Printech Archive, April, 1999: Re: EPA Method 24A

Re: EPA Method 24A
Tue, 27 Apr 1999 09:59:34 EDT

Dear Betsy:

First and foremost Method 24A should not be used to determine the VOC content
of any printing ink, except for publication rotogravure inks and related
coatings. EPA has issued guidance on this and we are in the process of
working with EPA to further clarify the applicability of Method 24A.

Both Method 24 and 24A are VOC content (not VOC emission) tests. There are
several steps included in each method, including a weight loss, water
content, and exempt compound determinations. This weight loss determination
plays an important role in each of the tests. The most significant difference
between the two methods is that the weight loss portion of Method 24 is
conducted at 110 degrees C for one hour, while Method 24A is conducted at 120
degrees C for 24 hours. Obviously, the weight loss for lithographic and
screen inks measured with Method 24A would be greater than that measured from
Method 24.

In terms of testing each batch of ink, this is unusual and generally not
required for printers. Given the number of batches of ink that a typically
printer would use, it would be virtually impossible, let alone extremely
expensive to conduct. A batch of ink could be as small as one pound or as
large as 500 gallons. It would be better to have the ink manufacture provide
VOC content information based on formulation data and Method 24 testing
results on the input materials that go into the ink. The ink manufacturer
could periodically sample prepared inks and compare the results to the
predicted VOC content based on formulation.

The other issue is that in order to for the DEP to impose such a requirement,
there needs to be a limit on the VOC content for each ink and type of ink. If
the draft permit does not contain a VOC content for each ink and type of ink,
then this type of testing is not justifiable. If the permit does contain VOC
content limits, then they should be revisited. Neither EPA or the DEP have
any VOC content limits for either lithographic or screen printing inks. What
this means is that unless, there is a specific reason to take a limit on the
VOC content of inks, then one is not necessary. If VOC content limits were in
any previous permits, then they will have to be modified prior to the
issuance of the Title V permit.

Gary Jones



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