From: Richard Sullivan (richsul@cybermesa.com)
Date: 09/01/01-06:25:03 PM Z
Reagent grade is often only the technical grade that has been tested and
certified. In the past there was a big difference but today in many, if not
most cases, the only difference is in the certification. Modern automated
manufacturing techniques make for better efficiency to make one batch on
one line than to try to make one real good batch and one not so real good
batch.
This is not always true so you have to be careful but if the stuff looks
clean, it is probably on for most printing processes. For film, go for
quality stuff. I used to use Arm and Hammer Washing soda for print
developers, It was sort of brownish in the tray but worked fine.
An interesting bit: Reagent grade must be packed at the source. If a
company buys 100 lbs of reagent grade sodium sulfite and repacks it into 1
lb jars it is no longer reagent and cannot be sold as such unless re-tested
and re-certified. However it is common practice, widely done, to do just this.
As I understand it the testing is done in-house and no one ever really
looks at the results unless there is an audit or an issue arises. It is
more or less based on the honor system until the lawyers get involved.
--Dick Sullivan
At 12:09 PM 9/1/2001 -0400, you wrote:
>"Jeffrey D. Mathias" wrote:
> >
> > I believe the "ultra pure" or "pure" grade would be the purest and most
> > expensive. This would likely be overkill for a photographic process.
>
>At Baddley and another (I forget which) company the "pure" grade was the
>least expensive, reagent the most expensive, sometimes considerably
>more. I'm sticking to reagent for all metals, but some of the lesser
>chemicals (by ratio) in the formulas I'll get technical or pure. For
>instance, sulfuric acid or potassium iodide can be had for a third less
>the cost in technical or lab grade. These are often listed as "for
>demonstration or experiment purposes." What could be more experimental?
>
> > I would recommend the "reagent grade" as this will likely pay for itself
> > in consistency of results. There are two types of reagent grade
> > available. One has an analysis and the other does not.
>
>Is this what "ACS" stands for after the word reagent?
>
>thanks
>
>--
>Darryl Baird
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