Printech Archive, April, 1999: Re: Chromate in Screen Emulsion

Re: Chromate in Screen Emulsion

Michael R. Ukena (
Thu, 1 Apr 1999 22:07:17 -0800

I am quite curious about the chromate problem. Many years ago, screen
emulsions were sensitized with bichromate. This was eliminated at the
industrial level more than ten years ago because it was determined that the
use of bichromate created serious health risks including cancers.

Modern emulsions come in three types: Photopoloymers, dual-cures, and
diazo-sensitized. None of these types have any measurable amounts of

However, I do know that there is no prohibition (which shocked me) against
selling bichromate sensitized emulsions for craft use. When I was at the
SGIA a school teacher sent us some bichromate emulsion to see if it was any
good. We were shocked and investigated the source. It turns out it is
legal for craft purposes.

It is my opinion, that the only way this company could get bichromate
emulsions in industrial quantities is from an offshore source. And, the
cure to the bichromate problem is to cease using this type of emulsion and
buy from a reputable U.S. source that has approved emulsions available.

I know many printers (including my own shop) that have had their screen dept
effluents checked, and chromates and chromium were never an issue. They
weren't even found in minute amounts.

Hope this helps.

Mike Ukena

-----Original Message-----
[]On Behalf Of Wayne Pferdehirt
Sent: Thursday, April 01, 1999 7:57 AM
Subject: Re: Chromate in Screen Emulsion

I am forwarding this question to the Printech listserv from the ChemAlliance
listserv. Any ideas we can pass along re. reduction or control of the
chromate? Post responses to Printech and I will forward for posting to

> >From: []
> >Sent: Thursday, April 01, 1999 9:02 AM
> >To: ChemAlliance Regulatory Discussion List
> >Subject: [chemalliance] Chromate
> >
> >
> >I was wondering if anyone might be able to help me out. We have a
> >division of
> >our company that makes screens for another division of our company that
> >does the printing. The division that makes the screens is having a
> >problem with high chromium numbers. This is being caused by washing the
> >emulsions of off the screen so that they can be reused. The
> >chromium(actually chromate) is coming from the emulsion on the screens.
> >Does anyone have any suggestions in eliminating this problem. We know
> >would could precipitate it out with SO2, but we were wondering if there
> >was another way, other rhan chemical treatment. Thank you very much.
> >
> >Mike

Wayne P. Pferdehirt, P.E., AICP
Director, Master of Engineering in Professional Practice Program
Specialist, Solid & Hazardous Waste Education Center
University of Wisconsin-Madison/Extension
610 Langdon Street, Room 532, Madison, WI 53703-1195
Phone: 608/265-2361 Fax: 608/262-6250



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