 The Clarinet BBoard
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Author: knotty
Date: 2009-11-08 17:41
I have four refurb clarinets now, gotten from the auction site and all four has this coating on the keys, some rubs off very easily to bright nickel while others you have to polish it on the cloth wheel with polishing compound.
Some of the stubborn coatings seems to be a slightly sticky substance as opposed to just a silverware tarnishing.
I'm just curious what causes this hazy coating, is it from just sitting in the case for decades?
Thanks, knotty
~ Musical Progress: None ~
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Author: tictactux ★2017
Date: 2009-11-08 18:02
I'm constantly wondering about that too.
Maybe some nNickels are more prone to "deep tarnishing" than others. Maybe it's fumes evaporating from the case lining, maybe it's sweat and other physical abrasions, maybe it's leftovers from unsuccessful prior attempts at polishing, maybe it's the thickness of the plating, maybe it's what's beneath the plating - I don't know.
--
Ben
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Author: Chris P
Date: 2009-11-08 22:39
And I'm someone else who's wondering about these two different types of oxide formation on nickel plating too - the bloom or dusty type one (like the light condensation you get from breathing on cold metal) that rubs off with your fingers to leave shiny nickel beneath, and the stubborn one that can only be machine polished to remove it.
What, why, and how?
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: Don Berger
Date: 2009-11-08 23:19
Prob. these metal tarnishes are oxides, sulfides, multi element [oxy sulf] due to slight reactivity with atmospheric gases. Ni and Cr are less active than Fe and our fav. Ag blackens easily. Chem 101. "nuff fer naow ? Don
Thanx, Mark, Don
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Author: BartHx
Date: 2009-11-09 00:20
Digging back into my memory banks, I seem to recall that some of the materials that used to be used in making cases outgased sulfur compounds. This would go along with what Don indicated. Silver sulfide will form fairly quickly and is black (think of a sterling utensil that has been exposed to egg yolk and not promptly cleaned). Silver oxide will form more slowly, but will eventually look fairly similar. As I recall, the sulfides of nickel and chromium create the colored tarnish that is so hard to remove. My guess is that the ease of removal relates to the number of bonds created in the formation of the compounds and the geometry of the molecules as they relate to the metalic bonding within the metals from which they are formed.
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Author: Gordon (NZ)
Date: 2009-11-09 01:36
What I do know from experience is that the fumes from polyurethane varnish can tarnish fresh nickel plating to a dull, rough off-white overnight, and it needs buffing to remove it.
And several manufacturers have had problems with vapours from case materials doing much the same, but more slowly.
Nickel seems to have some strange reactions.
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Author: mrn
Date: 2009-11-09 03:33
I am hardly an expert on this subject, but I was able to do a little bit of informal research and dug up a few partial answers. What I found confirms what Don said--oxides and sulfur-compounds--but it also raised a few new questions.
Nickel, when it oxidizes, forms a protective layer (believed to be at least partly made up of NiO) that resists further corrosion (at least by oxygen, anyway). One book I located with Google suggests that this is responsible for the way nickel fogs up over time (click the link below, read about the "passive film" formed on nickel, and scroll up to p. 3 where it says that fogged nickel is an example of this kind of protective layer). As the book mentions, this NiO layer is really hard to remove (as you would expect of a protective layer).
http://tinyurl.com/y8eufgw
Now, another book I located described the fogging of nickel "in industrial atmospheres" [whatever that means--I think it means in the presence of nasty chemicals like sulfuric acid, but I'll defer to the chemists/ChemE's on this] due to the formation of nickel sulfate (NiSO4). It described NiSO4 as a non-protective film. Now, what I recall from having done some reading in material science is that there are basically two reasons why a layer of corrosion would be considered non-protective--one is that the corrosion layer doesn't sufficiently cover the underlying metal (because it's too porous), the other is that the corrosion has a tendency to crack and flake off (the way silver tarnish does--which is why it rubs off so easily).
I don't know which of these two reasons applies to NiSO4, but if it's the latter, perhaps that would explain why some kinds of nickel tarnish come off easily and others don't. Maybe somebody on the BBoard with more chemistry/metallurgy background (who can better understand these references I found than I can) can tell us.
http://tinyurl.com/ydfghpt
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Author: Gordon (NZ)
Date: 2009-11-09 10:21
"the other is that the corrosion has a tendency to crack and flake off "
I would have thought that refers to the behaviour of rust (and anything similar), which is rather different from the behaviour of silver tarnish. No?
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Author: Don Berger
Date: 2009-11-09 14:08
I agree with most of the above , whether from chemical experience or hypothesis. Being [someshat] interested in NiSO4 chenistry, I made a quickie search and found that Wikipedia et al will give you more info than what you may want. It and copper and zinc sulfates are possible IMHO from our widely-used [poorly named] Nickel Silver alloy [giving blue and green tarnishes. If the atmos. contains SO2, water and perhaps a trace of Ozone to oxidiize the SO2 to SO3, its water solution is sufuric acid. "Johnny was a chemist's son, but that he is no more, what he thot was H2O, was H2SO4 " !!. Yup, its BAD!, Don
Thanx, Mark, Don
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Author: mrn
Date: 2009-11-09 14:24
Gordon (NZ) wrote:
> I would have thought that refers to the behaviour of rust (and
> anything similar), which is rather different from the behaviour
> of silver tarnish. No?
Well, as I understand it (and again I'm no expert), different kinds of corrosion have differing degrees to which they crack and lose their structural integrity. Rust (iron (iii) oxide) is very susceptible to cracking and flaking. Silver tarnish is less so, but it still doesn't hold together like fogged nickel does.
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Author: knotty
Date: 2009-11-09 16:01
Thanks for the research and info guys. Yes the coatings on these refurb clarinets are very even like it was put into a fuming or smoke chamber, so I guess it must be a vapor or something that comes from the case materials.
To do a good job in removing the coating, I have to take all the keys off, so, while the keys are off, might as well re-pad it and clean the body too the thinking goes.
I tried different solvents on a Q-Tip to see if it would melt the coating but nothing so far works. (it sure would be nice if some solvent took all the coating off, maybe there is one?) Silver polish works a little but requires a lot of rubbing in which case the buffing wheel with jewelers rouge is a lot easier.
knotty
~ Musical Progress: None ~
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Author: Chris P
Date: 2009-11-09 16:18
Years ago I stuck some masking tape on an old German (Adler) nickel plated soprano sax to hold the lead for a leaklight in place when it was up the bore, and the nickel plating had gone dull grey - the kind of tarnish that can only be removed by machine polishing.
When I took the tape off the area beneath the tape was left shiny and bright compared to the rest of the instrument, so something in the glue used on the masking tape did wonders to remove this kind of tarnish.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: BobD
Date: 2009-11-09 17:55
"Rust (iron (iii) oxide) is very susceptible to cracking and flaking."
Iron oxide doesn't always flake. The copper bearing iron alloy developed by USS as used on the Chicago Picasso statue develops a thin relatively protective layer that resists flaking. The "fog" type of film that one sometimes sees on nickel plating is sometimes just normal atmospheric gunk that is easily removed with lemon oil or wd40 or kerosene....or even Windex. I've not encountered "hard to remove" discoloration on nickel plating. Sometimes unplated nickel silver is confused with nickel plating.
Bob Draznik
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Author: mrn
Date: 2009-11-09 18:43
BobD wrote:
> "Rust (iron (iii) oxide) is very susceptible to cracking and
> flaking."
>
> Iron oxide doesn't always flake. The copper bearing iron alloy
> developed by USS as used on the Chicago Picasso statue develops
> a thin relatively protective layer that resists flaking.
True. I have a question for you, though. Is that a different iron oxide?
The reason I ask is that my materials science book lists "Iron" as a "protective" metal having a Pillings-Bedworth ratio of 1.77, but Wikipedia lists 3 different oxides of iron with different P-B ratios, giving a ratio of 2.14 for iron (iii) oxide [which is what we normally call rust, I think] and 1.7 for iron (ii) oxide. The higher P-B ratio oxides/metals are the ones that flake, or so I've read.
So--to me (and I'm EE/computer guy--so I'm learning about this as I go)--it sounds like there's a protective iron oxide that's iron (ii) oxide and also a non-protective iron (iii) oxide (commonly referred to as rust). Does that sound right?
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Author: BartHx
Date: 2009-11-09 19:03
In cleaning keys with minimized elbow grease and without resorting to the wheel, I have had great success with MAAS Metal Polish. It does not always remove all tarnishes, but it makes things much easier and is usually all I need. If you keep the cloth that has polish in it when you finish, you can quickly clean keys when they first start to tarnish, buff them lightly with another soft (I use microfiber) cloth and have a horn that is always bright and shiny. You can locate a source by googling MAAS metal polish.
Disclaimer: I have no connection to MAAS products other than being a very satisfied user.
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Author: BartHx
Date: 2009-11-09 19:09
By the way, the MAAS polish is basically non-abrasive. I also use it on my wife's antique silverware collection. It will take a black utensil and make it bright and shiny in a matter of a minute or two (Yeah, I know some people say that should not be done, but her collection is for her pleasure only.)
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Author: knotty
Date: 2009-11-09 23:10
Thanks BartHx, I'll go run down some MAAS tomorrow. I have a very high laziness factor so anything to keep from taking the keys off will be great.
Interesting the masking tape ChrisP.
knotty
~ Musical Progress: None ~
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Author: BartHx
Date: 2009-11-10 05:53
I take the keys off to get them clean to start with. However, touching up things like paddles and finger rings as you go can keep your instrument looking great for a long time. I am one of those who can tarnish silver in an evening of playing, but a wipe down when I finish is all I need to do.
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