Opportunity is missed by most people because it is dressed in overalls and looks like work. - Thomas Edison
Considering an LED, to be exact the Workhorse Lumitron unit. Right now we are using an older Atlas beamed blacklight unit. We shoot our standard plastisol screens for a set time and our waterbase screens for a longer set time.... all with great detail, fine lines and up to about a 55lpi halftone with no issues down to about a 5-10% dot. After doing some research and talking with some folks, the main "pro" is much quicker exposure times. "CONS" you may loose some detail and maybe not get as fine of a halftone dot. Also it sounds like exposure times really need to be dialed in and you may go 15 seconds on one mesh count and then change to 30 sec for another.....overall it sounds like lots of babysitting for different mesh counts to ensure getting a solid and also like you may loose detail. Also we also want to make sure we can fully expose our waterbase screens all the way through as we are having issues with screen break down now with our current unit.Any input would help. THanks for your time!
Actually, exposure latitude is not bad for yellow mesh if you find the right emulsion. For example, when we were slammed during the summer months and I had a new crew I simplified our exposure process to this: White mesh we shot for 15 seconds and yellow mesh (excluding process screens) for spot colors stuff was 30 seconds. Yellow mesh didn't really care if it was shot for 20 seconds or 120 seconds, it performed almost the same (spot color stuff only, not talking halftones). White mesh...not so much. There seems to be a huge amount of light scattering going on with our white mesh screens that I didn't have as much of an issue with the metal halide unit. We've got our EOMs down to about as low as we can go for each mesh count but all of my testing found that there wasn't much of a difference between a spot color screen that was shot for 30 seconds or 90 seconds. We did have to adjust things when we had halftones or fine lines to develop but for the majority of the jobs we were printing those 2 burn times got us through. We still had to tape the screens for the usual breakdown but I think most will be surprised by the latitude. I believe it's true that to really fine tune or calibrate perfect burn times, for high detail printing, the latitude shrinks A LOT.
I think any quality LED unit would be an upgrade from black light tubes. Tubes put out weak, highly diffuse light. I imagine even a not so perfectly designed LED unit could trump or at the very least match your current one. My main advice echoes Alex's- do not go with a more affordable LED if you are exposing diazo added emulsions. All the talk about fast exposure and cool operation, etc. applies to fast shooting PP emulsions responding well to the spectral output of the commonly used LEDs. When you apply it to diazo, dual cure, diazo added photopolymer emulsions it all goes out the window. We use the larger Starlight unit, which many consider the best/strongest unit on the market currently, with diazo added emulsions and yes, it works, but it is far inferior to metal halide in every aspect save power consumption. If you use diazo added or see yourself doing so in the future my advice is scoop up a used 5k or stronger metal halide.