ACB Mini-Lesson 66 (pardon the typo on the screen): Red Rot and Valve Compression

[Links in description] I love vintage trumpets and have many in my own collection. Some of the coolest designs (and best sounds!) are found among older instruments. But they can have some problems as well. The issues we see most often with vintage horns are poor valve compression and the dreaded "redrot." Here's how to tell if a horn your looking at has one of these issues!
1:35 What is redrot? It's the process of "dezincification," which is the process of acids from saliva and food particles start breaking down the inner surface of your leadpipe and tuning slide. The telltale sign is a small round spot with a little nipple-like indentation in the middle.
3:00 Surface pitting is a different form of wear, that is not the same as redrot. It may still be a very round spot, but it won't have that little nipple in the middle.
3:28 Once redrot starts, it's an irreversible process. Eventually you will need to have the leadpipe replaced, which is not always the easiest thing to do on a vintage horn from a company that might not even be in business anymore. So how can you prevent redrot?
3:42 1. Swab out your leadpipe after every time you play, with a product like the HW Brass Saver www.austincust...
4:14 2. After the leadpipe swab I use a product I absolutely love called BlowDry Brass. If you start with a clean horn, the BlowDry Brass system does a very good job of keeping the horn in a clean state (when used consistently per instructions): www.austincust...
5:30 Both of these products are much cheaper than replacing a leadpipe!
If redrot does cause a hole in your leadpipe you'll either need to replace the leadpipe or have a patch applied by a repair shop. We test horns with a compression measuring machine here at the shop to make sure that any spots of redrot have not turned into a hole.
6:04 Next onto valve compression. We have a fancy Magnahelic gauge here at the shop to measure compression, but you can do an informal check yourself at home.
A couple words of caution:
6:45 1. You can't tell valve compression by looking at the pistons! The pistons could look absolutely fantastic and still have poor compression. Compression is based on how tight the pistons are in the casings.
7:01 2. The "pop test" is not an accurate way to check compression! A slide might have a loud pop in spite of poor compression.
7:10 Here's how to really check compression. Remove the valve slide and hold down the valve. Cover the end of the pipe fully with your finger. Blow into the leadpipe. Hear any air leaking? If you can, that's an indication of low compression. Another good test is to play loud low notes. A horn with bad compression will lack centering and slotting in loud low register playing.
8:28 A horn with low compressions will also have much wider slots and easier bending of notes. Some people prefer horns with lower compression for this reason! There's a lot of room to maneuver. Of course you can also get new horns with less defined slotting, like the Adams A9 or the Adams A4. I tend to like more defined slots, but it really comes down to personal preference.
"So my horn has low compression, but I don't want to spend hundreds of dollars on a valve rebuild. What can I do?"
9:30 Try is a thicker valve oil. The heavy oil we use at the shop and recommend often to our customers is the Berp Bio Oil #3: www.austincust... If compression isn't quite as compromised, there are several other great options as well, like Hetman #3 (www.austincust...) and Ultra Pure "Black Label" Classic (www.austincust....
9:52 You can also add a couple drops of spindle bearing oil to the pistons as well (don't overdo it) to help increase the seal. If you want to see if your horn as VERY poor compression, you can try a thin coating of 5W30 or 10W30 motor oil on the pistons. The valves won't move, and you'll need to clean the horn very well after this test, but you'll be able to play the centers of the notes. The tone of the horn may sound dramatically different.
Post your questions, comments, and yeah-buts in the comments below! Is there anything you want to know about trumpets, or playing them? Let me know, and your idea may be featured in a future mini-lesson!
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