[Kee440]

Hey there, hopefully you guys can help me.

I've tried searching for help but can't find anything specific to my problem.

I'm trying my very first screenprint and I have a very minimal, DIY setup (I'm a student with very little money).

The screen I'm using is a 120T (around 300 US count) screen. And the emulsion is the Speedball Diazo kit.

My problem lies in the exposing of the screen, the lamp I'm using is a 400w halogen worklight. I've tried 3 times to expose the screen and each time it only leaves a faint trace of the design. Washing it does nothing (I'm only using a shower-head but it's fairly strong).

I've tried various intervals of time, first was 15mins, then I tried 30mins and then I left it way over an hour. Everytime there wasn't much difference in the appearance of the screen.

The 3rd time I tried removing the protective glass shield on the halogen lamp as I read that was protecting UV? But that made no difference.

I was starting to think that it was something to do with the glass holding down the design, as that seems fairly reflective but surely not?

This is the design I'm trying - [media]http://f.cl.ly/items/1L1F2i3P0J0q0G453h1b/aztek.jpg[/media]

Any help is appreciated!

 

[ScreenFoo]

You have a lot of detail in the image--how are you keeping the positive pressed against the stencil/dried emulsion?

You may want to try less time, as well--it's difficult to get a lot of detail without underexposing, especially with a diazo, on a low wattage halogen.
Someone will soon tell you that anything speedball is junk, and that you should throw it away and buy whatever brand they think is great, but assuming you followed mixing and storage directions, and expose it properly, it should work--just to give you a heads-up.

 

[Kee440]

Yeah the image is pretty detailed, I might try a simpler design as a test to see if that works. I'm using just some glass I got out of a picture frame to hold it down.

Haha yeah, I think I followed the instructions correctly so I don't think it's speedball's fault!

I'll try exposing it for less time.

Out of curiosity, what would the screen look like if I had overexposed it? The design I can see faintly on the screen is a little darker than the emulsion.

 

[ScreenFoo]

If you overexpose, the details tend to close in--and you can't wash it out.

Of course, the other thing that makes this difficult, is that if you're coating differently, a thicker stencil may be underexposed at 15 minutes, while a thinner one will be overexposed at 15 minutes. Try to keep everything consistent and change one variable at a time.

If you expose the same coating on the same screen at the same distance, etc., for 10 minutes, and the whole stencil washes out, then you'd want to look at either your positive to stencil contact, or how opaque your positive is. You can try sticking a piece of electrical tape on a corner away from the design to test that as well--if the tape square washes out, and nothing else does, you may want to look into a different option for positives.

 

[Kee440]

Ok cool, I'll try that too.

I'm pretty consistent with the thickness of the emulsion, so I don't think it's that.

 

[ai file]

kieran, try aiming for underexposure and work your way up from there. 15 minutes seems pretty long - try 5 minutes and see what happens. Good luck!

 

[Kee440]

Ok so I tried a shorter exposure time of 10mins, and I had a bit of a better result.

I could see the design on the screen, this time it was lighter and part of it washed out with a bit of scrubbing (although not completely).

The piece of tape I stuck on exposed a lot better, that washed out straight away. So I'm assuming it has something to do with my positive? What could I do to make it better? It's only an inkjet print on acetate but it definitely looks dark enough.

Here's a pic, sorry for the terrible quality
[media]http://i.imgur.com/CjPij.jpg[/media]

 

[sben763]

Reduce your exposure time. With detail and halftones you need to be at or under you optimal exposure time. 5-7 min may get you closer with your set up. wet down screen let sit for 1-3 min then wash out. If you scrub on a slightly under exposed sceen you can remove the stencil easily. Post a pic of your film.

 

[Kee440]

Okay Ill try 5 minutes next, and I'll report back.

This is my film: [media]http://i.imgur.com/t5xve.jpg[/media]

 

[sben763]

Your film looks good for most part. It looks like there maybe some grayscale int the film but could be the pic as I see glare on it.

 

[superD70]

You also need a bigger screen or a smaller design, that is too close to the frame to get a good even print

 

[Kee440]

Okay 5 minutes seems to have worked! It washed out fine and it looks good. I haven't done a test print yet but it seems like it was a success!

Thanks to everyone who helped!

 

[Kee440]

Hey, to save making a new thread I'll just ask here.

I've cleaned my screen and the ink is kind of trapped in the screen, I can see the complete design still. How would I clean it out?

I've searched and read about screen wash? And a pressure washer, but at the moment I can't afford a pressure washer. Where abouts could I buy the screen wash?

Cheers

 

[PhilR]

Hey, to save making a new thread I'll just ask here.

I've cleaned my screen and the ink is kind of trapped in the screen, I can see the complete design still. How would I clean it out?

I've searched and read about screen wash? And a pressure washer, but at the moment I can't afford a pressure washer. Where abouts could I buy the screen wash?

Cheers

It's very common for ink to stain the mesh, it doesn't cause any problems unless there is ink actually blocking the mesh openings. Or the image haze becomes so dense it interferes with registration.

 

[InkedApparel]

do yourself a favor and get a exposure calculator..its called a stouffers 21 step wedge test and get some haze remover....check your local supply store.

Inked