[Grnr12]

Hi all, I'm new to the forums.
Been trying to make some screens for the past week but every time I go to wash off the emulsion my whole screen washes off.
I'm using Ulano FX-88 Diazo direct emulsion, I am using a light table, 3 fluoro hoods w/ 2 48' 40 watt bulbs in each hood. I have tried exposure times ranging from 50 mins all the way to 80. Does anyone see anything wrong with what I am doing? Any help would be greatly appreciated.

 

[darwinchristian]

did you mix the diazo sensitizer into the emulsion before coating the screen?

 

[Grnr12]

Oh but of course. Followed the instructions on the bottle, stirred it completely together, allowed the air bubbles to settle out. I don't have a coating trough, but I manged to spread the emulsion evenly across the screen w/ my paddle. I have been using cold water to rinse the emulsion off w/ one of those hose attachments to get some pressure, but I am no spraying the crap out of the screen, once I start to get some of the non-exposed emulsion off, it seems the rest just follows. And when I take my screens off the light table, I can see the words/design in a lighter color.
Are there any things you do before applying you emulsions to your screen?

 

[darwinchristian]

well, since the emulsion has been sensitized my only guess is that you are under-exposing.

perhaps your neon bulbs are filtered uv bulbs. you need to be sure you are using non-filtered bulbs with non-filtered glass. it's a "uv type a" light that reacts with the sensitizer.

search the forums for exposure calculator. this is a good place to start.

basically, increase your exposure time and decrease light distance until you achieve results. if things stop washing out altogether, you may be overexposing...

hope this helps.

derek

 

[Grnr12]

alright, thanks so much derek, this will get me going in the right direction, I think I may need to get different bulbs. Any special suppliers of these? Or can they be found at a hardware store/megamart?

Alex

 

[darwinchristian]

i just looked at the ones that came with my exposure unit. they say "UVA lamp, avoid exposure to skin and eyes."

i'd call the hardware store first. if they can't get it, they'd likely be able to tell you where to go.

 

[out da box]

You may be over-exposing. 30 minutes sounds like an eternity. Try an exposure calculator. Or try exposing for a much shorter time and see if anything washes out.

 

[cmyk]

i am no expert, but do you properly degrease the screens before coating with emulsion?

 

[INKFREAK]

There are a couple of things.You need a proper coater to get a uniform coat of emulsion .Thick areas just will not expose and wash out.You will see the unexposed shadow but as you rinse the thick parts will absorb water and soften up and fall off with the image.degreasing is also another culprit.Are you using dish soap?or a proper degreaser?No insult intended,some people do.And the flou. bulbs your using do not sound like they are giving you the intensity you need.Call a lighting shop and ask what will fit you table that will give you more omph.

 

[darwinchristian]

You may be over-exposing. 30 minutes sounds like an eternity.

on second thought, i agree with Ridgely.

if you aren't seeing the image wash out slightly before the rest of the screen, after seeing a lighter image in the screen after exposure, than you are probably over-exposed.

how fast does the emulsion wash out with a garden hose after exposure?

 

[spankthafunk]

Wouldn't overexposing cause the screen not to wash out at all? I thought that if you are overexposing, you are completely hardening the emulsion to the screen.

 

[out da box]

Yeah he did say "totally washes out". Maybe bad emulsion-sat too long. Maybe too much humidity. Maybe screens not properly degreased.
Don't see under-exposure being the problem. I used to use fx88, took 1 minute in the sun, 10 minutes with flourecent tubes, 1 minute with metal-halide.

 

[spankthafunk]

I'm putting my money on the bulbs or degreasing the screens, probaly the bulbs. For 50-80 minutes there should have been somethin happening. Try doing a test by putting some emulsion on the screen and just sticking it out in the sun for 30 minutes. If it hardens, than it's one of the two problems mentioned.

 

[INKFREAK]

Maybe too much time.But you can always wash out a screen thats properly exposed with a garden hose and nozzle.You're over exposing if you have to use a powerwasher to get the scum out.