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screen printing => Screen Making => Topic started by: ericheartsu on March 01, 2013, 11:16:43 AM

Title: non stop pin holes
Post by: ericheartsu on March 01, 2013, 11:16:43 AM: I'm having a problem where my graphics screens are getting CRAZY amounts of pin holes all over them.

None of my textile screens have this problem. All the screens are washed and dried the same. Coated in the same room, sit in the same room. Only difference is my Textile screens use Kiwo Discharge, and my graphics screen use Kiwo Poly Plus S emulsion.

Textile screens get coated 2/1 for discharge, and 3/2 for plastisol. Graphic screens get 2/1.

Any ideas on what i'm missing?
Title: Re: non stop pin holes
Post by: Inkworks on March 01, 2013, 11:27:38 AM: Is it the first use of the screens with new mesh? Sometimes I find that the emulsion doesn't stick as well the first use of new mesh even if you de-haze/degrease prior to coating.
Title: Re: non stop pin holes
Post by: Frog on March 01, 2013, 11:39:22 AM: Quote from: Inkworks on March 01, 2013, 11:27:38 AM
Is it the first use of the screens with new mesh? Sometimes I find that the emulsion doesn't stick as well the first use of new mesh even if you de-haze/degrease prior to coating.

That tends to lead more to "fisheye" rather than pinholes. A slight resist due to oils on the screen (even from something seemingly benign like fingers)
Pinholes are generally dust. They either wash out, or break through during the printing process.

Eric, could the emulsion itself possibly be contaminated?
Title: Re: non stop pin holes
Post by: ericheartsu on March 01, 2013, 12:55:21 PM: Quote from: Frog on March 01, 2013, 11:39:22 AM

Eric, could the emulsion itself possibly be contaminated?

This was actually my next step. I was thinking this as well.

but also apon further inspection of the mesh, it seems that there seems to be tiny specs of emulsion dried onto the mesh, that we cannot get out. We've had issues with sand in the past, but this doesn't look or feel like sand. I noticed this right after stripping a screen, dehazing, then degreasing throughly.
Title: Re: non stop pin holes
Post by: ScreenFoo on March 01, 2013, 02:17:54 PM: Boy, if you have problems with emulsion washing away where it shouldn't, AND you're having problems with it NOT washing out... that's rough.

+1 trying another batch of emulsion...
Title: Re: non stop pin holes
Post by: ebscreen on March 01, 2013, 02:33:41 PM: Yep, we've seen what you are describing on bad emulsion, particularly when you get to the bottom of the bucket.
Switched back to Aquasol, problem solved.
Title: Re: non stop pin holes
Post by: ZooCity on March 01, 2013, 02:47:26 PM: Give those screens a serious dehazing and see if that solves it.
Title: Re: non stop pin holes
Post by: ebscreen on March 01, 2013, 02:53:39 PM: We've also seen weird black dots show up on clean screens. New pressure washer gun, problem solved.
Gotta watch these things.
Title: Re: non stop pin holes
Post by: ericheartsu on March 01, 2013, 03:54:04 PM: After some conversations with some vendors, i think it may be some expired diazo. grabbing a new batch of emulsion today.