Sorry to bring this up. I realize this has been covered several times and the topic can get contentious. I feel like I have a specific circumstance and thought I'd just throw it out there. Y'all seem like bunch of knowledgeable printing nerds(in a good way!!). I've read through the thread from last may. My back kind of hurts now from sitting at my computer reading all of it....... but here goes.
I've been screen printing for nearly 20 years. I built my first exposure unit with household fluorescent bulbs. went through various used units. Bought a used Olec AL53 more than 10 years ago and still use it. It works just fine and I might stick with it. BUT.......I'm moving into a new and very small space next month and thought about switching to an LED exposure unit. I mostly print on paper with water based inks. some manual but mostly on an auto- 25x38 M&R saturn. I probably avg 1200-1500 impressions per week- sometimes double that and some weeks I don't even turn the press on. I print even smaller volume with textiles(a few hundred shirts per week- max) with a fairly even split between water based and plastisol inks. all manual. and again some weeks I don't even turn my dryer on. Just trying to get the point across that I do not print high volume. I'm one of the teeny shops. just me and a couple of part timers.
The biggest issue in making my decision is due to the lack of larger sized LED units on the market right now. My largest frames are 42"x50"- OD. The only manufacturer I can find that makes an LED unit to fit this sized frame is Lawson. I have seen that m&r is making a large unit now but its CTS. I work with a lot of fine artists making limited edition prints and I would like to continue using film positives to have the ability to make handmade marks on them. I've never used or been around any Lawson equipment. Any opinions on their stuff?
I've never used an LED unit. The concept of less amps and less heat are the biggest draw for the small shop space I'm moving to. But I'm very concerned about how hardy my stencils will be when running 500 pieces on the auto flatbed press. With my current screen room set up, if there is a too much humidity before or after exposure, my screens can become sticky once I pour a qt of water based ink on it and start running a job (sticky on the print side of the stencil). This causes the paper to stick to the back of the screen, despite the vacuum bed. This is obviously avoidable with climate control but my point is that if this happens with a 5k MH, I fear it could be worse with LED. I'm in Austin, TX btw. it's warm and humid most of the year.
I also realize that there can be issues retaining detail with a multi-point light source due to under-cutting but I don't tend to find printers complaining about that as much as I do with the problem of achieving a fully cured stencil/ or at least hardy enough stencil to make it through a run on an auto press. especially with water based ink products. Am I correct on that?
I currently use chromaline CP tex- "water resistant" direct diazo emulsion. coated 2/2 with the sharp edge. but i'm not married to that product or coating technique. I run exposures on time not LU. about 220 sec for a 305 yellow mesh. 150 sec for a white 156. I don't care if the LED were to take less or more time than this. I generally move pretty slow with most things in life.
Sorry again if this is an annoying subject to bring up. Any input is much appreciated.
Cheers!
-josh
