Printech Archive, April, 1999: Re: Retention factors in screen printing

Re: Retention factors in screen printing

DAVE SALMAN (SALMAN.DAVE@EPAMAIL.EPA.GOV)
Mon, 05 Apr 1999 09:15:44 -0400

Deb -

I agree with your response on screen printing on plastic, but I have
something to add with regard to solvent retention in shop towels
and to some of the "additional information" you provided particulalry
in regard to lithography.

I agree that it is unlikely that there would be any significant retention
of solvent (VOC) when screen printing on plastic cards. In fact, I
have never heard any claim or discussion about any solvent (VOC)
retention from inks or coatings used in any type of screen printing.

There are two items I would add about cleaning solvent retention in
shop towels. First, US EPA has thus far only recommended use of
the 50 percent retention factor for cleaning solvents in shop towels
for offset lithographic printing. This is discussed in the June 1994
ACT for offset lithography and in the April 14, 1998 Potential to Emit
Guidance for Specific Source Categories. Second, US EPA has
also tied the 50 percent retention factor for offset lithography to using
cleaning solvents with a vapor pressure less than 10mm Hg at 20
degrees C. The question of broadening the applicability of the 50
percent retention factor to other types of printing has come up in the
testing issues subgroup of the Pollution Preventing in Permitting
Project (P4) for printing. I think we are headed in the direction of
broadening the guidance, but we have not done it yet.

In regard to solvent (VOC) retention from inks or coatings used in
other types of printing, EPA has provided definitive guidance
with regard to ink oil (VOC) retention for offset lithography.
The guidance being that a 95 percent retention factor is appropriate
for non-heatset offset lithography and a 20 percent retention factor is
appropriate for heatset offset lithography. [Note: These factor are for
the use of (petroleum and vegetable) oil based materials where the
VOC content is determined by EPA Method 24. There is no
retention factor for uv cured litho inks.] This guidance is provided in
the September 1993 draft CTG. None of the comments submitted to
EPA on the draft CTG addressed this topic, so there is no
discussion of this topic in the ACT document which is essentially a
discussion of and response to comments made on the draft CTG.
The same guidance is provided in the April 14, 1998 Potential to
Emit Guidance for Specific Source Categories. My understanding
is that most states are accepting and following this guidance for
offset lithography. The ACT document also provides heatset litho
dryer carry over factors for alcohol substitutes in fountain solution
(70 percent) and low vapor pressure (less than 10mm Hg at 20
degrees C) automatic blanket wash materials (40 percent). Most
states are accepting and following this guidance as well.

Dave Salman
US EPA
Office of Air Quality Planning and Standards

>>> Deb Kramer <dkramer@wmrc.hazard.uiuc.edu> 04/02/99
08:13am >>>

The following question was posted from the PNEAC web site. Any
responses to
this question will be forwarded to the originator. Please see below
for my
response already sent to the originator.

Deb Kramer

>---------------------------------------------
>we print plastic cards on
>a screen press using uv
>or ovens to dry the ink.
>Does anyone know what
>percentage of ink is
>retained by the plastic. I am trying to calculate
>fugitive emissions. Thanks.
>
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To my knowledge none. Because plastic is not permeable (like
paper is) all
the
solvent typically would be driven off in the drying process. Keep in
mind,
your UV curable inks will have negligible emissions to begin with; its
the
convection cured inks that will be the targets. Also, if your state
allows
you
may be able to claim a retention factor for the solvent in your shop
towels.
Each state is different, but for instance in Illinois you can take a 50%
solvent retention factor IF, and only if you are also complying with
the shop
towel handling and storage rules as well.

I will run this past Marci Kinter at the Screenprinting & Graphic
Imaging
Association to see if she has any additional insights. Gary Jones @
GATF also
received this original message and may have additional comments.

Additional Info: The U.S. EPA has not made a final determination
on retention
factors using permeable substrates (paper, etc). This determination
currently
is focusing on offset lithographic printing.

As far as current solvent retention allowances - each state is
different. If
you reply to this message with the state that you are located in we
can obtain
more detailed information for you.

Thank you for accessing the PNEAC web site.

Best Regards,

Deb Kramer

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Debra Kramer
NOTE: New E-mail Address dkramer@wmrc.hazard.uiuc.edu
IL Waste Management & Research Center / IL Dept of Natural
Resources
(PNEAC/GPP http://www.pneac.org)
1010 Jorie Boulevard, Suite 12
Oakbrook, IL 60523
630/472-5019
630/472-5023 Fax
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