Re: [ARSCLIST] Cleaning fluid, brushes, etc.

[Eric Jacobs <ericj@xxxxxxxxxxxxxxxxxxx>]

Regarding the cleaning of acetates, with some understanding of the
problem, the choice in cleaning solutions/methods becomes clearer.
At least in my mind.

One way to think of palmitic acid, is that is it a kind of "margarine".
Palmitic acid (and stearic acid, the other part of that white greasy
film that you find on acetates) is basically hydrogenated castor oil,
castor oil being the plasticizer in "acetate" (cellulose nitrate).
Margarine is basically hydrogenated vegetable oil.  Both palmitic
acid and margarine share carboxylic acid (for example, palmitic acid
and stearic acid) in common.

You can read more about this in the ARSC journal article
"Selected Acetate Disc Cleaning Methods" (1997, Paton et al).  The
margarine analogy is mine, but the hydrolyzing of the castor oil
by breaking one or more ester bonds, releasing various carboxylic
acids comes straight from the ARSC journal article.

So if you are cleaning margarine (or any fatty acid), what might
you use?  If you look at a restaurant, they reach for the clear
ammonia - not mineral oil.  I recommend the same - good old
NH4OH (aka ammonium hydroxide, or clear ammonia) - one of the
active ingredients in Windex and other glass cleaners.  The great
thing about clear ammonia is that it is (1) dirt cheap and (2)
has no secret ingredients/additives like most window cleaners.

I mix 1-2% clear ammonia solution with my record cleaning
solution.  For example 50 parts Disc Doctor, 50 parts distilled
deionized water, 1-2 parts clear ammonia.  This works like a
champ and leaves you with a squeaky clean record afterwards.

The use of clear ammonia finds some indirect support in the same
1997 ARSC Journal Article, except that they found that Kodak Lens
Cleaner worked best for cleaning palmitic acid.  But if you
take a close look at the active ingredient in Kodak Lens Cleaner
you find none other than (NH4)2CO3 (ammonium carbonate) - a close
cousin to NH4OH.

As for mineral spirits?  They leave a residue.  So you end up
cleaning twice - once with mineral spirits to remove the palmitic
acid, and then a second time to remove the residue from the
mineral spirits.  How efficient is that?

Although I prefer to use clear ammonia, to be fair I can also
make an untested case for mineral spirits.  If the mineral spirits
do in fact leave a residue, this residue could create a vapor
barrier on the surface of the acetate, and thus inhibit
hydrolyzation and in turn the formation of palmitic acid.  But
this is just theory folks - I haven't personally tested this
myself.  How does any mineral spirit residue affect playback
quality?  I have no idea, but there was probably no residue
present when the acetate was originally cut and played.

I have yet to hear a good explanation of the underlying chemistry
of how mineral spirits work to remove palmitic acid.

On the other hand, the process with palmitic acid is pretty
clear.  The palmitic acid is an "acid" (hence the clever name),
and ammonia hydroxid is a "base" which neutralizes and breaks
down the acid.  Pretty straight forward.

One other process related step - I use a 150x microscope to
check to make sure I didn't leave any palmitic acid deposits
behind in the bottom corners of the groove area.  You can learn
to recognize palmitic acid residue in the groove bottoms with
the naked eye once you familiarize yourself with what it looks
like through a microscope.  But the microscope is best for
positive verification.  In some cases, a worn groove can be
mistaken for PA residue with the naked eye - and you end up
cleaning unnecesarily.

I apologize for the long-winded explanation.  I hope someone
finds this useful.

Eric Jacobs

The Audio Archive
tel: 408.221.2128
fax: 408.549.9867
mailto:EricJ@xxxxxxxxxxxxxxxxxxx



-----Original Message-----
On Friday, November 18, 2005 7:00 PM Martin Fisher writes:
>
> A statement and query about cleaning laquers.
>
> I've been using mineral spirits (essentially paint thinner I'm told) to
> clean laquers (acetates) of the white gunk.  So far I've obtained quite
> excellent results with no apparent damage to the surfaces.  Recently I
> learned that other friends in the biz were using mineral oil (the kind
that
> can be "safely" drank as a laxitive) for the same purpose.  They really
> raised their eyebrows at the use of mineral spirits expressing concern for
> the long term longevity of the media after such a treatment.  Have I
gotten
> the term spirits and oil mixed up here?  I hope not.  Mineral oil has
about
> the same consistency of motor oil and takes about as much time to remove.
> Thoughts?
>
> Thanks.  :-)
>
> Martin Fisher