area.

Coating the screen

Preparing the photo emulsion

Photo emulsion is a liquid that gets hardened by the UV rays in your UV lamp (also by the sun!). Cheaper emulsions will come with a tiny bottle of sensitizer. This section is all about the sensitizer.

Mixing the sensitizer

Speedball photo emulsion is light blue, the sensitizer is a yellow powder. Once mixed all together it becomes a nice green. Without the sensitizer, the emulsion doesn't harden, so make sure it's green. The instructions say to add water to the sensitizer bottle (3/4 the bottle), shake, then add to the emulsion. There's more to it than that. The powder will stick to the bottle!

Fill the sensitizer bottle 3/4 up with warm/hot water, shake, then use a toothpick or something to scrape the bottom. Shake it a whole lot, then add it to your emulsion and stir.

coating the screen

Print shops will have a special screen coating scooper tool thingy, but I don't. I'll explain how to coat the screen with a squeegee. Make sure your squeegee is an appropriate size. It shouldn't be a couple inches shorter than the shortest inner side of your screen. That way you have some wiggle room, but you can also cover your whole design in one swipe. When we coat the screen, don't think about getting a thick coat, try to focus on getting a thin coat, but don't press crazy hard when swiping. If the coat is too thick, then it will dry with bubble pools and be annoying.

Put a bead of photo emulsion along one end of the screen, swipe the emulsion a couple times to try and cover the whole screen. As you swipe, the emulsion will go through the screen, so flip it over ever couple swipes. Make sure to cover every inch of the screen, adding more emulsion as needed. Once it's all covered, swipe over each side a couple times and drain the excess emulsion back into the container. This will make sure the coat isn't too thick.

It takes about 4 hours for the emulsion to dry. Once it's dry, it'll feel hardened, but will wash away with water, warm water especially. Putting a fan on the screen will decrease the dry time to about 1 hour.

Once Dried

Congrats! Your screen is all ready to be burned yo. First we gotta prepare the artwork and transparent sheet.

Preparing the artwork

The art itself

From here on the guide isn't finished just yet. I just be putting down notes to remember

When you create the art digitally, it must end up 100% black and white, NO GRAY. Either ink goes through the screen, or it doesn't. The only way to get some sort of halftone or gradient effect is to use dots. Even then it will be very difficult to burn. I usually print art onto a transparent standard 8.5" x 11" paper.

Printing the transparent

Make sure you got an ink jet printer. Your printer is either laser, or ink jet. Even ink tanks feed into an ink jet head, so those are good too.

Transparent sheets are only printable on one side. Lick your finger then touch a corner of the paper. The sticky side is the printable side.

Also be sure to know if your printer prints onto the bottom of the paper or the top. One of mine prints on the bottom! If you print on the wrong side of the transparent sheet, then your ink will smudge and spread like crazy.

Burning the screen

Hang the UV light around 16" inches above where the screen will be placed. Place the transparent on the screen, it better be the correct orientation. Normal looking on the front, but flipped if placed on the back. The transparent can be placed on either side, and I usually do the back so I can lay a coffee table glass piece on it. That way, the transparent is completely flush with the surface. Make sure the piece of glass can cover the entire piece of art!

correctly pin the transparent between the screen and a sheet of glass or something similar. If you can't, then tape it down. Turn on the UV lamp for your desired amount of time.

UV light times will vary. I do 9-1/2 minutes for mine. You may need to do muliltiple tests. When testing, change burn time at 30 second intervals.

Washing the screen

Washing the screen is often overlooked in screen printing guides. They say 'Just wash it out', but it's not that easy. Most screen printing shops utilize pressure washers to blast their screens clean in a matter of minutes. I just got a kitchen sink. The best tip I've found is to soak the screen first, then spray on your strongest cold setting. Hot water will wash out even the cooked emulsion.

Only utilizing cold water, soak the screen for a few minutes then blast it with the most pressure you got

Congrats! Your screen is all ready to print

Printing

note: spray a mist over the screen between prints, otherwise the ink may harden within the mesh and prevent printing in finer details.

Reclaiming a screen

so you're all done with a screen and want to put a new design on it!

Using emulsion remover

Emulsion remover is a double edged sword. It needs to soak a minute or two before washing, but if it dries, then the emulsion becomes PERMANENT!!!