Opportunity is missed by most people because it is dressed in overalls and looks like work. - Thomas Edison
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
Since buying the Vastex LED we haven't had much need to do any discharge work so I was excited this past week to see 3 new discharge jobs come in but I was apprehensive at the same time with our poor results with most every aspect of our LED unit. I had this really detailed review of what we've seen, the whole routine we used to make the screens, the emulsions tried, etc, but I just deleted it all and I can sum it all up in one word: SUCK. It's my own fault, how in the hell could I have thought that I'd get anything other than poor results? I still can't believe I thought it would be fine. So not only can we not produce a good sim process screen above 50lpi, we can't seriously do any waterbased or discharge printing until I jump through so many hoops, do a lot of back flips, hold my finger in the air just right while wearing a tin foil hat, AND PRAY the screen holds up. I don't like those options. This shop has steadily progressed over the years into something we're all proud of, and to think that we've had to take a step backwards in our quest to be one of the best doesn't sit right with me. I know some will think I'm an insane person, that what I'm asking of a piece of equipment isn't reasonable, I need to get over myself and deal with it's capabilities like everyone else because we're not special...I don't see it that way. Anything less than our best isn't good enough, and over the last year I've tried so hard to keep moving this shop in the right direction and I've finally hit a plateau (actually we've digressed) due to something that did not come with any fine print or disclosures like what we've had to deal with. It's very bothersome to me. How could I be the 1st person (that I know of) to have something negative to say publicly about an LED exposure unit? Were we the first to actually put an exposure calculator on one? Were we the 1st to fun a few hundred impressions on a screen and have the stencil fail? Surely not. Now were we the 1st of active forum members to do those things I asked? Again, I seriously doubt it.I can say that if you're seriously looking into this particular LED for your next exposure unit, you still could love the product depending on what you ask it to do. If you want to do high-end sim process work, it's not for you. If you want to do virtually any WB or DC work on an auto...probably not for you. If you use thicker stencils, not for you. Low mesh counts (thicker stencils)...again, not for you. What is it good at? Doesn't use much energy, the bulbs don't weaken much over time, it doesn't put out much heat, it will do the basic, run of the mill spot color stuff all day long without much problem until you get the screens on press for longer runs, then it really isn't very good at all. I went further with these DC screens than I thought would be necessary so I wouldn't have to worry much about the screens breaking down on press. I used a very good water resistant emulsion, a dual cure, tripled the recommended exposure time, blockout, hardener, 10 minute post exposure on the expo unit, sat it out in the sun for an hour, then let them sit for 24 hours before we used them. The only thing I haven't done with regards to DC screens is test a ton of different emulsions. I feel confident though since our results were on par with what we're seeing with our plastisol screens and at least 15 different emulsions, I think I'd be wasting my time testing out a bunch of DC emulsions. And everyone that knows me knows that I didn't just put some emulsion on a screen and shoot them and call it "tested", and to do all of that again for DC ink isn't going to happen any time soon.Am I out of line to expect this expo unit to be able to consistently produce single digit % halftones of even 50lpi? What would everyone here expect to be able to get on a standard exposure calculator as far as halftones go? 10% at 65lpi? 5% at 50lpi? Or am I shooting too high? So with ALL of that being said, who wants to buy a used Vastex LED unit?
I will tell you that I'm having issues with the starlight exposing Saati PHU-2 emulsion. The guys from Saati are involved and I'll be testing their 300w light next week.I believe that part of our issue is that we've been getting almost 40% EOM and that it just may be too thick for the starlight to completely penetrate without over cooking the shirt side of the screen. I've got a batch of screens that are more around 18-20% EOM that we'll be trying next week as well to see if that's it.But, between the edge breakdown issues as well as the emulsion softening on longish discharge runs even when exposed to a 7+ on the stouffer strip, I'm not super happy right now. (This is following all the steps and instructions from Saati)I can say that halftone detail has been awesome, and that for plastisol jobs, I'd likely be perfectly happy...SP1400 and the Starlight is not a fun combination... in order to get solid 7's, we were exposing at nearly 2 minutes!
A dual wavelength LED unit of say 360/405 seems like it could be perfect (no idea how to engineer that).
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Topic: Discharge and Our Vastex LED (Read 8075 times)
