[chrisf116]

I know... I need to get an exposure calculator.

But in the meantime...

I have a home built exposure unit w/ 2 500w halogen lights 22" away from the screen. I need to expose a screen with fine lines. The image is attached. It is about 3" wide on the chest of the shirt, so the lines are maybe 1/16 to 1/8 of an inch.

The first time I tried, I exposed for 15 minutes and when I washed out, the lines were blown out (for example, corners such as in the "N" were rounded and connected if that makes sense lol. I should have taken pics).

My first thought was I underexposed, but after more research it seems that probably wasn't the case?

Please help!

 

[Greatzky]

what type of emulsion are you using? also did you remove the glass from your 2 worklights?
I have a single 500W light and I'm about the same distance away and i'm exposing a 110 mesh coated 1/1 in about 6 minutes. I am currently using SAATI PV (photopolymer).

 

[ScreenFoo]

Your emulsion type, mesh count/color, and coating technique are all very important parts of this equation.

 

[chrisf116]

Sorry, white 110 mesh coated once on each side. Emulsion is from Ryonet, I think it's called dual cure? The one you mix the diazo into. Glass has not been removed from the work lights.

 

[chrisf116]

Mesh is white.

 

[chrisf116]

Emulsion:

http://www.silkscreeningsupplies.com/product/CCDXPQT

Thanks!

 

[DanAxe]

How long are you working at washing the screen? IF you are over exposed but you keep blasting the screen with water for 20 minutes you will break it down, at least partially. Is the inside of the screen slimy or firm when you get it wet? 15 minutes is a long time with any modern emulsion chemistry.. The EXACT details on the emulsion will help a great deal.

IF you just want to give it another shot...cut your time in 1/2, Make sure your aren't washing your screen out in and area exposed to sun light (like outside), rinse your screen on both sides with alot of water so it gets really wet. Then use light pressure on the bottom of the screen(side that was closest to the light source). IF you are still trying to wash the screen out 5 minutes later...you are still over exposed. Reduce the time again and repeat.

 

[chrisf116]

Thanks, that helps a lot. At first it was firm but I guess as you said it started to break down and got slimy and I could also peel it off.

Should I remove the glass as well?

 

[chrisf116]

I was definitely washing it out for 10-15 minutes too lol

 

[DanAxe]

I'd leave the glass for 1...change 1 varible at a time. Once you have a good screen...if the exposure time is too long for your liking than removing the glass will speed things up. Also make sure the emlusion is DRY before you try and expose...You can't usually coat a screen and burn it an hour later. Let them dry a few hours or if in a humid part of the country maybe overnight.

 

[chrisf116]

Yea I let em dry overnight. I coated them a couple days ago.

 

[adawg2252]

Are these issues specific to trying to shoot this image? Or are you having similar problems while trying to expose other things as well?

Have you tried just throwing another positive that had better results to see if maybe the positive you're using is so fine that the lines just aren't printing dark enough?

How old is the emulsion since you sensitized it?

 

[superD70]

Remove the glass and expose for 25 min, you are under exposing if everything is washing off, after exposure wet both side of screen with warm water, let sit for 3 min, then wash out from ink side of screen

 

[chrisf116]

@adawg emulsion is about 3 weeks old. This is only my 2nd print, the other one came out fine but it was a big bold logo that was 8" wide by about 6" tall with no fine lines

 

[chrisf116]

@superD70 it's not all washing off, it just lost details around the small lines when you looked up close

 

[superD70]

Are you using CCI DXP?
Last time I used that with a halogen lamp I was exposing for 32 min @ 20" with a 230 white mesh coated 2-1, held halftones and fine lines just fine for me, was getting a solid 7 on a stoffer strip, get you a test strip and burn some tests, you are just pissing in the wind guessing

 

[DanAxe]

Ok so I'm assuming that it's still not working?
Your Film Positive? How was it generated? Ink Jet , Laser Printer, on Film, on vellum? You are looking for the Blackest, most dense ink deposit on the clearest carrier possible. If you have a bad positive...translucent...this could be much of your problem.

We didn't establish how you were maintaining contact between your positive and the screen during the exposure process. You need extremely good contact between them to keep the light from getting under the image and closing up the detail.

Also the screens that you dried for a couple of days, where are they and how well are they protected from light leaking in? Fogging the screens with even a small amount of light over a long period of time could be the problem as well.

It's usually one or more of the little things like this that causes this type of problem.

 

[ScreenFoo]

Dan's got some great suggestions there--From what you're saying, I'd guess somewhere between a bad positive and poor contact is the root of your problem.

Next time you do an exposure, try putting a piece of electrical tape next to the positive--if that washes out easily, but you have to scrub the artwork to get anything to wash out, darker positives would help.

If you're not doing anything but taping on the positive for contact with the stencil, you're not likely to have too good of luck with designs like that...

 

[sben763]

1 take off glass off light. It will block out quite a bit of UV light. 2 if you don't have a piece of glass for a positive contact I found some at lowes that doesn't contain any filters. It a thinner piece so I bought 2 and put silicon on edges and glued together. I helped someone build a set up. They are exposing 7-12 min dual cure CCI with a 1000w halogen. Depending on mesh, coating ect

Ther are a lot of good suggestions in the 2 post above also.