Here's our conversation & some followup. Hope it helps.
Edrena

-------- Original Message --------
Subject: Fw: Query on pH test strips
Date: Mon, 11 Sep 2006 13:10:39 -0400
From: Technical Support NJ >
To:

Please see below for answers to your questions. I hope you find them
useful.
Should you have any further queries, please feel free to contact me
either via e-mail or on 1-800-942-8626 xt 8323.
Regards, May Taraneh Burwell-Teran
Senior Technical Support Representative

I preserve various things - pickles, juice, jam, etc. I belong to a
very civilized newsgroup (rec.food.preserving) that has some questions
on how to know how acid an untested recipe is. Food rated at pH <= 4.6
can be preserved by boiling water bath canning, anything above that
needs pressure canning. We like to experiment, but not with our
health.
I use the CF test strips 2613991 ... They have served very well for
me - but I have a few questions:
1. Are the test reagents food safe? Your site says: "All the dyes are
chemically bonded to the paper and cannot be leached into solution;
problems associated with contamination of the sample and resultant
anomalous readings are avoided."
"Although chemicals cannot be leached into the solution we do not
recommend use of this item directly with the finished product (i.e.
it is better to remove a small sample of the item and test that
instead of dipping the paper into the whole jar of finished product)."

2. Is there a problem with testing at various temperatures from cold
to over boiling?
"The paper itself will hold up with cold or hot samples. However,
if
temperature affects the pH of the item, you will have results of the
product's pH at time of testing."

3. My container shows the pH ranges in whole numbers only - which
colors are what fractions? Your site says: "The resulting combination
of colour differences gives an extremely clear and accurate visual pH
value."
This strip reads the pH in whole unit increments and not fractions.
We do, however have other products which read pH in 0.2 or 0.5
graduation units from pH 3.8 - 5.5 and the charts for these are on
the packaging of the product itself. [This is item #2627-990]

4. Do you have a food rated product, both for brewers and canners in
the ranges we look for?
"Unfortunately, none of our pH indicator strips are certified for
direct use with food (i.e. with the finished, packaged product as
opposed to a small sample of the finished product)."
[I asked them to consider us when developing new products.E]

5. Some of our correspondents are world-wide. Is your product
available in most countries? Some of our correspondents are from
Canada, Central America, Hong Kong, Thailand, England/Scotland/
Ireland, Germany, and Israel.
"Following is the link with our complete list of worldwide
distributors which include the aforementioned countries.
http://www.whatman.com/support/?pageID=3.8"