Looking to go LED...looking to hear the pros and cons...

[acescreen]

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!

[Dottonedan]

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!

In one breath, you prefer the idea of having the same exposure times for the different mesh, and at the bottom you mention the negative of the screen breakdown.   I think you're missing the point of the more accurate exposures for each mesh even with your current unit.

LED is a great way to go these days. Fast times, less bulb cost ect. Your questions needs to be, (Are the average LED units good enough for my shop and what I do?) If so, then it's a good buy. If not, then you need the higher end LED units.  For both high end low, on dual cure, you may need to post expose (for those really long runs of say 50k or more) ot waterbase printing.

No matter the brand, you should know and ask for the limitations. There are differences in each but many people can adjust as needed. If it were me, and I had to use a lesser due to price, I'd just not put anything in the art below a 10-7% dot if my machine gave me issues with it...but that's me.

[TCT]

The Workhorse unit is very aggressively priced, and my experience with Workhorse as a company(on this exact product and others) has been A+. One thing you will want to consider is if you ever plan on using a diazo emulsion. This unit was not designed for diazo and preforms very poorly with a diazo emulsion. Aside from that the unit was made very nicely and for the price, it's hard to go wrong.

[GaryG]

Sure, may babysit for a week?
We call it dialing in data and will most likely only last a day or two if you write it down.
Then it will be an old man on your way to faster output. 

Tech of the future with kinks mostly worked out.

[alan802]

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.

[Sbrem]

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 all the LED's as opposed to a point source would be the cause of the light scatter on the white mesh... just a thought.

Steve

[ZooCity]

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.

[Sbrem]

After reading all the threads on this topic of late, I'm thinking it makes sense to have both if you really need them. Go for the 5K or 7K MH, I've always liked our Violux 5000S.

Steve

[RonH]

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.

[RonH]

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.

I typed this up once and as I was about to send it my internet connection in the hotel was lost and it only sent the quotes. So here is my response.

Even though the UV Fluorescent units are at the bottom of the Exposure Unit Totem Pole and LED's are a popular exposure option, I am not sure that all LED units are a step up from UV Fluorescent.  I have run across LED units that closely mimic the old Fluorescent tubes by the placement of LEDs, thus they have similar results.

It is true that the LED units match up well to the PP emulsions, which results in some fast exposures.  When using Diazo or Dual Cure emulsions I find in most cases the exposures are similar in time to a 5K or 6K MH unit.  Although a lot is said about the speed of our LED units, that was not our main goal when we designed it.  Our goal was to design a unit using LED's that would match well against the long time standard of the industry the MH light source.  I have been traveling around the country doing demos in shops with our Starlight unit and I can tell you that most shops go looking for the hardest film they have ever printed before.  This has been a good test and so far we have been able to hold those jobs.  I am not going to tell you that there is not a job somewhere that we could have problems with, but so far we have been able to hold everything that has been thrown at us. As I say these things I want to make it clear that we are not trying to say that MH is a thing of the past.  I still feel there are shops that are going to continue using MH, and we will continue to manufacture them.  There are advantages to LED that most are aware of and we have shown many shops that the output of our LED unit is on a par with the MH units.

Ron Hopkins
NuArc Sales Mgr.
M&R Sales and Service Co.
ron.hopkins@mrprint.com
847-997-2487