Verdigris from acid and copper?

[Susan Kline]

Dear Jim,

Y'all have written some good points. Here are a couple:
>Let us not confuse 'Sulfate' as seen on all brass/copper/silver, etc. with
>verdigris.

I'm not chemist enough to know the difference, or how the greasy waxy
aspects mesh. My dictionary claims that verdigris is made up of one or more
copper acetates, from the action of acetic acid on copper.

So, chemists, (Tim Keenan: help!), does acid always play a role in verdigris
formation? Is there a practical way to neutralize the acid in pianos already
having the problem, and has anyone tried it? One might ask people who work
on preservation how they neutralize acid in old books, drawings, etc. (Anne?
Do you have any friends doing stuff like this?)

I've heard for years that the paraffin made the difference. Could it be that
the _waxy_ as oppposed to the "greeny" aspect of verdigris is what causes
the normal acetate to cause a mechanical problem? Perhaps the waxy crud of
the paraffin residue traps the acetate, and without the paraffin it sloughs
off, causing no trouble? Does anyone here know? Is verdigris ever "waxy" if
wax or grease weren't present to begin with? Degreasing as a cure is
probably a blind alley -- harder to do than replacing parts (if possible at
all) -- but I wonder if acid reduction might be feasible.

>The better manufacturers tried to
>solve the moisture related problems with their instrument and the less better
>(hows that for grammar Ms. Susan?) manufacturers didn't. 

Don't know about the grammar, but it's great for tact!

>p.s. The reason for the exclamation point and the question mark together is
>that my yankee daughter is standing here telling me how to punctuate the
>approbation ya heah.  Damn yankees.

We can't help it! Spelling and punctuation are in our genes, and qualify as
a force of nature, like verdigris ... and they're just about as popular! 

Approbation -- that's what we spellers have to do without! 

Have a _great_ day, in spite of creeping green crud, nemesis of
conscientious piano builders.

Ms. Susan


----------------------------------------------------------
>
>In a message dated 2/12/98 2:40:59 AM, skline@proaxis.com wrote:
>
><<"If rebushing, for instance, could one wash the cloth thoroughly to remove
>any sulfuric acid mordant, and then rinse in a baking soda solution? Has
>anyone ever tried this?">>
>
>James, Susan, et al;
> If there were enough sulfuric acid in the atmosphere, or in bushing felt, to
>cause this problem on any instrument, tight action centers would be the least
>of our problems :-)
> Copper is way too soft to use as action centers. Copper mixed with zinc(in
>various ratios and including other trace elements) gives us Brass.  Brass is
>what center pins are made with and they are sometimes plated with nickle or
>other substances for sulfate formation resistance.
>  Sulfate formation is caused by many factors and I am sure that sulfur in
>some form plays a role in some cases.  Let us not confuse 'Sulfate' as seen on
>all brass/copper/silver, etc. with verdigris.  Sulfate forms 'on/in' the
>surface of the metal and will leave pits in the surface as a result of the
>chemical processes involved.  Verdigris forms 'at' the surface of the metals
>and does not leave pits in the metal. (or at least not to the extent that
>Sulfate does) Another way of saying this is that Sulfate "grows into" the
>metal and Verdigris "grows away" from the metal.
>  Copper Sulfate forms on all Copper containing metals including center pins.
>Copper Sulfate can be kept in check by polishing the surface of the Copper.
>Playing a piano causes the center pins to be "polished" by the action of the
>felt thus constantly removing the Sulfate forming on the center pin. 
>  An action with sluggish keys, due to non use, allowing sulfate to form
>unchecked, can be successfully treated in any number of ways.  Some methods of
>freeing action centers that are sluggish due to non use are water/alcohol
>treatment, lubricants of various types, and repinning.  If the nonuse
>formation of sulfate was the problem and the piano is going to be used/played
>after this treatment the sluggishness will not reappear.
>  OTOH If our good friend Verdigris is the culprit we can wash, flush, repin,
>rebush all we care to and the problem 'will' resurface and it is not a matter
>of "if" it is a matter of "when".  The reappearance of the problem 'will'
>happen without regard to whether the piano is played once a month for ten
>minutes or every day for three hours.
>  In my experience with this beloved substance the better the manufacturer the
>more often this problem will be evidenced.  The better manufacturers tried to
>solve the moisture related problems with their instrument and the less better
>(hows that for grammar Ms. Susan?) manufacturers didn't.  As a consequence we
>see the problem of Verdigris on the S7Ss, M&Hs etc of the world much, much
>more often than on the Wurlitzers, et al.
>  Verdigris can be compared to the ubiquitous "dampp chaser under plastic
>elbow syndrome" in that the attempt at solving one problem lead to the
>creation of another problem that would not show up for years.
>  My suggestion for solving Verdigris problems is to replace all parts thus
>affected.  My suggestion for continued repair/rebuilding work for ourselves
>and future generations is to carry verdigris along with us and infect all non
>infected piano.
>  Y'all have a good day , ya heah?!
> Jim Bryant (FL)
>
>p.s. The reason for the exclamation point and the question mark together is
>that my yankee daughter is standing here telling me how to punctuate the
>approbation ya heah.  Damn yankees.

---------------------------------------------------------------------

Susan Kline
P.O. Box 1651
Philomath, OR 97370
skline@proaxis.com

"Enormous amounts of information are availble, including, however, very
little reliable data on what it all means."
			-- Ashleigh Brilliant