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Discussion Starter · #1 ·
Here's an album: https://picasaweb.google.com/103001...DueToLacquerWear?authkey=Gv1sRgCPmNvZnV8uyOKQ

this is a one owner original lacquer horn. I'd say that the original lacquer coverage was better than 90%. Always taken care of, pampered horn.

You can see after delacquering, the "highs" and the "lows" where it was respectively lacquered and where the lacquer wore off/flaked

I have seen less material removal on heavy buffed relacquers than on the places that became unprotected on this horn. Let alone, a careful relacquer done to protect not to bring up to showroom quality again.

But IMHO the best option is to delacquer and leave it bare brass. No bare brass horn loses overtime the amount of material a lacquered horn loses (that's if you're not constantly polishing it up to have a shiny horn)
 

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Thanks for that, Juan.

Our conversation regarding pitting corrosion certainly brought up many thoughts. For one, we have the evidence that in the worst case of aqueous environment - the unprotected interior of the horn - we don't witness pitting corrosion. What I had previously failed to consider is the contribution of environment to the galvanic cell(s) on the exterior surface of the horn. We certainly witness enhanced pitting on horns near coastal regions - hence my professed stance of needing to protect the horn against further corrosion by maintaining some finish.

For those unfamiliar with galvanic pitting corrosion, here it is in a nutshell: A galvanic cell is one in which a potential energy drives the removal of metallic ions from the surface of a metal with the electronic balance provided via a conductive aqueous path. The classic case is a ship's hull made of steel sitting in sea water. The corrosion of the hull can be reduced by using a sacrificial anode with a greater differential potential - hence the anode corrodes in preference to the steel hull.

Pitting corrosion occurs when the active area of the galvanic cell is reduced and the local flux of ionic exchange is enhanced - an example is when a storage tank with an internal coating loses pinpoint coverage of the base metal. In the case of a saxophone, this occurs when the lacquer breaks down on the microscopic level and allows tunneling to the base metal. The resultant corrosion cell has enhanced activity and leads to accelerated corrosion in a confined area >> pitting that drills into the body of the horn.

That leaves us pondering the answer to the problem. I see three possibilities that I present in no particular order. The first is a more impermeable and robust finish ala the epoxy finishes that have become popular. The second is the unlacquered finish - WITH THE CAVEAT that it will still be vunerable to corrosion and that local galvanic pitting corrosion may occur, for instance, at crevices such as body/post joints, threaded regions, and spring mounts. The third option is heavy plating - to date we have seen nickel, silver, and gold.

Comments???
 

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So, if I get it right, brass under lacquer was preserved much better than bare brass parts? Right? Therefore lacquered parts are "higher" and bare brass parts were "eaten". So if brass becomes unprotected without lacquer, why then you need to strip the horn to preserve it? Isn't it better to just spot lacquer those bare brass parts to preserve it? I'm kinda lost here :)
 

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Discussion Starter · #4 ·
So, if I get it right, brass under lacquer was preserved much better than bare brass parts? Right? Therefore lacquered parts are "higher" and bare brass parts were "eaten". So if brass becomes unprotected without lacquer, why then you need to strip the horn to preserve it? Isn't it better to just spot lacquer those bare brass parts to preserve it? I'm kinda lost here :)
no you got it partially right.

What happens is that when 2 different electronic potential parts are on the same surface pitting occurs. I you have 100% lacquer there's wear on the lacquer. But if you have an open pore on the protective coating, that part on the substrate gets destructively eaten way faster than bare subtrate exposed to the elements and not buffed.

I've lived most of my life in coastal enviroments (cities by the sea and by big rivers) and the most stable finish is no finish at all.
 

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I've lived most of my life in coastal environments (cities by the sea and by big rivers) and the most stable finish is no finish at all.
What's your experience with pitting on plated horns?
 

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Thanks for your answer. Very interesting. Something new to me, so I have a question in this regard.
My SBA is an original lacquer and in pristine condition, but has a corrosion around low Eb keycup. I was told by a tech not to worry about it, as the corrosion itself is like a "barrier" and it's protecting the brass underneath. I'm posting some zoomed pictures, it looks much less actually in reality. I would appreciate your input on it, should I do anything to it or leave it as is?
Thanks!





no you got it partially right.

What happens is that when 2 different electronic potential parts are on the same surface pitting occurs. I you have 100% lacquer there's wear on the lacquer. But if you have an open pore on the protective coating, that part on the substrate gets destructively eaten way faster than bare subtrate exposed to the elements and not buffed.

I've lived most of my life in coastal enviroments (cities by the sea and by big rivers) and the most stable finish is no finish at all.
 

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Discussion Starter · #7 ·
What's your experience with pitting on plated horns?
they're worse than laquered horns.

Thanks for your answer. Very interesting. Something new to me, so I have a question in this regard.
My SBA is an original lacquer and in pristine condition, but has a corrosion around low Eb keycup. I was told by a tech not to worry about it, as the corrosion itself is like a "barrier" and it's protecting the brass underneath. I'm posting some zoomed pictures, it looks much less actually in reality. I would appreciate your input on it, should I do anything to it or leave it as is?
Thanks!
leave it as is for the time being.

ADD: if that was my horn and I'd intend to keep it for more than 10 years I'd delacquer it, but I don't know how old your pads are
 

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My pads are really good, like new with 95% life in it.... I will have this SBA forever, but to strip such original horn would be very hard for me. Is there anything else I can do about that spot?

they're worse than laquered horns.

leave it as is for the time being.

ADD: if that was my horn and I'd intend to keep it for more than 10 years I'd delacquer it, but I don't know how old your pads are
 

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Thanks for your answer. Very interesting. Something new to me, so I have a question in this regard.
My SBA is an original lacquer and in pristine condition, but has a corrosion around low Eb keycup. I was told by a tech not to worry about it, as the corrosion itself is like a "barrier" and it's protecting the brass underneath.
I won't commit an opinion as to whether to delacquer or not.

Regarding the corrosion acting as a barrier: That is only true in the case of a limited number of oxides, silver being one case, where the oxide is conductive and does not spall. I cite silver here because, in my former life as a shipboard electrician, I worked on high current breakers with silver contacts. The procedure for refurbishing silver contacts is to leave them alone rather than try to remove the oxide. Of course, on a plated instrument, once the plating is penetrated, you are back to the issue of exposed metals of dissimilar potentials with a shared conductive path in an aqueous environment (bonus points to the reader recognizing the definition of a galvanic cell).

Brass and copper have several oxide states - most of them either porous or, worse, compressive in nature such that they tend to spall off in chunks leaving fresh material exposed e.g. the classic red rot.

I believe that Juan tends to go a step further with his own horns and uses a protective wax applied periodically to slow any general corrosion due to sea shore environments.
 

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My pads are really good, like new with 95% life in it.... I will have this SBA forever, but to strip such original horn would be very hard for me. Is there anything else I can do about that spot?
Juan - What of using wax over that area to slow the process?
 

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Z - Do you use any wax or polish?
 

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Funny you mention that, I use the same polish on my cars and lacquered saxes (and guitars, for that matter):

Meguiars Cleaner/Polish. Highly recommended for cleaning and protecting lacquer finishes - in the boutique guitar community, many builders use this line of products on expensive guitars.
 

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It's a curious thing to see such deep corrosion. Where I've seen it the player has been acidic i.e their sweat is more corrosive thatn usual and you can see where their hands have been in contact.
Where I've encountered galvanic corrosion before was Stephen Howard talking about Martin toneholes potentially falling off. The description there was of two different metals connected with mildly acidic solution - a mild current flows for galvanic corrosion to occur.
In the example of the lacquered saxophone I'm not sure you are going to have the conditions in the places shown for galvanic corrosion to occur.
The way to solve galvanic corrosion is to prevent a current and/ or to shield the the metal by coating with plastic of epoxy. As most modern lacquers are epoxy-based it would seem to be ideal for preventing galvanic corrosion.

So, in my opinion (and I'm no expert), either this isn't galvanic corrosion or the advice to delacquer would seem to be wrong.
 

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Discussion Starter · #18 ·
Juan - What of using wax over that area to slow the process?
That's what should be done even on plated horns. A goot coat of carnauba wax and periodically maintainence of that coat, it's promoting a nicer, even and more stable oxide barrier ("patina")

My pads are really good, like new with 95% life in it.... I will have this SBA forever, but to strip such original horn would be very hard for me. Is there anything else I can do about that spot?
Most likely what's causing that spot is the removabell. My bet's it's not that well glued, and the metal is touching like on an intermitent shortcircuit. That's why the pitting is only there. That and the saliva acting as a permanent humid and salty and acid media right there. I'd solder the bell, remove the pitting... t's going to be a nasty view, how a horn so otherwise nice has that amount of pitting... most likely it's going to need sanding (even filing maybe) to get a good surface then buff then either wax it or touch up the lacquer there after you soldered the bell on.

Did you guys hear about the SBA tenor I'm selling? :)
This was bound to happen hahahahahahahaah
 

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I reference the interested reader to "Principles and Prevention of Corrosion" by Denny Jones.

Foremost, let's recognize that there exist many forms of corrosion. I agree, Oric, that this is not the case of dissimilar metals such as in Stephan Howard's example. Differential electric potentials may also be established just by a gradient in chemical concentration. Regardless, once a cell is established, one needs to identify its characteristics and determine how to either interrupt the reaction or diffuse it.

Although I have a knee-jerk response to even seeing most threads about delacquering, I have to consider Juan's hypothesis as having some credence - especially in the light of having played so many vintage horns over the years with pitted lacquer yet pristine bores. Now, whether those bores remain so smooth is a testament to the fact that there are no posts, plates, joints or otherwise, I just don't know.

(FWIW and OBTW, I use a Shove-it swab and periodically treat it with lemon Pledge so the bore of my horns is smoooooth and lovely. No funk, no stink.)
 

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Discussion Starter · #20 ·
that was going to be my second comment, even the ugliest pitted rotten horn has a smooth bore. The plating inside is also perfect most of the time even when it has flaked and pitting lifts blisters between the substrate and the plating.

the only way to deal with this is either refinishing periodically or just call it a lost battle and use no finish at all (just waxing of the outside of the horn to prevent spots of verdigris due to the occasional saliva drop)
 
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