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screen printing => Screen Making => Topic started by: cleveprint on June 22, 2015, 03:21:11 PM
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anyone have a starlight and uses aquasol hvp? starting to mess around with some discharge and wanted to see if anyone had a good idea of for exposure times. for normal plastisol we are right about 7/8 seconds. i figure im going to have to go a little longer. obviously ill test it out, but figure why not ask to get a head start.
Sorry I seem to have messed with your post. Should be all back to normal now Frog
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how are you coating, that will make a difference.
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right now we go 2/2
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sharp or round
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i believe its round. guy that does all our coating is out right now or i would actually ask.
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what mesh count and color, are you adding diazo to the HVP or is it straight?
and do you know what your EOM is?
with pure hvp, 156 white mesh, and 21% eom, we were a 14 seconds for a solid 7 on the stouffer strip during our testing.
21% eom was achieved with round edge, 1 over 1.
with a 1/1 sharp, we were getting around 16% eom.
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Starlight 3140 with the glass
Fixxons/microjet film
Aquasol HVP, no diazo/straight out of bucket
150/48 mesh, yellow
2/1 thin edge coat (do not coat high eom stencils for wb/dc printing, use the thin edge)
25s
We don't run HVP that much anymore but this is what my screen tech had on the chart. Expose your screen as long as it can go without losing detail/undercutting. It's a balance between maxing out the steps on the Stouffer strip and holding the minimum detail you need on that mesh. Disregard any comments about shooting screens in 0.5-7s etc. with the Starlight, at least with glass/film and especially with discharge printing- you want your screens strong, not just imaged.
*EDIT- probably none of us have a device to measure dmin/max but it makes a difference, especially when using a less collimated light source. Assuming we're all using similar dmin "waterproof" film. For dmax reference I'll say our positives when held up to a bright light, block it out completely, i.e. you can't see the bulb. If your positives are more like looking through darker sunglasses you may not be able to burn as long.
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Starlight 3140 with the glass
Fixxons/microjet film
Aquasol HVP, no diazo/straight out of bucket
150/48 mesh, yellow
2/1 thin edge coat (do not coat high eom stencils for wb/dc printing, use the thin edge)
25s
We don't run HVP that much anymore but this is what my screen tech had on the chart. Expose your screen as long as it can go without losing detail/undercutting. It's a balance between maxing out the steps on the Stouffer strip and holding the minimum detail you need on that mesh. Disregard any comments about shooting screens in 0.5-7s etc. with the Starlight, at least with glass/film and especially with discharge printing- you want your screens strong, not just imaged.
*EDIT- probably none of us have a device to measure dmin/max but it makes a difference, especially when using a less collimated light source. Assuming we're all using similar dmin "waterproof" film. For dmax reference I'll say our positives when held up to a bright light, block it out completely, i.e. you can't see the bulb. If your positives are more like looking through darker sunglasses you may not be able to burn as long.
Changed that to bold red text, sort of important info
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25s??
I don't know what you meant by that.
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25s??
I don't know what you meant by that.
25 seconds? Remember he also said to disregard those short times of 5-7 seconds.
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The starlight runs on seconds, not ltu, there's no integrator.
Good call Orion, not knowing that (I sure didn't when I first started doing wb/dc) could make it nigh impossible to get a successful waterbased print.
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I'm super interested in getting a starlight, and even tested one internally.
We would run without glass (Spyder II DTS), and were previously using Kiwo Versa-TEX with Diazo. In testing in house, it took 80 seconds to properly expose the screen.
We are switching emulsion to the new version Kiwo Multi-TEX which doesn't need Diazo, and should get a faster exposure time. I'm tentative to buy a Starlight since unless I can get the exposure time to around 30-40 seconds, I'm better off just using my 5K MH and doing 5 at a time.
Anyone have a starlight and use Kiwo Multi-TEX, and can post their real times. I feel like possibly the times posted would be considered well underexposed at our shop, which could be leading to some of the other threads in this forum where people have issues reclaiming.
I love the idea of a starlight, but hitting anywhere near the 7-10 seconds people claim, just seems so far fetched to me and what I have seen in testing within my environment. Love the idea, and would love for it to work, just tentative.
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Do you really want 7 seconds tho? Your exposure latitude would be less than. 1/2 a second....
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Do you really want 7 seconds tho? Your exposure latitude would be less than. 1/2 a second....
If that was directed at me, yes I would really want 7 seconds if it fully exposed a screen :)
But I'm realistic, and if I could get the exposure time down to 30-40 seconds realistically, with a fully exposed screen, then I would get a starlight. In testing it took 80-90 with a different emulsion.
I know I will never see 7, or even 12 seconds with the emulsion we use, but 30-40 seconds would be fast enough that it would make sense to purchase as we could expose one screen while the CTS is printing another, and keep a constant waterwheel rather than doing 5, moving them to the light.
But we sway to the side of maybe what some shops would call over exposing.
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Zane: I agree on all your points ;)
Exposing a screen as fast as the DTS can spit them out is fast enough for me.
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If you need/want speed, stick with 5k MH. If the Starlight could shoot 2up it would be more of a contender to replace MH in the speed category but still slower. Or you could buy two or more Starlights....
In any case this discussion of speed isn't a knock on the Starlight, my understanding is it was not designed for speed. The main benefit we see is lower power consumption and small footprint.
You can actually get a 7s expo time with HVP, with glass and film, with a good 5kw positioned to shoot 1up.
But even with DTS those super fast times with the Starlight are either extremely fast shooting emulsions or people just aren't fully exposing, which is fine for some all plastisol shops, no go for the rest of us. When some manufacturer matches an emulsion to the Starlight's LED spectral output the times have the potential to get quite fast.
M&R will test your emulsion for you. Give them a call. They emulated one of our screens- same mesh, emulsion, amount of diazo, right down to the same scoop coater I believe so we could double check the times against each other.
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Zane: I agree on all your points ;)
Exposing a screen as fast as the DTS can spit them out is fast enough for me.
That's a great point. If the expo unit keeps up with your positive output, that's all that should be needed regarding speed.
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I have a starlight and don't change any of my times for discharge screens. I also have a similar emulsion (CCI). I do post expose my discharge screens though.
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sorry for not getting back right away, we lost phone and internet last night and its just getting back on today. thanks for the starting info. as i said, i will test for sure, but its always nice to have a starting point. as far as the 7/8 seconds for regular plastisol, we do not seem to run into any issues there. they might not be fully exposed, but very rarely do we get breakdowns.
im going to give it a go in the 14-15 second range and go from there. i might as well post expose too, probably cant hurt.
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To reinforce the thread here. Yes 1:1 coat thick edge or 1:2 thin edge is all you need to get good EOM with Aquasol HVP. With fast exposing systems like the Starlight there is such a thing as too fast. Image vs Exposure, both can make a print, one will outlast the other on press. Bake the Cake! No baker has ever said, lets try baking bread in half the time today, the inside would be a gooey disaster, same with emulsion where cross linking is incomplete it will soften and break down. It's what you can't see that matters. With waterbase you want the squeegee side well exposed. Fast exposures can prevent the squeegee side from proper exposure where mechanical abrasion with discharge and wb can wear away the emulsion quickly. As mentioned, the goal is to find a balance between complete exposure and getting details out. The MH vs Starlight has been discussed a lot here. Both work, just have to fine tune the times and the coating technique. Resolution, durability and all play a part.
Alan