Discharge and Our Vastex LED

[blue moon]

As I understand it:

Dual Cures get little to no benefit from sitting in the sun/post exposure.  Something about how the molecules position themselves.  I think it was a Saati article?  Or maybe Al posted some of his great wisdom about it....

It's the emulsions like Murakami's Aquasol and Saati's PHU that do benefit from post exposure.  The SBQ's if I remember right.  Someone please correct me if I am wrong.

If the bulbs are not emitting light in the correct frequencies for a dual cure, then the screen is doomed from the beginning.

Even using a chemical hardener will not give you the life expectancy (and detail) you desire.

Sorry to say Alan, yep you need a better light source.

I think you are right! dual cure supposedly does not benefit from post exposure as much. So it might be the light source after all.

pierre

[screenprintguy]

I'm not 100% convinced that the starlight puts out the optimum light for these emulsions either.

Diazo is 360nm
SBQ is 405nm

Starlight is 385nm

Speak with Diggler, he's running discharge screen using CCI-Green? some new dual cure of theirs, on his Starlight bullet proof. Someone else here, maybe Homer? Runs CCI HXT on their starlight bullet proof.

[Frog]

I'll correct my correction. I wondered if the addition of Diazo for hardening a Photopolymer emulsion, reduced the effect of post exposure, and was told by Murakami, no.
I, perhaps incorrectly, carried this over to dual cures.

[ScreenFoo]

I'll correct my correction. I wondered if the addition of Diazo for hardening a Photopolymer emulsion, reduced the effect of post exposure, and was told by Murakami, no.
I, perhaps incorrectly, carried this over to dual cures.

Isn't adding diazo to a photopolymer the definition of a dual cure? 

Yep its time to get that thing out of there the Richmond solarbeam you have is an excellent exposure unit. Fix it up and get back to work, and sanity.

This is what I've been thinking for some time on this subject...

[Homer]

we use CCI HXT with 1/2 bottle of diazo added - don't need a whole bottle, shot with a starlight, DTS - our screens are bullet proof too...we do DC/WB every single day, not one single issue.

Thanks to Mike for the heads up on the HXT, been over a year now, can't find anything better.

Al, man, you gotta move on from this issue. You suspected a faulty expo for a while now, time to make a move. see my tag line

[screenprintguy]

we use CCI HXT with 1/2 bottle of diazo added - don't need a whole bottle, shot with a starlight, DTS - our screens are bullet proof too...we do DC/WB every single day, not one single issue.

Thanks to Mike for the heads up on the HXT, been over a year now, can't find anything better.

Al, man, you gotta move on from this issue. You suspected a faulty expo for a while now, time to make a move. see my tag line

Glad it works for you too Jay! I think we are hitting almost 4 years of rocking HXT. I don't even use the diazo. Our discharge orders aren't over 2,000 peices, most of them are below 1,000, but Some times an order may call for a double stroke so I count those strokes as total use on the screen. I have some Discharge underbases that have gone past 3,000 strokes of use and are still like new. The only reason I don't add the Diazo right now is because our discharge orders dropped. When we get the starlight, because of the speed, I think we may go 100% HXT for everything and then it won't be an issue dosing a bucket with Diazo because I know it will be gone in less than a week, but right now I'll coat say 30 screens with HXT when I have a fresh discharge order, then what ever screens weren't used in that order are racked until next order, so It might go a few weeks before I open the bucket again. You get where I'm going. HXT can sit without diazo for a long time in the bucket and still be good. I had a bucket that got hidden behind a rack, 6 months later I found it, it had already been opened, gave it a whirl and it was like new. That might not have been so with diazo, but I can see diazo will make them last even longer as the very first testing we did with HXT was a half gal with and a half without. The diazo added a few more minutes to the exposure. The BIG FACTOR people miss with this emulsion is they try to RUSH the time. Let it cook and it will last like steel. Under expose it and watch it fail. Not bad for 45 bucks a gal either, =).

[Frog]

I'll correct my correction. I wondered if the addition of Diazo for hardening a Photopolymer emulsion, reduced the effect of post exposure, and was told by Murakami, no.
I, perhaps incorrectly, carried this over to dual cures.

Isn't adding diazo to a photopolymer the definition of a dual cure? 

Well, at this point, we need someone who really knows to chime in.

[jvanick]

when adding Diazo to a SBQ and since the Diazo has a optimum light sensitivity of 360NM, and the SBQ is up in the 405NM range, and my light source is around 385-390, what happens when the SBQ cures long before the Diazo cures?  Just wondering how the chemistry works?  I can totally understand the mixing in a MH/multi-spectral light source as the light is putting out both of those spectrums, but in a LED source, what's actually happening?

[T Shirt Farmer]

Vastex unit in my shop... on the fence with this topic as we have had hit and miss experiences with stencils.

[Homer]

@ Mike - we use Diazo on everything. DTS w/ Starlight on average, 30seconds to 1 min max, everything for 110 to 305, S MEsh and all.

We double stroke every DC print. 24 units to 1k pieces. always double stroke. I was taught a few tricks by some fellas at New Buffalo, so we double up....

[jvanick]

This is yet another instance of that the manufacturers of these units HAVE to start informing the buyers of what wavelength the LED's are putting out.

-AND-

the emulsion manufacturers HAVE to start informing the buyers of what wavelength the emulsions are most senstive at.

Playing this game because "it's a competitive advantage" is not in our best interest, and we shouldn't be letting them get away with it.

[ZooCity]

My understanding is that diazo or diazo added emulsions need complete exposure at initial exposure.  Could they benefit from post expo?  Probably somewhat but they won't be as strong as a correct initial exposure.  Somebody correct me if need be and/or put the science in there.

5k and up MH is superior to LED when we're solely discussing exposure strength as it relates to imaging using the current emulsions on the market.  Now, match an emulsion to a specific LED wavelength and this will change.  LED benefits are less power consumption, consumables, floor space, they do not, really cannot at this time, offer superior imaging.   

I agree jvanick, the fact that nobody will offer a histrogram of their output is just off.  I need to qualify that however, if it so happens that revealing the output range would allow a competing mfg to determine the proprietary LEDs being used and ape the other's product without putting in the R&D than that's fair enough. 

Nevertheless, a quality, high powered LED unit like the Starlight works well (or well enough to feel good about the other benefits) and is our shop's current choice of exposure method. 

[bimmridder]

Alan isn't ignoreing the replies here. He's chained to a manual press. I'm sure he'll respond when he is free.

[IntegrityShirts]

For comparison, we are now using an entry level SAATI LED unit at 50 second exposure time. Aquasol HV is giving us about 100-200 discharge prints straight out of bucket. If we put it out in the sun, we are getting 500+, even up to 1,000. We are also testing the SAATI PHU and are getting about twice as much on the discharge runs. All of these are without hardener.

pierre

Off topic, but I have had similar results as it relates to aquasol and saati phu. The PHU lasts MUCH longer than aquasol did with DC or WB runs.

Alan, time to punt. Fix the 8k, or was it 10k, light source and don't look back. I've said it before and I'll say it again, the quality of these units solely rides on where they source their LED's from. M&R either contracted the company that makes theirs to have them made in a specific wavelength, or just bought their 395nm units that are EXPONENTIALLY more expensive than what you can find online or on aliexpress.

[alan802]

Sorry I have been out for a while and I skimmed through the replies best I could. 

I have demo'd the Starlight and with the few screens we did I liked what I saw.  I didn't get to run a long plastisol job on the screens to see if they'd hold up and definitely didn't do a discharge run.

And on the subject of whether or not it's the expo unit, I immediately thought it was the problem simply because on Wednesday we were shooting screens with a Richmond and over the course of 7 or 8 years we never had a problem.  Thursday afternoon we are shooting screens with a Vastex LED and you all know what we've been dealing with since then.  I know that sounds way too simple and there is no way the answer lies in that theory, but those are the facts and as basic as we can get them.

As far as the screens being dry, dry as a bone within about 2 hours after a coat job.  Joe C measured a batch of screens that my guy had coated about 2 hours prior, and used his fancy moisture meter and they were "superb" I believe were Joe's words. 

I'll take a better look at the replies over the weekend and try to address everything.  Trust me, I wouldn't have fought through all of this for almost a year if I thought it was the exposure unit only.  I tried my best to make sure I didn't call something a loser if it really wasn't.  I feel like I gave this thing a better shot at proving itself than anyone else would have given the circumstances.  I've been doubting my abilities and my knowledge the entire time we've had this unit and have actually learned a hell of a lot more from all the failures than I ever would have running the Richmond this past year.  For that I am grateful.  Yall have a good weekend and those who can't stay away from this place over Saturday and Sunday we can continue this.