Issues Burning Screen with 500 Watt Halogens

[Charmaine]

Hi, I am trying to figure out what is wrong, I am trying to burn an image using a new unit that I made. For some reason the emulsion doesn't appear to be curing, it is not getting hard at all (it washes out really easily when I start over--making me think its not curing at all) and the image doesn't even appear in slight on the screen when I wash it out to start over


The unit I made is out of an old table (the lamps sit about 20 inches from the glass)

---The unit has Annealed glass (which I'm not sure if I can use this type of glass? its different from tempered glass--I think it is a type of float glass---but I'm not sure if it is the problem)--the glass is pretty thick 3/4 inch but it is not solid there is a gap in between it--so its essentially two pieces of thin Annealed glass glued together (1/4 inch each) with a void in the middle
--I am also trying to burn the image using 2 500 Watt Halogens, I took the cages and the tempered glass off the lamps
--I'm using Ulano QTX on 230 mesh with a transparency I made--I have used this emulsion before and with the same type of transparencies at school and it worked fine
- Even after 30 minutes the image does not appear to be burning into the screen --I'm coating the screens in a relatively dark area, in my garage--and I cover them with black cloth during the day-- I also use the same cloth to over the back of my screen and weight the cloth down on all sides to trap in the light when I expose-


- I tried burning the screens last night with no glass only the lamps, and it still did not burn which makes me think it is possibly the lights...

any advice, I need some help =)

[Charmaine]

I coat my screens with just 1:1 application on each side with a scoop coater, I set them up in a dark area and place a fan closeby to let them dry overnight

[ApeShirt]

From what I'm gathering it sounds like a couple different issues. First, you have to ensure that you are coating, drying, exposing, and washing out in a light safe environment. Being in a garage and a piece of black cloth doesn't sound like that's the case. You could be unintentionally exposing your screen. Also, I'm just speculating again but the glass might be wrong. You want a thin sheet of clear glass. A thick piece or "double pane" may be diffusing your uv rays. Now assuming those aren't the issue then you just may need to increase your exposure time. Also, disperse some weight on the film when exposing as that may help get nice contact with the glass. Good luck and keep us informed.

[Saati]

- I tried burning the screens last night with no glass only the lamps, and it still did not burn which makes me think it is possibly the lights...

any advice, I need some help =)

When you say it still doesnt burn do you mean the entire screen washes out clean as if no emulsion was hardened?

[Charmaine]

The emulsion isn't' hardening at all---the entire screen washes out super easy, even after trying to expose it for 30 minutes under 2 500watt Halogens

[Saati]

Yes something is very wrong. The QTX is a fast Photopylmer. 30 min under any light should shold show some signs of exposure. I would first want to find out whats up with the emulsion before we work on the light source. And I agree that the double window is not doing you any favors. All exposure glass should be optically clear float plate glass. You must have no coatings on this glass at all. It will interfear with the exposure.

· Plate glass
· ¼” thick
· Swiped / polished edge
· No scratches or bubbles
This is the spec we give for the nuarc units.

I would try something if you could. take any screen that hasnt been exposed yet and sit it in direct sunlight for 10-15 min and then wash it. If that fogs or hardens the emulsion then we know where the problem lies.

I am on the way out the dorr for the holiday weekend but I will check in to see how you are doing.

[Catspit Productions]

Thanks Apeshirt and Saati! I appreciate your help here. Looks like you guys have it covered. Nice!

[Leadfoot]

One other thing, did you remove the glass from the work lights? That is UV blocking as well. I have exposed successfully with just one 500 watt light bu two is more than enough. Some other great tips here. Please continue to post if you are still having issues...we will all do what we can to help you work it out.

[Catspit Productions]

That's a very good point Leadfoot. I didn't think of asking that. See how the community works? Nice job and thanks for bringing up something we overlooked.

Leadfoot is correct. The glass that comes in most work lamps will have a UV filter coating and they need to be removed for best results. You should make sure to do so if you have not done so already.

Nice team work here. Thanks to everyone!

[Shamax]

At this point, I'd say it's time to try a thing or two to rule out some factors or possible causes:

Wait for a sunny day, coat a small section of your screen, and don't worry about a film positive. Try to expose your screen just using sunlight. Leave it out there for a while (10-15 minutes tops on a bright day would be more than sufficient, I'd think), bring it back in and try to wash out. If the emulsion hardens, then you know your emulsion is working and the problem is just that not enough UV is getting to the screen on your exposure unit. If the emulsion still washes out after a long time in the sun, you've got a bad batch of emulsion.

Doesn't solve it in one fell swoop, but sometimes you just have to start ruling things out.