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Discussion in 'Trumpet Discussion' started by anthony, Feb 6, 2016.
Ok, when I said polished out I should have said polished. After polishing it it looks ok
According to Perry's Chemical Engineer's Handbook, brass dezincification comes in two forms:
A 'general' form which looks like patches of pink lichen, frequently where moisture has managed to diffuse between metal and lacquer. Superficial, slow growing, no cause for serious concern.
A 'pitting' form that develops as craters on the wetted surface, eventually breaking through to be seen as small pink circles with dark centres indicating perforation of the tube wall. This is the bad one.
The precise mechanism is still a bit conjectural, however the following is known:
It doesn't affect low brasses with less than 15% zinc.
Intermediate/high brasses above 15% zinc can be 'immunised' by including small quantities of arsenic, antimony, or phosphorus.
The process is galvanic and therefore cannot proceed in the absence of moisture. Storing the instrument dry is good.
Substantial protection can be provided by a 'passivated' surface: ie one where the surface is protected by a strongly bonded molecular film. This may be promoted by frequent application of valve oil IFF it contains a recognised copper passivator in its formulation.
Vigourous mechanical 'cleaning' inside tubing tends to remove any passive protection and expose bare metal to attack. Best to apply judiciously and take steps to restore passive surface afterwards.
Strong evidence that the pitting form of attack is sped up in presence of sulphides. Oral hygiene is a significant factor.
Hey, this is great. Best info on it that I have found. Makes sense that water is getting in between lacquer and brass. Thanks for sharing.
I have a bit of a learning problem so try to understand what you are saying Seth of Lagos using Valve oil IFF is good but where do I find this?
Also I noticed this on the Lee Valley Tools website would that help at all? This website has many things is there any lubricant at this store worth buying? I am going there tomorrow. It is out of town for me but I have to be in Ottawa so will go there if it is worth for me to buy anything there. Thanks
AutosolÂ® Metal Polish - Lee Valley Tools
Sorry. Mathematics jargon.
IFF is shorthand for 'if and only if'.
ie. a valve oil really needs a copper passivator in it to give any serious degree of protection against this sort of corrosion. Maybe a number do, but the only brand I've come across that claims to include one is Monster Oil. Never had the chance to try their product, so I can't say any more than that.
The only trumpet related lubricants I would buy from a general hardware store are petroleum jelly and sewing machine or hair clipper oil.
Thanks for the information. Lee Valley Tool is More a woodwork supply store for people who are in general buying for small stuff or big stuff relating to building anything with wood like cabinets they want to build.a specialty store.
Petroleum gelly I have lots of that but will check where I can get Monster oil.
I really just looking to buy something to clean my Trumpet with to help slow down the erosion cause by red rot
Most any polish will shine it up and make it look better but the damage is done. Good maintinace and lubrication practices will be most beneficial. Stay away from polishes with abrasives like Brasso although they will work there's no reason to remove more metal than you have to
Have a think about using something like this for external protection : https://en.wikipedia.org/wiki/Renaissance_Wax
I wasn't able to find it in the UK last time, but I now use something similar for my raw brass and 'part lacquered' instruments (as opposed to trying to keep them bright and shiny).