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out da box · July 16th, 2009

Yesterday we printed 1300pcs in 3 hours. From 3 pm till six.
Granted it was a 1 color.

Today with all hands on deck and then some, we only did 2000.
It was a 7 color and everyone of them gave me problems. Most were my fault with burning the image too high up on the screens- design has awkward placement.
The pinholes and stencil breakdown is killing me. Had to reburn 3 screens out of 7. At different times! I don't think I'm gonna use the pressure washer to wash out and I think I'm gonna have to use 40-45lpi dots on my 230's. That way I can expose a touch longer and hopefully make them more durable. The dang photopolymer emulsion just burns so fast.... first time I've had this issue with this latest emulsion. First time we did over 500 with it though.

Live and learn.
Non- ideal set-up is a serious, serious time killer and production killer on an auto.

wiggle · July 16th, 2009

Rather than burning longer, why don't you post-expose. When you get done washing out your image, throw it back in the exposure unit for the same amount of time you burned it at and you harden up the emulsion.

Uncle John · July 16th, 2009

Ridgely, it sounds to me it's a humidity problem. If you pressure wash the same, it should work. John

amp267 · July 16th, 2009

you use a pressure washer to wash them off. seems a bit extreme or im i missing something. i do something similar to what was stated above, after wash out i put them in the sun to dry and harden up

vipgraphx · July 16th, 2009

I use a pressure washer as well...first on low then I let it sit and pressure wash from a good distance. Then post harden in the sun. I prefer the sun because its free energy and saves my life span of my lights.

amp267 · July 16th, 2009

Quote:

Originally Posted by vipgraphx


	I use a pressure washer as well...first on low then I let it sit and pressure wash from a good distance. Then post harden in the sun. I prefer the sun because its free energy and saves my life span of my lights.

i guess your right, i have used it one time from a distance to blow out some tuff spots, rarley though.

Fluid · July 16th, 2009

Quote:

Originally Posted by out da box


	! I don't think I'm gonna use the pressure washer to wash out and I think I'm gonna have to use 40-45lpi dots on my 230's. That way I can expose a touch longer and hopefully make them more durable.

after you burn and wash out the image, burn the screen again or set in the sun for a bit. screens seem to last a bit longer.

out da box · July 17th, 2009

I do put them in the sun. Still getting pinholes. Squeegies set to 50-75psi. Not a ton of pinholes like with dual cure, but still. Main issue is stencil breakdown after hundreds of prints.
Also we use a dehumidifier.

JeridHill · July 17th, 2009

How do you coat your screens? On an auto, I find it's better to do 2/1, then dry, then 1/1. Where the 2/1 is pretty much scraping off excess emulsion after you coated both sides once.

out da box · July 17th, 2009

I do 2/2 with the round side. I've tried face coating, but I have trouble exposing correctly with the extra thickness. I think my light is too close- 24" 400 watt m-h bulb.
I really think I didn't expose quite long enough, I wanted to hold 50lpi halftones on 230's.

JeridHill · July 17th, 2009

I agree it can be somewhat problematic to get the right exposure times and of course it depends on screens as well as the exposing mechanism. Either way, if you add say 30 seconds, you might hit it right the first time. Either way, I've played around with it enough to realize doing another coat after it dries will eliminate the issue of pinholes every single time so as long as the screen is prepped right.

out da box · July 17th, 2009

Well thing is my time is so fast, there's no room for wiggle- 25sec

alan802 · July 17th, 2009

A 2/2 should be good as long as the solids content is at least in the mid 40's. I've never had a stencil break down from printing production in 3+ years. We use a photopolymer that must be tough as nails and has a 50% solids content.

When I first read I suspected too thin of a coat job but it must be something else. I've worn through the stencil from using too much pressure and squeegee blades having sharp corners but never had the emulsion wear down.

Holding 50lpi on 230 is doable as long as you've got everything dialed in. We deal with pinholes in mesh counts over 175 but the stencil is so much thinner and the work environment is not dust free.

Solmu · July 18th, 2009

Quote:

Originally Posted by out da box


	I really think I didn't expose quite long enough

You know what Greaves would say to that

(measure measure measure)

out da box · July 18th, 2009

Yeah, I have used an exposure calculator on this mesh and with this emulsion and it came out to 25 sec, but actually could be a little less- according to the calculator- autotype.

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