Exposure Times 38 mesh glitter PLEASE HELP

[bdizzle009]

Hey guys new to the forum would love some advice on something I've been struggling with.  I've found its tough to find alot of info on glitter screens because alot of people don't even bother with it but I just thought Id ask.  I'm having problems with exposure.  Whether I lower the exposure time or raise it I can't find a happy medium, up the exposure and the image doesn't wash out, lower it and the emulsion peels off during wash out any suggestions? Using Prochem DCM emulsion and a ryonet rxp 25x36 lightbox.  Thanks.

[Screen Dan]

What's the ballpark for more reasonable meshes?  150/48, 180/54, 230/48, etc...?  How do you coat?  Which side of the coater?  How many coats on each side?

I'm not familiar with that emulsion but if it's not an extra high solids content emulsion you'll probably be plugging pinholes constantly.  Phat Films are another option...though I personally love Aquasol HS for this.  You can just straight up coat it and run it, or you can coat it, dry it and make a build up on the face for HD prints, stacking, etc.  I think the fact that this emulsion is so opaque gives us more exposure latitude, but I could be wrong.

For example, we use Aquasol HS, we coat our 38s (and 25s) 4 on print side, 4 on squeege side, on the rounded side of the coater.  This usually gives us a ~150 to 200µ coat.  Nothing crazy, but a far cry from your average color plate.  We expose this for ~240 seconds on a 5k MH exposure unit.  These numbers are for relative reference only...yours will be far different.  For reference, our 150/48 screens coated 1/2 (with the sharp side) expose for about 80 seconds...(when the bulb is brand new it's 60).  Our 225/48 expose for 40 currently (32 with a new bulb).

Now comes the tricky part...You don't just spray that out.  We soak it in the dip tank for 20-30 minutes.  Then we spray it, slowly....delicately, until you start to see the image develop.  Then you'll know where to attack with more intensity and where to be more delicate.  Or we expose it for ~300s and hit it with the monster pressure washer we use for destenciling.

Bottom line is if you are peeling the emulsion off it's definitely not exposed enough.  If it is a high solids emulsion then once it is exposed enough it's still a relative nightmare to develop compared to other screens.  Our developing pressure washer is 1900 PSI with 2.5gpm...our destenciler is 3000 PSI, 3.5gpm.  I don't think it would be possible to develop this with a garden hose like you can with a regular screen.  If you are in there for a half hour and completely soaked by time it's finished?  That's normal.  That means it worked.  You can tweak details from that point.

[Ross_S]

Well if your printing glitter your going to need a 40 mesh screen.  How long are you exposing your 110's?  Take that time and then add about 25% more time to it and start there.

[Colin]

mkay...

The exposure unit you are using has no vacuum on it, so are you sure you have NO light leakage onto your screen from outside sources?  Are you sure that you have a very tight connection between your film positive and your screen, the pad is giving good pressure?

How much detail is in your design/film for the glitter screen?  Really low mesh counts hold almost no real detail, this could be part of your issue.

The exposure unit you have is also either blacklight or uv tubes.  These types of units are notorious for loosing allll kinds of details.  They are also weak in terms of being able to punch through thicker layers of emulsion, making lower mesh counts difficult to expose properly. There are technical reasons for this, but we can save that for later posts.

I think an excellent start for good solid advice would be to post a pic of the film and design you are trying to print and we can give our feedback as to how we think we can make it work in your shop with your setup.

oh, also, did you coat the 38 mesh differently than your other screens that you have no problems exposing?

[mk162]

my guess is the DMAX on your film is weak.  You will really struggle with properly exposing emulsion and still being able to rinse out the image area if you films aren't dark enough.

[Screen Dan]

Good point.  I'm over here in my DTS bubble.

Stack films?  So many complications.  Would probably undercut, registration might be hard to get, films eat light...oof.

[Grumpy Ole Artist]

At least you are using film, and NOT stuck in vellum hell! You can stack multiple copies of a film positive to up your density, with no harm done to background...I STRONGLY discourage clients from using glitter...My vellum density is so poor here, The last time I HAD to do it, despite running them through the dryer, AND using toner aid,  it took 3 tries before I got a useable image...the longer exposure gives the light more time to burn through the Gray (not Black) toner

[tonypep]

Well if your printing glitter your going to need a 40 mesh screen.  How long are you exposing your 110's?  Take that time and then add about 25% more time to it and start there.

38/40 mesh= same results

[ScreenFoo]

I bet MK nailed it.
You could always expose a 305 mesh backwards with the art, and then print the art on the back of the 38 mesh stencil to expose/develop. 

It'd be a pain, but your Dmax would be great--with a 0 Dmin to boot!

(At least half kidding)

[jvanick]

depending on the art, you could always cut some rubylith or maybe even black cast vinyl on a vinyl plotter as well...

I used to do that before we had an all-black setup for our epson printer... the longer exposure times for the glitter screens would kill us.

-J

[ABuffington]

As mentioned, your film may not have enough dmax or opacity.  Stack them.  A 40 mesh thickness is 377 microns, a 110 is 134 microns.  As also mentioned Aquasol HS is an emulsion that can build up to form a good ink well and print gasket.  So add 200 microns to the 377 and 577 microns is a little over 4 times as thick.  So a far longer exposure is needed which requires good black opaque images since your exposure can be over 30 minutes on fluorescents and about 7-9 minutes on a 5k metal halide using a pure photopolymer like Aquasol HS. Typically on a 5k metal halide you need 1.5 minutes per 100 microns.  Fluorescents and LED comes in so many flavors that you should perform a step test to determine your times. 

Step Test Instructions:
http://murakamiscreen.com/wp-content/uploads/2012/07/Step-Test-Instructions.pdf


Alan

[Frog]

What the hell, though usually only visiting for punitive purposes, our illuminating friend hasn't popped in for a while