For the Christmas season with Molly Crabapple, we designed a number of two-colour apparel prints.. Unlike poster printing, two or more colour t-shirt printing requires a bit more precision.
Since you’re using a silkscreen press, the screens need to be the same size, because your images need to be measured to the exact same place on both. This is because your t-shirt must remain in the same position, as the screens rotate and print on it in the same round.
Firstly, make sure that your separations line up. When printing them, they must be printed in the same direction. If one layer lies vertical on the page, and the other lies horizontal, minor stretching in the film as it prints can cause a distortion. So always check your separations before burning your screens!
If you didn’t put registration marks in your separation, make sure to draw some.
Into the dark room!
Firstly, place them as close to center horizontally as possible. Then it’s usually better to align vertically a little bit closer to the top. You want enough space to pull the squeegee to the end, but with the understanding that the platen needs to fit under the screen.
Measure to the registration marks to ensure that both images are centered and in the same place on the screen. This is why it’s best to use two identical sized screens, so you’re not doing some kind of wibbly math figuring out the correct placement on each size.
And then there were two!
You won’t be able to see how they place on top of each other, but when you press face to face, you can see where the tops and edges line up.
Once your screens are set, place the t-shirt on the platen along with the separation. Measure to the registration marks.
On both, to make sure it’s correct. Assuming your t-shirt isn’t black, it should be easy to read the separations through the screen. If you’re working on a black tshirt, you can slip a white piece of paper between the t-shirt and the separation in order to view it better.
Insert into the press.
The reason it is most important to make them the same size is because with a press, you can move it side to side, but it can’t slide up and down. So it’s imperative that you make sure they are as close as possible. You can be off by an 1/8″, and adjust by placing cardboard or thin pieces of wood between the screen and the platen clamp to adjust the angle. But you can’t put too much wood, or else it won’t clamp down and will wobble as you lift up and down, messing up your registration.
White ink is a very thick ink. It’s usually best to use a fairly open mesh. But if you need to maintain tight details, you’ll then start to have trouble pushing the ink through the screen to get full coverage. This is a print with one pass in white ink (on a sample black t-shirt).
You can then use a hair dryer to dry the top layer of the ink, then place the screen down and do a secondary pass of white ink. This should put down a thick enough layer for opaque coverage. You’ll need to be careful not to overprint a halftone – usually for those, you’ll only want to do one pass. Sometimes in images that are have both open prints and tight halftone prints, you could put them on two separate screens for better control. Or just be very careful when doing two passes.
Especially, make sure to keep a lot of spray tack on the platen.
As you print wet-on-wet in this manner, some ink may stick to the screen. This can also lead to the t-shirt sticking slightly to the screen. So it’s important to make sure your platen is tacky enough to hold the shirt on. If it shifts at all, it can mess up your registration or cause double printing on a two-pass white layer.
A beautiful and professional two-colour print. The t-shirts used were Anvil’s fashion t-shirts in “Lake” colour.
Rock that awesome t-shirt you printed.