[TableSyrup]

Ok, I'm using Murakami Photocure BLU
I have a Vacuum lid UFBL Fluorescent unit with 10 20W bulbs.

I've been coating my screens with the dull edge of my coater...
2 Coats on garment side, and 1 on the ink side.

I burned a screen on Sunday for 9 Minutes.
I threw a Stouffer 21 Step on it and I got a solid step 9

So, per their instructions, they say multiply by .5 for decreasing 2 steps.

I haven't burned another screen yet (Don't need to), but...
really??? 4.5 Minutes????

Is this just because of the particular emulsion I'm using???
Seems dang fast for a Fluor unit ????
Or am I maybe not getting a thick enough coat of emulsion???

Dude from Murakami told me to expect 15 minutes or more so I'm amazed.

Just wondering if this is out of the norm... which may indicate some other condition such as too much heat at exposure unit or too little emulsion or something.

I printed with that screen and didn't have any issues (Other than I suck)... but it has me wondering.

Thanks for humoring me.

 

[20vK]

What is the thread count of the screen?

That makes a difference - I've had to do an exposure test on all my screens.

Richie

 

[TableSyrup]

Yeah, sorry, didn't mention that.

The 9 minute one was 156

I ran 2 trials prior to the Stouffer showing up, both on 110, and found 15 to be too much, and also 12 to be too much, so dropped to 9 on this 156 - at which time I had received my Stouffer, and threw that on... was a step 9..... so according to their stuff... I'll run my next one at 4.5 minutes, which should give me a solid 7

I'm tryin to get better one hit white on black, and I know part of it is my technique, part is my ink, but now I'm wondering if I'm maybe also not getting a deep enough 'ink well' - too little emulsion? And maybe that's why I'm exposing so fast? (That's why I'm wondering about the time..... if the time seems fast, then maybe I am coating too thin)

I don't have a lot of experience yet, so I just don't know if this is out of the norm.

I know the emulsion I am using should expose fast... "3-5 times faster than diazo"
But I'm confused, cause even the manufacturer told me to expect 15+ minutes.

 

[sben763]

I have a florescent unit use S.E.X emulsion from performace screen. 110-156 3:00. 230-280 2:15. 305-380 1:30. Photopolymer emulsions can expose fast. I may adjust 15 sec more if no detail or halftones or decrease by 15 if all halftones.

 

[TableSyrup]

Cool.... thanx again sben763

 

[TableSyrup]

One other Q on this

After exposing for 9 minutes (Which was too much)

My film kinda peeled off the screen. (Inkjet - R2200 and if I remember correctly either Afford-A-Black or Econo-Black film)
The entire film, not just the printed area.

Is this normal? Or does this happen with overexposure?

My screens had dried with the fan on in the rack for a good 4 or so hours, and then with it off for a good 24 hours.
Pretty sure they were completely dry.
Temp around 65-68 degrees, and not sure about humidity, couple rainy days here and there, but not noticeably above norm in the basement (Minneapolis MN)

 

[ScreenFoo]

Are you sure it's a SOLID step 9? When I hit a solid step 6, steps through ten or eleven won't wash out--it's where the color change stops that you count as solid.... (Misleading, I know)

 

[TableSyrup]

Well... your post made me go read the test info on Ulano's site again.

Ummm... yeah.... my bad

"The guide numbers are clear on the film so they get 100% exposure. You will know you have a Solid Step, because you won't see a difference between the guide number, (7), and the patch of stencil around it. If you have a 'crusty' step, you know that unexposed stencil on the inside of the screen has broken down and washed away with water. Not Solid!"

Ok.... so then, based on that.... I'm a 7 at nine minutes

My 10 partially blew out, 9 held, but I can still see the step number in 9 and 8.

I was playin rookie.... and mr can't read or retain what he reads thought I wanted the last step that held.

 

[ScreenFoo]

It gets worse--I look at the color change on the *inside* of my screen. It's easy to get the print side of the stencil cured, but it's the cure on the other side that will matter when you're doing large runs, need solvent/water resistance, and are reclaiming. Although you shouldn't let it get you down, seems like pretty much everyone underexposes as SOP anyway...

 

[TableSyrup]

I checked the last one (The 9 minute) with a paper towel, rubbed both sides of the screen and didn't transfer any color....

I don't know a better way to test for this, outside the Stouffer test.

Edit: Ah, I follow.... you mean you gauge the Stouffer off the inside result. Gocha.

I'll look tonight. Maybe I'm a 6
The LADIES say I'm a 10, but whatever...

 

[Alan Buffington]

Try to run a step test exposure on your particular unit with your film.
Step test instructions: murakamiscreen dot com.
[media]http://www.murakamiscreen.com/documents/StepTestInstructions.pdf[/media]Underexposed emulsion is only an image, a production screen however is completely exposed to prevent breakdown while still exhibiting good details.

Al

 

[Alan Buffington]

Sometimes a long exposure can increase the 'tack' or surface adhesion of the emulison to the film. Simple solution is to spread a little talc or baby powder, on the bottom of the screen to prevent the film from adhering to the emulsion.

Alan Buffington
Murakami Screen USA