screen printing > Equipment

Exposure Units

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adman1986:
Wondering if someone could tell me the difference in screen quality outcomes when it comes to using a Amerigraph or Nuarc metal-halide vs a Vastex E-2331 multi light source. I know where I worked before we had a Nuarc 3140 because of all the half tones screens we were shooting. I am making my equipment purchases and don't want to make the wrong choice. Brandt you may be able to answer this question since I noticed you had both in your pics of your shop.

Denis Kolar:
I do not have much experience, but from my research when I was buying, I have learned that if you think about printing halftones buy the single point exposure. With multi light exposure, you will have lights coming at multiple angles to light up a single dot which will result in undercutting on stencil.
I ended up with a used single point Nuarc 40-1K with a Mercury bulb for $350. Not as good as MH exposure units, but it does pretty good work with halftones.

Orion:
Agree with DK, single point light source.

ZooCity:
+1 for a single point light source.

Aside from good 'ol sunshine in the very early days, single point is all I've used.  And I've used everything from a low-bay warehouse MH lamp to the Olec we run now, all of it homebrewed and jerry rigged to some degree and have been quite happy with our exposures pretty much all the way.

Off the top of my head, three things you really want in an expo unit:

* Vacuum top
* Single point light source
* Integrator
You don't absolutely need any of that but if you want to really move through the screens, resolve fine lines and halftones with confidence and not have a high rate of failure I would start there.  I would never go without these in a production environment again.

I also like a shuttered bulb rather than an "instant-on" type, it seems to extend bulb life.  And, I don't really see the point (oh ho! accidental pun!) in blacklight units that are built so well mechanically but are still using diffuse, UV-weak light to do the exposin'.  Nevertheless, printers expose great screens, halftones and all on them every day I'm sure.   Last thing I'll say is get a 5k watt unit if you can swing it, even more is better.  It's less about having 10 second exposures (which we do with our 5k and that's certainly nice) and more about getting a solid exposure all the way through the stencil.  The extra watts seem to really help out in that department but I find a post exposure to be necessary on any of our thicker stencils and anything destined for waterbased ink. 

Hope that helps.  There's probably a whole slew of articles on this out there in the interwebs. 

adman1986:
Thanks for the replies guys

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