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Discussion Starter #1
I got a dehumidifier and my stencil's are turning out better now.

However. I burned a new screen twice. I put two coats on each side. Before I had only been doing one coat. The first coat was very sloppy. I ended up with emulsion all the way over the wood.

When I washed out the image. Chunks of emulsion started ripping off in the corners. I thought something was wrong, so I used stencil remover and started over.

The second time I still had some emulsion rip off in two corners. Both in areas where one coat went further out than the other coats.

Is this just from a poor coating job, or could something else be going on?
 

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It could be from the coating. Sometimes thick areas don't expose properly and then slough off during washout. But it could be something on the screen. Were the screens degreased before being coated? If not, that might be the culprit.
 

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Discussion Starter #3
Yeah, I used degreaser.

It could be from the coating. Sometimes thick areas don't expose properly and then slough off during washout. But it could be something on the screen. Were the screens degreased before being coated? If not, that might be the culprit.
 

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It's not your emulsion or how you coat your screens
the problem you have is exposure....

the thicker your coating, the more exposing you need
If you want to expose faster, coat 1 over 2

Obviously you need to have your screens prepped properly
and last..... make sure your emulsion is not too old
 

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Discussion Starter #6 (Edited)
The emulsion is new.

What do you mean by coat 1 over 2? I don't understand your terminology?

I did set my screen with the two coats up. I have been struggling for a week to get my prints to turn out right. I've been going crazy, especially with the white ink.

This screen was for white. The first print I did was my best white print ever, and this is after doing hundreds of prints during the past week. I have a huge pile of shirts that are completely covered inside and out with prints. lol.

I'm so relieved. I having serious trouble getting the white ink to go through the mesh on the first pass. Once I got some ink on the shirt, each pass after that was easy. But if the first pass wasn't perfect, the end result turned out like crap. I'd get a sand paper like effect. It is much easier to get a good first print with the white by having two coats of emulsion on my screen! I'm thankful for the Ryonet video on youtube that recommended multiple coats when printing with white. That video has saved the day.

I had done two test screens before. I printed an eagle multiple times across a piece of film. I used a manila envelope to partially cover up the film and exposed each eagle a different amount of time. I did it twice and determined that it came out the best at 5 minutes. (I'm using a Lawson Quest, which is basically a glorified 500 watt Halogen work lamp).

Are you saying that I need to let it expose longer now since I applied two coats to each side instead of just one? I wondered about that. All the materials I have talk about changing the exposure time for mesh count, but never any mention of changing the exposure time for coats of emulsion.

I ordered some more emulsion, haze remover, and more screens today. So I'll be doing a lot more practicing and experimentation here shortly.



It's not your emulsion or how you coat your screens
the problem you have is exposure....

the thicker your coating, the more exposing you need
If you want to expose faster, coat 1 over 2

Obviously you need to have your screens prepped properly
and last..... make sure your emulsion is not too old
 

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As for the emulsion coating it is VERY important to get a smooth even and consistent coat on your screens. Putting multiple coats using the round side of your scoop coater will cause your exposure time to go up significantly. A thicker stencil hold better detail, higher resolution, lasts longer, and allows for a more opaque ink layer on the shirt. If you have a weaker light source - you might have to use a 1 coat print side, 1 coat squeggie side with the sharp edge of the coater.

Also, if the film ain't TIGHT against the screen, you'll have problems.
 

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The first responsibility of every screen maker is to harden the stencil so it stays in the mesh and doesn't dissolve and rinse down the drain.

Stencils are easy. If it stays in the mesh it was crosslinked. If it dissolves, it didn't get enough invisible UV-A exposure to cross link the stencil and hold it in the mesh.

Measure stencil hardness with a Stouffer 21 Step Sensitivity guide and aim for a solid step #7.

http://www.t-shirtforums.com/screen-printing/t58936.html#post351087http://www.t-shirtforums.com/screen-printing/t19817.html#post121127
 

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Discussion Starter #10
I have a scoop coater. I use the sharp side. I'm still rather sloppy with it however.

I have a Lawson Nova, which is basically a Halogen on a metal stand. You set a piece of glass over the positive. I'm thinking of taking a few pieces of drywall the same size as the piece of glass, staking them up, putting a piece of black bedsheet over it, then sitting the frame over that. That way the mesh and the positive will be squeezed in between the glass and the sheet covered drywall.

However. Now that I have this dehumidifier running, my stencils are coming out pretty good. I was getting some really bad ones before I got the dehumidifier.

As for the emulsion coating it is VERY important to get a smooth even and consistent coat on your screens. Putting multiple coats using the round side of your scoop coater will cause your exposure time to go up significantly. A thicker stencil hold better detail, higher resolution, lasts longer, and allows for a more opaque ink layer on the shirt. If you have a weaker light source - you might have to use a 1 coat print side, 1 coat squeegee side with the sharp edge of the coater.

I spent days and dozens of test shirts trying to white on a green shirt to come out good before. Now that I have a stencil made with two coats (each side) instead of one, it is coming out 100%+ better. I definately will not be going back to the one coating.





Also, if the film ain't TIGHT against the screen, you'll have problems.
 

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If the dehumidifier improves your burning, then you weren't drying a thick layer of emulsion well enough. Give screens plenty of time to dry. Also, what I do with my scoop coater is to apply a layer on each side of the screen with the rounded side, bottom of the screen then the inside, then I use the sharp side to scrap extra emulsion off and make the layers more uniform.

Even with the glass holding it down, your film may not be completely flush with the screen mesh, which can cause problems in burning, with detail and definition. You may want to cut out a thick piece of foam to fit inside your screen, and then have the screen on top of the foam with the film on top of the mesh and the glass on top of that.
 

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Are you using Lawson SBQ-510? I expose for 10 mins at ~20in with a 500W halogen, per Lawson recommendations. This is with one coat per side.

Also, try drying it with a hair dryer. Keep the dryer moving and dont let the emulsion get above 100F. Never had a problem.

I turn my screen over on a black board shirt side up, tape the positives to it, put a piece of glass about the size of the emulsion on it, then a larger piece over that to weigh it down. You may also find that you can kind of "squeegee" the air out of between the positive and the emulsion after you lay the glass.
 

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Discussion Starter #13
Really 20 minutes? Lawson never gave me any instructions with the thing.

I did some test burns and determined that 5 minutes was my optimal time. Maybe I was just coating it to thin.

I ordered some stuff from Ryonet today and requested one of their ten dollar "exposure calculators" that you put in the corner.

I've burned some screens that came out awesome with the Lawson Quest. However, I have one 156 mesh screen that is hopeless. When I went to mark the center points with a t-square I found the joints were even 90 degree angles. Each time i hose it down it warps worse and worse. Each time I burn it somewhere in the print area it comes out looking like crap.

I ordered a few aluminum frames with higher mesh counts today.

Are you using Lawson SBQ-510? I expose for 10 mins at ~20in with a 500W halogen, per Lawson recommendations. This is with one coat per side.

Also, try drying it with a hair dryer. Keep the dryer moving and dont let the emulsion get above 100F. Never had a problem.

I turn my screen over on a black board shirt side up, tape the positives to it, put a piece of glass about the size of the emulsion on it, then a larger piece over that to weigh it down. You may also find that you can kind of "squeegee" the air out of between the positive and the emulsion after you lay the glass.
 

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Discussion Starter #14
I just got my $10 exposure calculator from Ryonet and it's the same one in your picture.

I just exposed a screen at what I thought was my optimum time and it was way under exposed.

The first responsibility of every screen maker is to harden the stencil so it stays in the mesh and doesn't dissolve and rinse down the drain.

Stencils are easy. If it stays in the mesh it was crosslinked. If it dissolves, it didn't get enough invisible UV-A exposure to cross link the stencil and hold it in the mesh.

Measure stencil hardness with a Stouffer 21 Step Sensitivity guide and aim for a solid step #7.

http://www.t-shirtforums.com/screen-printing/t58936.html#post351087
 

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The only time I've had a hard time with emulsion washing off in clumps has been when the emulsion was too thick a couple of times. Otherwise, it's turned out great everytime. I use the thin edge of the scoop coater and apply a coat to both sides of the screen. I dry the screens for about 6 hours in a rack then make sure they are dry before I use them. I also make sure my water pressure is not hard when washing them out and I don't wash out either side longer than a minute each. Then I blot the excess water off the screen (don't rub) and I dry the screen completely using a fan. I very rarely have a bad screen result.
 

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Discussion Starter #16
Actually I'm using SBA-500. According to their website, 500 exposes faster but is harder to reclaim.

However, after used one of those 21 step guides, it showed that my screen was way underexposed at 5 minutes. I have up it to 8.5 minutes now.

Are you using Lawson SBQ-510? I expose for 10 mins at ~20in with a 500W halogen, per Lawson recommendations. This is with one coat per side.

Also, try drying it with a hair dryer. Keep the dryer moving and dont let the emulsion get above 100F. Never had a problem.

I turn my screen over on a black board shirt side up, tape the positives to it, put a piece of glass about the size of the emulsion on it, then a larger piece over that to weigh it down. You may also find that you can kind of "squeegee" the air out of between the positive and the emulsion after you lay the glass.
 

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It seems that there are a very high number of posts with exposure and coating problems on this forum. I know everyone is not in a position to have a Uv exposure unit with vacumn drawdown blanket.I am so pleased I have as screen making is time consuming enough without needing to keep finding your optimum exposure time constantly,and redoing screens that haven't turned out properly.The thought of exposing a screen for 8mins+ makes me shudder.I expose in 90 seconds with my lightbox,using Ulano 925WR emulsion.I reclaim,degrease and coat exactly the same way each time,knowledge gained through 15 years of experience.So when you find the winning formula for you remember it,repeat it and above all try to keep things simple and straightforward so you can easily replicate good results everytime.:)
 
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