Vastex 2000 LED exposure unit teaser

[Denis Kolar]

OK, those throwing with numbers of 3, 5, 10, 12 seconds made me think a bit.
Is there really an advantage of having a exposure unit that will save you 4 seconds per screen, even if you are making 100 of screens per day?
That is 400 seconds which is less that 7 minutes per day if you do 100 screen per day, and there is only a few of people here that do that regularly. (Maybe)

My biggest concern is a margin of error in the 3 or 5 seconds exposure time.
I have Nuarc 40-1K and takes me about 80 seconds to expose a screen. I expose one, wet it, get the new screen out and put it in exposure unit, wet the first one again, start exposure, wet the first one again, wait a bit, wash out. By the time I wash out the first one, second one is exposed. Even if I mess up a bit with exposure times, i'm still OK with slightly overexposed screen.

But if you overexpose a screen with this unit by a .25 of the second, you are screwed. And, after 4-5 minutes you will have 20 screens exposed and none of them will be washed out, or if you have two people working, you might have 3-4 washed out by the time you expose 20.

I would like to have better exposure unit, and maybe expose the screens in 30 seconds, but to me, I do not see the benefit of exposing a screen that fast. I understand a benefit of saving time exposing, but unless you can was out that fast, what is the benefit? Except maybe say that you have a machine that can expose a screen in 3 seconds.

Just thinking out loud

[ScreenPrinter123]

There is no real way to test this unit without running a long DC job on them when we're finished exposing them for 5 seconds or whatever the time is because I've seen it so many times, a screen looks fully developed and shows no signs of underexposure until you're 50 shirts into a DC print.

BINGO!

[ZooCity]

Alan is correct, the time needs to be longer.  Richard Greaves spoke with me at length once regarding this.  Fast is good for production in some situations but not optimal for the strongest stencil.  I think the ideal is a speed that gives the flood of UV light adequate time to penetrate through the stencil but not so long that undercutting begins to effect fine detail. 

DK, to answer your question I feel that you can always setup a screen area to allow someone to do another task while exposure is going on- aligning film, etc.  So expo time to me is more a function of getting the perfect screen, not speed of exposure

Now, if one were to develop an emulsion specifically for a certain LED spectral output you may be able to change this and rip out quality exposures at 3sec but DK is correct in that your margin of error will be very unforgiving here.  I say that a 12-24s expo is plenty fast for a 1up unit.

Also, we're all comparing expo times using halide bulbs which are placed much further away from the screen.  Our unit's shutter is optimal at about 64", for example.  If we had a bank of tiny little halide outputting devices sitting inches away from our glass that would obviously change a lot of expo values.  Inverse square law or some business like that. 

[244]

OK, those throwing with numbers of 3, 5, 10, 12 seconds made me think a bit.
Is there really an advantage of having a exposure unit that will save you 4 seconds per screen, even if you are making 100 of screens per day?
That is 400 seconds which is less that 7 minutes per day if you do 100 screen per day, and there is only a few of people here that do that regularly. (Maybe)

My biggest concern is a margin of error in the 3 or 5 seconds exposure time.
I have Nuarc 40-1K and takes me about 80 seconds to expose a screen. I expose one, wet it, get the new screen out and put it in exposure unit, wet the first one again, start exposure, wet the first one again, wait a bit, wash out. By the time I wash out the first one, second one is exposed. Even if I mess up a bit with exposure times, i'm still OK with slightly overexposed screen.

But if you overexpose a screen with this unit by a .25 of the second, you are screwed. And, after 4-5 minutes you will have 20 screens exposed and none of them will be washed out, or if you have two people working, you might have 3-4 washed out by the time you expose 20.

I would like to have better exposure unit, and maybe expose the screens in 30 seconds, but to me, I do not see the benefit of exposing a screen that fast. I understand a benefit of saving time exposing, but unless you can was out that fast, what is the benefit? Except maybe say that you have a machine that can expose a screen in 3 seconds.

Just thinking out loud

Come to the show and see. There will be a developer there washing out the screens as well. No need to have a person doing it with the Econo-Rinse unit. Seeing is believing and we are running the screens with no break down yet!

[ZooCity]

Rich, did you guys build a standalone, contained pressure washing unit?  I've always thought that would be perfect to have a couple of those in the wet room instead of blasting water and chem vapor everywhere with a press washer. 

[244]

Rich, did you guys build a standalone, contained pressure washing unit?  I've always thought that would be perfect to have a couple of those in the wet room instead of blasting water and chem vapor everywhere with a press washer.

Yes we did. The unit will be on display at the SGAI show.

[ZooCity]

Excellent. One of your boys is stopping by tomorrow, I'll be sure to request some pricing.

[244]

Excellent. One of your boys is stopping by tomorrow, I'll be sure to request some pricing.

Pricing and information to the regional wont be ready until the day before the show. Still pricing the BOM.

[alan802]

I just got through developing and analyzing the 5 screens I burned with the Vastex unit.  I know this won't matter to a good many of us but this is what I did with what I had.  HVP, pure photopolymer without the diazo added to it.  We've found the HVP to burn almost exactly like all the other PP's that we've tried.  These were all coated with the glisten method and had around 15-20% EOMR.  I can get exact emulsion thickness numbers if anyone really wants them but just know these screens weren't thick by any means, but they weren't the bare minimum stencil either.  I did the 305 at 10 seconds, 230 at 15, 195 at 15, 156 at 20 and the 110 at 30 seconds.  The 156 and 110 were noticeably underexposed.  The 305 sprayed out nicely and showed no signs of underexposure and the 230 and 195 also came out looking great.  Our bulb is older now and when it's new, a light unit is about 5-6 seconds, now it's about 12-15 seconds per unit so when comparing exposure times with an aged bulb, the LED is significantly faster. 

Now for the quality and stencil edges:  I don't know if I'm just tired and couldn't get into looking through a loupe for an hour but I couldn't find any blemishes on the LED screens.  Besides the usual underexposure problems that you see, there was really no difference between the 305 I burned with the MH unit versus the LED.  They both looked fanstastic and held the same percentage dot and the edges were as crisp from screen to screen.  I will look at these again in the morning to see if I find anything of significance on the LED screens but I don't think I'm gonna find anything that will matter to any of us, even those guys who are entering competitions.

So I guess I'll eat some crow.  After my first test, I didn't think the LED would perform as good as a 5K and up MH bulb, but after these 5 screens, I am proven WRONG.  More to come later as I think of it or if anyone has any questions on my little testing session today.  I'll also look at the screens again in the morning with a fresh mind.

[Nation03]

Other than the fast exposure times I thought the main benefit from the LED units is the fact that you would rarely, if ever, have to change the bulbs. I think what is appealing also, is that you can get close to a MH quality exposure in a smaller, tabletop unit. I know that isn't right for everyone, but for a smaller shop that isn't going to expose screens larger than 23x31, this type of unit will be ideal. If I'm in a space constraint, having a smaller exposure unit without sacrificing screen quality is a home run.

[JBLUE]

I just got through developing and analyzing the 5 screens I burned with the Vastex unit.  I know this won't matter to a good many of us but this is what I did with what I had.  HVP, pure photopolymer without the diazo added to it.  We've found the HVP to burn almost exactly like all the other PP's that we've tried.  These were all coated with the glisten method and had around 15-20% EOMR.  I can get exact emulsion thickness numbers if anyone really wants them but just know these screens weren't thick by any means, but they weren't the bare minimum stencil either.  I did the 305 at 10 seconds, 230 at 15, 195 at 15, 156 at 20 and the 110 at 30 seconds.  The 156 and 110 were noticeably underexposed.  The 305 sprayed out nicely and showed no signs of underexposure and the 230 and 195 also came out looking great.  Our bulb is older now and when it's new, a light unit is about 5-6 seconds, now it's about 12-15 seconds per unit so when comparing exposure times with an aged bulb, the LED is significantly faster. 

Now for the quality and stencil edges:  I don't know if I'm just tired and couldn't get into looking through a loupe for an hour but I couldn't find any blemishes on the LED screens.  Besides the usual underexposure problems that you see, there was really no difference between the 305 I burned with the MH unit versus the LED.  They both looked fanstastic and held the same percentage dot and the edges were as crisp from screen to screen.  I will look at these again in the morning to see if I find anything of significance on the LED screens but I don't think I'm gonna find anything that will matter to any of us, even those guys who are entering competitions.

So I guess I'll eat some crow.  After my first test, I didn't think the LED would perform as good as a 5K and up MH bulb, but after these 5 screens, I am proven WRONG.  More to come later as I think of it or if anyone has any questions on my little testing session today.  I'll also look at the screens again in the morning with a fresh mind.

Can you expose some linearized 55 and 65 lpi screen halftone screens? I am waiting for someone to share that info.......

[Shanarchy]

Pierre, if someone had a MH unit (msp3140) do you think they would see enough advantages going LED to make it worth it? I've been tempted to upgrade my old fluorescent unit (Nuarc first light).

Rich, will M&R also have an upgrade kit for fluorescent units?

[244]

Pierre, if someone had a MH unit (msp3140) do you think they would see enough advantages going LED to make it worth it? I've been tempted to upgrade my old fluorescent unit (Nuarc first light).

Rich, will M&R also have an upgrade kit for fluorescent units?

you would be better off with new. Cost would be less.

[inkstain]

Just sharing.

I've had my Baby Joe 2000 for a bunch of months now and it's been awesome!
And even in Humidityville Hawaii, it's been handling great.  Not sure how much changed when Vastex and the man who made the Baby Joe.  Did it change much Pierre?
Any way, I was flourescent bulb guy for years upon years.  Here in Hawaii it would take me a good 3:30 to expose a 156 screen.  Now it takes me 30 seconds and it holds really good detail.  I know that if I was back in California where it was really dry, exposure time would be faster. 

Like I said.  Just sharing.

Stoked I went LED.

[alan802]

I just got through developing and analyzing the 5 screens I burned with the Vastex unit.  I know this won't matter to a good many of us but this is what I did with what I had.  HVP, pure photopolymer without the diazo added to it.  We've found the HVP to burn almost exactly like all the other PP's that we've tried.  These were all coated with the glisten method and had around 15-20% EOMR.  I can get exact emulsion thickness numbers if anyone really wants them but just know these screens weren't thick by any means, but they weren't the bare minimum stencil either.  I did the 305 at 10 seconds, 230 at 15, 195 at 15, 156 at 20 and the 110 at 30 seconds.  The 156 and 110 were noticeably underexposed.  The 305 sprayed out nicely and showed no signs of underexposure and the 230 and 195 also came out looking great.  Our bulb is older now and when it's new, a light unit is about 5-6 seconds, now it's about 12-15 seconds per unit so when comparing exposure times with an aged bulb, the LED is significantly faster. 

Now for the quality and stencil edges:  I don't know if I'm just tired and couldn't get into looking through a loupe for an hour but I couldn't find any blemishes on the LED screens.  Besides the usual underexposure problems that you see, there was really no difference between the 305 I burned with the MH unit versus the LED.  They both looked fanstastic and held the same percentage dot and the edges were as crisp from screen to screen.  I will look at these again in the morning to see if I find anything of significance on the LED screens but I don't think I'm gonna find anything that will matter to any of us, even those guys who are entering competitions.

So I guess I'll eat some crow.  After my first test, I didn't think the LED would perform as good as a 5K and up MH bulb, but after these 5 screens, I am proven WRONG.  More to come later as I think of it or if anyone has any questions on my little testing session today.  I'll also look at the screens again in the morning with a fresh mind.

Can you expose some linearized 55 and 65 lpi screen halftone screens? I am waiting for someone to share that info.......

The exposure calculator has 65, 85 and 105 line halftones from 0-100%.  The LED held the same dot as the MH unit.  On the 65 line it held the 5% down to the 97% coverage hafltones, I didn't really look at the 85 and 105's because those dots are way too small for a 305 in my opinion.  I did hold them in probably the 9%-82% range on the 85 line row but I don't remember at all what the 105 looked like, I rarely pay much attention to that row because if my guy outputs anything at 105 I'm gonna put a boot in his rear.