What LED exposure unit is the best performing?

[im_mcguire]

We are in the market, and we are just trying to see if there is one that stands out better than another?
We used to run the Workhorse LED lumitron, and that was fine, but it was a 3 year old model. I’m curious if anything new has come out that might be better?

Thanks for any information!

[Nation03]

I think the Starlight has the crown to on LED units from the reviews I've seen. I have the Ryonet LED/drying cabinet combo and it makes a pretty nice screen. My biggest complaint about it is that you need to manually engage the light after the vacuum draws all the way and after the light goes out the vacuum still runs. I wish they had an automatic dwell timer like most other models have.

[Cole]

If you aren't using a CTS and are still using film, you might want to consider a single light source exposure unit with a metal halide. Since LED units have rows of lights, you are bound to get some undercutting on your halftones and fine lines. With a single light source, it's harder for the light to wrap around your film and potentially ruin the sharpness of your lines and dots. With CTS, you have wax or ink that's actually "printed" onto the emulsion, so there's no way for any light to undercut your artwork. I use an LED unit myself, but if I could go back, I would probably go with a metal halide. If you have your heart set on LED, definitely go with a Starlight. It's the best out there.

[Dottonedan]

If I’m not mistaken, you may like to eventually end up doing discharge and waterbase. For that reason, you may prefer to choose the MH type of exposure units.


A lot of people early on, have reported switching back to a MH when their shop is focused on doing water base and Discharge since these emulsions need to reach a certain light wavelength for a period of time.  While working at JNJ, we had both so we kept both and most times when doing DC, we used the MH but more so simply because we could and it assured us a good exposed screen. The fact is, we did use the LED on DC and there was a difference in durability but to my knowledge, a lot of that was due to not creating a calculated exposure just for the DC using LED. I think at the current DC and LED exposure, our results would show to not hold smaller dots in 65lpi (as well as it did with MH. If the runs were longer, we would burn two of those screens. If not ever deciding to do WATERBASE, then the M&R LED would be fine for anything.


I’ve only heard that the go to for LED is the M&R. A lot of that is because the experiences are really good with the LED (if you are not a water base shop). Add to that, Rich Hoffman at the time, posted where their's was at with testing results and showed the graphs posted here for the needed light waves. Theirs was just a hair under what is needed for a good water base cure light strength for cross linking.


I’ve experienced one other LED model myself, and I do think it was the Workhorse but can’t tell you what brand it was, other than it was brand new at the time of my Installing an I-Image ST and they bought this one to save money. That would have been 4.5 years ago. The result were fine for solid work, and low lpi. at 45lpi, you could hold the5% dot but not below. It would even be fine at higher lpi, as long as you didn’t introduce any very low percentages into the art. As the LPI got smaller, 55, 65, you could only hold less and less dots. This is an important part for those who are interested in doing sim process and process work at a good LPI such as 55 min. For some shops, this machine would do just fine.  It happened to be that this customer was needing more, and they returned that one and got an M&R LED and are still running that now.


As for undercutting, this is one factor for LED specifically, that is NOT worth mentioning as a contributor or having much impact (when using it to compare to the old experiences we have known from other light sources and the light scatter/undercutting subject). It’s not he same or as much as back when we had this in consideration and a major factor for light sources such as tubes.


There is of course some degradation. There is with all light sources. Just not that much to be considered very impactful with LED. This is for two reasons.


1, The LED lights are much, much closer in distance than a cluster of either LED or a single point MH. For this reason, they are more “direct” than a cluster (grouping of LED lights) or the MH and there is far less “span”or expanse of light source angled out. It’s more “direct” yet true, it’s not 100% totally direct. There is a small amount of scatter. IMO, LED panels, have LESS scatter than MH and a Cluster of LED’s.


2, The small amount of any scatter we do have, is more so a “consistent” scatter, therefore, affecting the entire exposed surface area equally in the same amount across the board. Unlike a central localized light source such as a cluster of LED and even more so obvious with MH as that light source fans out from center. MH is a stronger source, but affects the shapes it is exposing more so, the further you go out from center. Adding to this, is the extended distance factor from the emulsion stencil to the MH light source that increases light scatter. MH is further away, and it is angled out more.

[siestasol]

We have 2 V2536 from CCI, working in tandem with 2 iImage S. No problems for plastisol.
For waterbase or Discharge We use a modified MSP 3140

[3Deep]

My old bulbs in my 5 way went out and many calls I thought it was time to scrap it, but a friend showed me this LED light which is a 100 watt LED point light, I mounted about 16 from the glass and I get great screens in 6 sec with VPR emulsion 20 sec with Ulano orange and I've did some WB/DC using ChromaTech WR emulsion at 45 sec.  The light if I remember correct cost about 100 bucks plus the ballast which I had to rewire my old unit to run it, I've had no problems with screens once I dialed in numbers to burn each emulsion.

[TCT]

We do like 95% WB/DC and use a diazo emulsion. We run a CTS so there is no glass or blanket draw down.

We had the Workhorse one when it first came out. I ended up having a long talk with Tyler I believe, from Workhorse. He flat out said their unit was not designed for WB/DC and he took it back no questions or expense. Stand up move on his part.

We had the first generation Saati single point unit as well, there was a hole in the side of it probably from shipping, but it seemed to function fine. It did not get our screens where they needed to be for a full cure with no breakdown during running.

Our next venture into a LED unit was the Light Speed LED. It has dual spectrum bulbs. It does not get much advertising or hype because the company is smaller. We tried it out because I know the owner and they are based here in MN. So far for us it has been probably 3-4 years and it has been great. Exposure times are much longer(1:20ish) than what I have heard from the Starlight. I personally would not like a 3 second exposure because it does not give you much room for exposure latitude. But it seems to be amazing for most people.

We still have a 5K MH single point unit for more aggressive things like long runs of tote bags, super thick hoodies, or if we do the random run over 5K units.

[Rockers]

We are very happy with our Vastex LED unit. We bought when we were still using film and then made modifications to it after switching to a WAX printer. It`s now mounted  upright to one wall in our darkroom.It serves us very well, produces very good screens and is reasonably fast. Vastex support is as well very good. As a matter of fact almost all our equipment in our darkroom comes from Vastex.

[Maxie]

I use the smaller Saati lamps, they have a bigger one also.
Using PHU I'm very happy with my results.       
This are not a spot lamp but I prefer them to the tables with rows of lamps,
I expose for about 20 sec which I prefer, a slight variation doesn't make much difference.   

[Sbrem]

We use the Saati ProLite 450, and it's working very well for us. We do  mostly plastisol, only the tiniest amount of discharge, so it's fine for us. We do still have our Violux 5K Metal Halide for post exposing the rare times we need to.

Steve

[blue moon]

This would take a very long answer to really touch upon many, many variables in the LED exposure units.
Richard and I tested Starlight when it came out and it had really big field fluctuation. I was told that they sacrificed the uniformity of the field to get a faster exposure time (this is directly from somebody in m&r). I would also imagine that with the number of LEDs in there, there has to be some undercutting, but not sure how much if any. I also know they have (or had few years ago when i talked to them) the good quality LEDs and are cooling and powering them properly.
Vastex had hands down best light field consistency of any unit we tested. It was also using the correct power and cooling. They upgraded the LEDs so I’m guessing those good too.
Saati unit we have is single point light source and has been pretty reliable for us. I am not aware of anything better at this time. We are in 45 second range in exposing our CTS screens (no glass) which is about the same as our msp3140 (1.2kw mh). We use it for wb and dc, but are postexposing to get durability.
I would rate the vastex as 7/10 and the saati 8/10. Starlight would be a 6/10.
A really good 5k mh unit could be 9/10, but the headache that comes with it might not be worth it. It’s like the imagesetter vs film. While imagesetter is better, film does 95% as good with only 20% of the headache. So Saati it is for us.

Pierre

[BrazosDesigns]

Just got in the Saati ProLite 300 kit (300w led box and a countdown timer) to retrofit an existing exposure unit.  I'm set to get it installed in the next week or two and will keep you updated.  I'm thinking of building a custom cabinet for it since Keith Perkins says the top of the led box only needs to be 24" away from the glass to expose up to 25x36" screens. 

This is the first stage in stepping up our game for 2021, along with getting our first set of Matsui inks last month....

[tbarnes]

I'm with Dan, look into single point source UV metal halide units. Definitely the way to go. I don't think I will ever use an LED.

Light is an electromagnetic spectrum and is measured by wavelength in nanometers. LED will hit higher intensities on the spectrum (which allows it to expose in 3-4 seconds) but will cover less of the spectrum as a whole. That is why it doesn't cross link the photopolymers as well as UV lights do.

You are better off baking a cake at a lower temp (intensity) and a longer time to ensure the center of the cake is baked instead of just searing the outsides and leaving the inside gooey. Same rule applies to emulsion and light units.

That being said, if you are a manual shop and printing mostly plastisol, an LED unit is going to be cheaper in the long run and will work just fine for your needs.

[ZooCity]

I don't think there is any LED unit that is superior, in any way besides power draw, to MH and like a lot of other here I would be running MH if I could.  2up screen shooting, perfect detail, thorough exposure... I never found it to be too much of a pain.  Olec units used a shutter v. instant start for good bulb life and low power run when shuttered.   I always used an integrator and light puck to keep everything consistent.  It sounds like you've plugged into the devils power strip when running it and takes a 30a 240v circuit (and it uses that when unshuttered) so it doesn't fit into every screen room like an LED unit will. 

The M&R Starlight unit is a few hundred bucks worth of the right spectrum output LEDs glued to a flexy piece of board.  Pierre, I'm not surprised at all that it's field isn't even since the board is slightly concave as it rests in the unit.   It is far hotter, and takes far longer to expose than our 5k MH.

You can make it work by adapting your coating/screen making technique.  Key to success with the Starlight is to not run screens through it back to back, all day.  If you do that it'll get hotter than 110degF on the outside which is playing with enough heat to start exposing emulsion from the temperature.  (and enough heat to warp your glass...). 

Expos are 70s, 30s, 20s for 150, 225, 330 mesh respectively using a diazo added, high res, water resistant emulsion.   You need to find the sweet spot with your emulsion.  Do not listen to the nonsense about getting 3s expos; you don't want a 3s expo and don't need it if you setup your workflow right. 

Those are some pretty serious downsides, but it plugs into a 110v service outlet and performs every day without failure.   Aside from the weak componentry on the LED side, the unit is typical, overbuilt M&R and comes with their always excellent service and eternal parts availability.   Sim pro work and halftones/detail are "good enough".  That is to say there's a noticeable difference but only to a very trained eye.  At 55lpi, any quality exposure routine should compare well with any other and by the time that halftone becomes ink on a shirt you won't know the difference either.  Our film resolution is much higher than CTS anyways so that's a somewhat hidden advantage if you are using film.

I have our 2 5kw Olec units wrapped up just waiting to be redeployed if we get a power supply upgrade but the reality is that we'll probably move onto laser or dlp before that happens.  Email me if anyone is interested.  Hope the above helps the OP!

[blue moon]

not sure how old is your unit, but about a year  or so after they released it M&R added extra ventilation as it was getting too hot. Maybe rig some better ventilation through the box or see if they will provide you with the parts to modify it yourself.
High temp is a killer for the LEDs and keeping them cool is really important.

pierre