How to check a cornet leadpipe for rot?

[Robert P]

What's the typical way to inspect the leadpipe on a cornet for red rot? You can't just pull out the tuning slide and look down it. There are endoscopes on eBay but the fixture for the light looks like it wouldn't go around the curve in the tubing. Looking at inspection scopes at Harbor Freight I don't think they'd fit.

Thoughts?
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Getzen Eterna Severinsen
King Silver Flair
Besson 1000
Bundy
Chinese C

Getzen Eterna Bb/A piccolo
Chinese Rotary Bb/A piccolo

Chinese Flugel

[Bob Stevenson]

Well you have answered your own question really!......as you surmise there IS no real way to inspect the inside of a cornet leadpipe apart from a suitably thin endoscope, or possibly one of the thin rigid instruments for exmining rifle lead into the rifling via the breech...a VERY expensive device as I recall.

Then again, do you really need to do this, or even be concerned about it?.....during my 50+ years in brass bands I only know of one case of "rot" in a leadpipe and this is in a tenor horn (here in my house) where the leadpipe is very thin and now has actual holes. However, this instrument was made in 1909 by Hawkes, is completely covered in engravings so replacement difficult and anyway plays beautifully with tape over the leadpipe below the mpc ferrule, so, in a plus hundred year instrument not worth being worried about in the great scheme of things..........

In the extremely unlikely event that you bought a 50 or 60 year old instrument and discovered "rot" in the leadpipe either tape over it and get on with making music or get the pipe replaced

Actually, the horn above does not have "rot"...ie corrosion it's plagued by another age problem never mentioned here, namely metal fatigue due to changes in the brass resulting in increasing brittleness.....

[Robert P]

[Bob Stevenson]

As we know brass is a fairly simple alloy of copper and zinc. However, it's not so widely known that brasses can vary widely and also contain other constituents to aid the particular use that the brass is going to be used for, such as the inclusion of lead in the 'engraving brasses'. Brass instrument factories don't always purchase specific brass alloys but are prone to using 'deals' just like many other industries.

Two areas specifically come to mind in cornet making........the heat treatment of the metal at various stages of manufacture is vital as the tonal quality will change according to the degree of anneal and this is likely to be much more important in a good cornet than in a trumpet. Also many of the 'better' cornets are largely made of nickel, at least for UK made instruments.

[Robert P]

[James Becker]

One need not have a look inside, the indicators are easily seen from the outside. Lacquered brass will have pink dots with a dark red "bulls eye" in the center. Silver plate will have blisters where moisture has leached from the inside out. Flake off the blisters and you will find the pink spots with a dark red "bulls eye" just as you see on brass.

Many makers have increase the copper and reduced the zinc in alloys to prevent red rot (dezincification).

If you want to see corrosion deposits just shine a LED penlight down the mouthpiece receiver

My 2 cents.
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James Becker
Brass Repair Specialist Since 1977
Osmun Music Inc.
77 Powdermill Road Rt.62
Acton, MA 01720
www.osmun.com

Our workshop is as close as your nearest UPS store https://www.ups.com/dropoff?loc=en_US

[Robert P]