Before You Went LED, What Were You Using?

[Gilligan]

how underexposed do you have to be, or how aggressively are you rinsing the inside of the screen?

My tests here over the last few days have shown that I can be at least 3 steps underexposed, and the emulsion doesn't get any thinner.

Yeah, I've never had a slimy backside (too much info? ) but have been under exposed according to stouffer strip.

[alan802]

I mentioned our D-max wasn't as good as it once was, but over the years it's gone from horrible, to great, to average, back to great, and today it's above average.  If your D-max is low, you'll overcook the emulsion in those areas, unless you know that going in and are underexposing on purpose to get around your weak films, which I'll admit we have done more recently.  If we had a significant dropoff in D-max and never noticed it we would still be shooting screens for the same amount of time and wouldn't have been underexposing screens most likely.  The LED's on our unit simply don't fully cross-link the emulsion we've used since buying it, that's the problem.  There are ways around the issues, and I'll likely start looking for a more LED friendly emulsion, but I don't want to do that.  Some of you will just have to trust that I've put a lot of time and effort into these problems and it's really simple to figure out.  Our D-max has drifted over the years, but our MH unit stayed the same, we struggled on some higher mesh screens and halftones with inkjet film, Epson printer, Accurip, etc. but everyone would.  We went about 7 years from wearing out emulsion and those days were because I didn't know what the hell I was doing and was using 85 duro blades and 50psi on the heads just to clear ink from a screen, and those settings will break down even the most hardy emulsions.  So you go from being able to get 2500 strokes out of a discharge screen shot with the Richmond to 5 on our first DC screen shot with the LED...5 strokes, that's not a typo, 5.  When you've got a blowtorch and weak film you're going to have some complications. 

If you have imagesetter type film, and a blowtorch you can get away with just about anything and get your detail out of the screen.  With the crazy good exposure latitude with the emulsions we were using and a great light source and great film, it's hard to screw up.  Anything less than optimum tools you will see a decline in reproduction of your artwork from film to screen.  I've never been one to try and get a 65lpi 3% halftone dot on a 305 because I don't think it's worth our time to try and do, and I can live with some of the issues we're having with our screens because there isn't much I can do about it.  I made a decision and I have to live with it.  I made the wrong decision, and I can freely admit that to all of you guys because it doesn't bother me to disclose that to you.  Many wouldn't come close to admitting they bought something they shouldn't have, or took a job they shouldn't have, or whatever the case may be.  I can't go back and change the decision now, and there was the question in my mind on whether or not I should contact M&R and see how fast they could get a Starlight to me, or Richmond to see if they could overnight a new touch panel, or run with the easiest, most convenient route and a piece of equipment from a good manufacturer, and one of the best suppliers in the industry, and we all know what I did.  I did weigh the other options quite heavily, and I thought that I might could get with the big guy in Chicago and have a Starlight here really quickly, but I didn't want to call on anyone to get us out of a bind if I had other options that I felt were good at the time.  And as far as the Vastex goes, I would venture to guess it's still one of the better LED's on the market, but trusting many others here and our own experiences with our LED, I would also wager a heavy sum that the Starlight would have been the better choice for us.  I don't know for sure but I think the larger Starlight comparable to our Vastex has 3 to 4 times the diodes in it.  Although I'll contend that single-point is best, that many more diodes, given that they are of equal or better (likely the case here) output, the Starlight would spank the competition.  And if Starlight users can shoot a 180/48 with 15% EOM, pure photpolymer emulsion for 15 seconds and use that screen for a 2K piece discharge job with no breakdown, we have a winner winner chicken dinner in the LED contest. 

Our film density was off, but that kept us from getting some of the fine lines and details and maybe a few dozen exposures we had to adjust, but I look at every piece of film that we burn now and I know how to adjust things on the fly, so it's not the problem in the grand scheme of things.  With our equipment and the way we do things, our LED simply isn't as good as our 15 year-old Richmond MH unit, end of story.

[Frog]

* This thread started in March, and in May, took off again, but devolved into mudslinging and arguments that obscured any real facts and information. I performed a little surgery, but there are probably still some statements that will seem a little odd in their new altered context. Otherwise, most will see it as a great improvement!

[tonypep]

Sorry lost interest. Perhaps able to contribute  but do not care for split threads. Busy and not able to comment much however this is why I do not. There is another.

[CSPGarrett]

I am still working on exposure times for our new Workhorse LED.  Have gotten them pretty down packed for the last 7 gallons of Saati textile PV day in and out.  I am switching over to Ulano Orange after I finish this last half gallon so have to start testing now.  I am hoping to see improvement over current textile PV times.  I am at 3 minutes for a 1/1 round coat at 10-12 seconds per side on a 125 - 158 white mesh on average. 

I really want to cut that in half with Orange?  I know some people have said times in the 18-45 second range, but I don't need it THAT fast since we can't wash them out that fast.

Prior I was using the Point 1000 (I know it isn't the best, but was told it would work).  I never got the point 1000 to give me 100% exposure and couldn't use it form a lot of screens without letting it cool down since it got too hot.  But the Workhorse LED has been great.  Outputting film at a 10 deposit level on accurip for really dark films, awesome results so far.

Detail has held very well too, even when doing really high detail/text artwork on 125 mesh.

[jvanick]

I am having MAJOR issues here since switching back to SP1400... it may be related to viscosity changes after switching,  but I really don't know at this point.

I'll keep updating as I learn new info, bit something is NOT right and it's driving me to drink heavily, which is not what I need when we have over 50 jobs in the backlog and screens are  breaking down on press.

[TCT]

I am having MAJOR issues here since switching back to SP1400... it may be related to viscosity changes after switching,  but I really don't know at this point.

I'll keep updating as I learn new info, bit something is NOT right and it's driving me to drink heavily, which is not what I need when we have over 50 jobs in the backlog and screens are  breaking down on press.

So are you having breakdown issues?

[ebscreen]

What kind of ink Jvanick? You were my one positive response on SP1400
and LEDs!

Probably pertinent for anyone having or not having issues to mention the kind of inks.
Plastisol and discharge are worlds apart when it comes to stencil durability.

[jvanick]

Plastisol is even breaking down right now.  Horizontal chatter marks.

We ran 20k on sp1400w in November last year with no problems. ..

We ran 20 (twenty) pcs today and we were starting to have issues...

It may be viscosity issues, starting to track EVERY variable...

But  at this point,  we have no idea what's going in as we can pull older screens off the shelf and have no issues.

Seriously,  I am pulling my hair out here.

[alan802]

I am having MAJOR issues here since switching back to SP1400... it may be related to viscosity changes after switching,  but I really don't know at this point.

I'll keep updating as I learn new info, bit something is NOT right and it's driving me to drink heavily, which is not what I need when we have over 50 jobs in the backlog and screens are  breaking down on press.

I could look it up but I am feeling lazy, what exposure unit are you running?  LED I presume.

[Homer]

I'm tossing a guess your emulsion was frozen at one point.

[jvanick]

We're on a starlight...

This is 3 different batches of emulsion... however, I guess it's possible that our supplier screwed up and let it freeze in their warehouse over the winter...

I have a gallon of Ulano Proclaim EC coming in today that I'm going to give a shot...

[Homer]

stupid question but are all the LED's turning on? Have you tried cooking a screen for 5+ minutes to see what happens?

[jvanick]

That's the rub here... if I take an old screen that was coated a month or so back with SP1400-W and throw it at the normal time (40 sec), NO issues at all.

-J

[alan802]

And you were running the Starlight in November with great results on the 1400?  If so that's enough for me to say you got a bad batch of emulsion and your supplier should replace at zero cost.  If the Ulano fails then I'd say you've got a problem you need to try and hammer out, but if it passes then there's a 99% chance the 1400 emulsion was junk.