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radman63 Regular Member
Joined: 30 Jan 2023 Posts: 21
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Posted: Wed Feb 01, 2023 7:35 am Post subject: Red Rot Identification |
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OK. So, I'm trying to learn more about red rot. It seems red rot is "usually" smaller spots of discolored metal that are reddish-pink in color. In many eBay ads, I see large, even patches that are reddish-pink in color, and not the small red dots I've seen on other trumpets.
Look at this listing for example. See the large patches of reddish discoloration? Red rot, or just oxidized brass that can be buffed/polished out? What do you think?
https://www.ebay.com/itm/115681033627 |
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huntman10 Heavyweight Member
Joined: 30 Aug 2017 Posts: 688 Location: Texas South Plains
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Posted: Wed Feb 01, 2023 8:47 am Post subject: |
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That is tarnished brass. The pinkish hue of red rot that might damage a horn is usually under lacquer. Red rot coming from inside shows up as black on silver-plated finish.
Just my speculation of course, but I think the tarnish is chemically similar to the chemical process of red rot, but not focused where it will penetrate and only a few atoms deep. Just polish off the surface of this horn to get shiny brass. _________________ huntman10
Collector/Player of Fine (and not so fine) Brass Instruments including
Various Strads, Yammies, Al Hirt Courtois, Schilkes,
Selmer 25, Getzen Eternas, Kanstuls (920 Pic, CG)
Martin Custom Large Bore, Lots Olds!, Conns, etc. |
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Ronnman Veteran Member
Joined: 09 Aug 2019 Posts: 409 Location: SE Louisiana
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Posted: Wed Feb 01, 2023 9:16 am Post subject: |
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I agree with huntman10. It appears to be brass tarnished over wide areas. Red rot generally shows up as spots and as it advances, dark spots appear in the central part of the spots. See link for a a mix of newer spots and some which are fairly advanced case with the darker centers.
Ron
https://i.pinimg.com/originals/7b/69/67/7b6967e08e97fba9f815fa07139d77f2.jpg _________________ Martin Committee #2 1954
Leblanc “Al Hirt” Model 1966
Olds Custom Crafted Ultra Sonic 1974
Edwards Gen II 2014 |
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SilverSpunk Regular Member
Joined: 17 Oct 2022 Posts: 91
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Posted: Wed Feb 01, 2023 9:41 am Post subject: |
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Yup, this is just tarnish on the surface of the brass, you can see the same reddish discoloration on the bell as well (red rot wouldn't form from the bell in 99 percent of cases).
Red rot is usually pinkish or reddish pinkish spots and it only really gets bad once you see a blueish hue inside the spots. |
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radman63 Regular Member
Joined: 30 Jan 2023 Posts: 21
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Posted: Wed Feb 01, 2023 10:50 am Post subject: |
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Thanks for the replies. I thought these large areas were not red rot, but I wanted some advice. Maybe I'll buy a trumpet like this and see how well it cleans up. |
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radman63 Regular Member
Joined: 30 Jan 2023 Posts: 21
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Posted: Fri Feb 10, 2023 4:45 am Post subject: I bought it |
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I ended up buying the trumpet I referenced in my original post, so I guess I'll see how well it cleans up! |
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Irving Heavyweight Member
Joined: 11 Feb 2003 Posts: 1887
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Posted: Fri Feb 10, 2023 6:40 am Post subject: |
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It hasn't been mentioned here but red rot usually occurs on the leadpipe and possibly on the tuning crook. It starts from within the horn and eats its way through the brass. The horn you bought looks OK. You can surmise that there isn't any red rot since there are no indications, but when you get the horn look down the leadpipe. If it is smooth like a rifle barrel then it has no red rot. If you can see craters that coincide with brownish spots with a pink center on the outside, then that would be red rot. |
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jeirvine Veteran Member
Joined: 29 Apr 2022 Posts: 337 Location: Baltimore, MD USA
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Posted: Fri Feb 10, 2023 7:22 am Post subject: |
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So does the difference between red rot and tarnish come down to whether it starts internally or externally? I've had plenty of old horns that had obvious red dots on the outside from either water key spray or other external moisture. Often this can be buffed out, but sometimes the dots go a little deeper and will leave a tiny pit.
My understanding is that red rot results from internal moisture causing the chemical de-zincification of the brass from within. Are the two processes chemically/metallurgically different, or is it just a matter of internal vs. external source? _________________ 1932 King Silvertone Artist Bore
1945 Buescher 400
1946 Olds Super
1947 Olds Super Cornet
1948 Couesnon flugelhorn
1951 Olds Special
1956 Martin Committee
1964 Olds Recording
1968 Bach 329 C
1996 Bach 37 |
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yourbrass Heavyweight Member
Joined: 12 Jun 2011 Posts: 3633 Location: Pacifica, CA, USA
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Posted: Fri Feb 10, 2023 7:49 am Post subject: |
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Irving wrote: | It hasn't been mentioned here but red rot usually occurs on the leadpipe and possibly on the tuning crook. It starts from within the horn and eats its way through the brass. The horn you bought looks OK. You can surmise that there isn't any red rot since there are no indications, but when you get the horn look down the leadpipe. If it is smooth like a rifle barrel then it has no red rot. If you can see craters that coincide with brownish spots with a pink center on the outside, then that would be red rot. |
+1
Really advanced rot can be seen on silver plated instruments as bubbles on the outside of the leadpipe or tuning crook. Even so, it can often be cleaned inside and with proper maintenance, it will still last for years. _________________ "Strive for tone." -John Coppola
Edwards X-13
ACB MV3C /ACB A1/26 backbore
https://yourbrass.com/ |
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