Screen Printing Forum

Hello

Firstly please forgive me for my stupidity as I am very new to screen printing!!
I recently bought some equipment with the hope of making some beautiful prints, however I'm having a few teething problems and I cant remember what I'm doing wrong...

1. When I apply the photo emulsion it doesn't seem to want to take to the whole of the screen and is very patchy. I eventually managed to cover it but when holding it up to the light, it didnt look very even.

2. When it came to the actual printing, i had the same problem with the ink. I am using textile inks, could it be that they are too thick or something?

3. Also, the print was a mess! Not only was it patchy where the ink wouldnt take to the screen, but it also looked like i'd applied it with a sponge. The paper that I was testing on would also stick to the frame. Do I need more clearence between them?

I would be so grateful if anyone could give me any tips on these problems because I am making a complete mess of it and I really would like it to work!

Many thanks and apologies for asking silly questions

1. When I apply the photo emulsion it doesn't seem to want to take to the whole of the screen and is very patchy. I eventually managed to cover it but when holding it up to the light, it didnt look very even.

Sounds to me like you did not prep your screen properly. If it is a brand new screen, you need a mesh abrader. You can get this from your local screen supplier. If it is a used screen, then you need to have a degreaser. Alot of dehazers have degreaser in them. Get the screen wet, add the degreaser and apply on both sides with a brush. Let it dry. Most importantly, do not touch the mesh. Any grease from your hands will mess up the prep and you have to do it again. After it's dry, then you can apply your emulsion. This should get rid of the problem of patchiness.

2. When it came to the actual printing, i had the same problem with the ink. I am using textile inks, could it be that they are too thick or something?

I'm not sure what you mean by having the same problem. If you mean the ink would not push through properly, it could be that you underexposed the screen. When you let it dry, the water may have ran across the image and even though it looked like it was washed out, there was a film on it not allowing it to push through. Another problem may be your film positive is not dense enough. Too much light may have shown through the black image and it may not have let you wash the image out enough. There are many factors in this, and really can be solved by a step by step process in screen making.

3. Also, the print was a mess! Not only was it patchy where the ink wouldnt take to the screen, but it also looked like i'd applied it with a sponge. The paper that I was testing on would also stick to the frame. Do I need more clearence between them?

It may have stuck to the frame because you didn't apply any screen tack to the platen. If that's the case, then the paper will definitely stick to the bottom of the frame. I usually don't test on paper, but on a used shirt or cotton material. As for applying like a sponge, again, look at what I wrote above for the possible cause.

Basically, you want a nice dark, dense image for your film positive. This will let no light shine through. If this is the case, you can expose your screen for longer periods of time. Without a step wedge, one way you can do it is add a couple of minutes to your exposure time. When you wash it out, if your image was dense, it should wash out well but not leave any residue. If this is the case, you can start shaving time off of each exposure, maybe 30 seconds at a time. If you go back too far, then add 15 seconds, etc. until you find the right exposure time for your setup. Another way to help is when you are drying your screen after it's exposed, lay it flat. Some people will take a large paper towel or even a newspaper and lay it flat on the screen. It will suck up the extra water on the screen, not letting it collect in the image area. But again, if you properly expose your screen, you won't have to worry about this.

Hope this helps and good luck.

Thank you so much for taking the time to write such a helpful reply.
Last night we managed to do some really good prints so we're really pleased.
Thanks so much for your help!!

One note on coating the screen with emulsion...

I recently learned that it may, in-fact, be better to coat screens with the round edge of the scoop coater instead of the sharp edge. I had always been taught the opposite of that.

The reason for the round edge is that it lays down a thicker layer of emulsion thus allowing for a more level stensil on the print side. With todays emulsions, a thicker stensil will help ensure nice, sharp lines and edges.

Any thoughts?