I recently bought this on ebay for 27 dollars. An OLDS AMBASSADOR model cornet made at the 1950s. A high quality instrument, although being a student model, is known to be also used by many professionals as well because of its tone quality, durability etc.
It was a mess when i received it, very well worn, its lacquer completely gone, valves were not oiled for at least 20 years and very sticky, slides unable to move. Instrument was most probably left and forgotten at an attic or basement for 20 years or so.
Solder at three big joints were ripped off and as the support provided by those joints was lost, the instrument was bent during storage. The leadpipe was not straight as well as the bell pipe and bow.
Step 1: Preparing the Instrument
First I've removed valves and slides from the instrument. The slides required a bit heating to be removed. Then i did a good detail cleaning. Used the torch and some soldering resin to further clean the joints to get them ready for soldering.
Step 2: Straightening the Instrument
I've corrected the bell pipe and leadpipe by carefully applying pressure by hand first.
At places where a more steady and slow movement is needed, I've used steel wires, wrapped them around the instrument, connected the two ends of the wire together and and turned that end with pliers slowly, tightening the wrapped wire, so squeezing the area of the instrument where the wire loop is wrapped, pulling parts of the instrument together, making them move into their original positions. I've used some wood sticks to spread the applied force evenly over the soft brass tubing to prevent them being dented by the wires.
I've also used some allen keys as leverage while correcting and aligning some details, like points that require resoldering.
Step 3: Check Whether You Know How to Solder or Not.
I didn't feel %100 confident for soldering a musical instrument with a history. So i did some exercising, first on purchased brass tubes, by cutting them into different shapes and lengths and randomly soldering one an other. Then as a bigger experience I made a small bicycle frame. Then as a last test, I've did some soldering on an older trumpet with some loose joints.
After already having done a lot of circuit soldering as an electronic hobbysit and engineer for 30 years, my soldering learning curve was short fortunately. After a short while of exercising and experimenting, I felt like ready for the job. This learning phase should normally take longer. Soldering big metal parts with a flame is a dangerous and difficult task to do and requires some experience which is only gained only by doing more soldering. Take your time, do not hurry or be sure you'll destroy the instrument.
Step 4: Time to Solder the Instrument.
The key to this kind of soldering is to be careful and slow as you'll be working with a powerful flame. Other types of flameless soldering irons, guns etc would most probably be too weak as the areas & parts to solder are big and the instrument itself also acts like a radiator, taking heat away from the point being soldered. So something strong is needed.
A hand type torch did the job for me. The soldering took a bit long as even this torch is a bit weak for this kind of job.. But I guess it is better this way, as it makes making mistakes a bit more difficult also.
I've bought soldering wire a bit thicker than electronics soldering wires. This one I bought has 2.5-3mm diameter.
I've also tested the electronics soldering wire, it is too thin. It melts and drips to the ground, just at the moment it gets a little close to the flame, without even touching the point to be soldered.
The sequence of soldering for me is as follows;
1-Clean the area of solder, by sand paper if possible. If too tight for sand paper, a thin metal tip or small blade can also work.
2-Heat and apply soldering resin.
3-Continue heating for 15 seconds or so.
4-Point away the torch and simultaneously touch to both of the surfaces to be soldered with the tip of the soldering wire and push it into the gap, trying to melt it with the heat of the metals as it goes in. If it doesn't melt this way, either try a thinner soldering wire or get the flame a bit closer while pushing the solder wire in.
5-Do not put on too much solder at once, melt small drips and let them flow into the broken joint, filling the gaps.
6-Slowly rotate the instrument while heating to let the liquid solder to flow towards where you want it to.
7-When the bond seems ok, cool & harden it with a spray of water to prevent solder to flow out of the joint.
8-Do not hesitate to heat the instrument as it is not possible to do soldering without the surfaces reaching the necessary temperature. But do not exaggerate, some other soldered parts of the instrument may become loose or the lacquer layer may burn. Be careful and heat only where heat is necessary.
Step 5: Soldering Complete, Time to Do Some Cleaning and Polishing.
I've soldered all three loose joints. I wanted the joints to be as strong as possible, so I've used a bit more solder than just adequate. It is always possible to file away the solder blobs with a dremel later.
I've removed wires etc, again did a surface cleaning, removed some solder blobs here and there dremel or hand.
I've bought some metal polishing cream and some polishing cloth for giving the instrument a nice shine. The cloth is like a 2cm wide ribbon. After experimenting, I saw that wider ribbon could have been better and easier to use in some areas. So go get both types, 2cm for polishing narrow areas-gaps and 5cm wide for wider spaces. Even a wider ribbon can be helpful for polishing the bell area.
The job sequence is;
1-Apply some metal polisher to the surface. Try a small amount first, then adjust the amount as you experiment.
2-Rub without excessive force and with high frequency reciprocal movements, with speed.
3-Goto step 1 until the surface is shiny enough for you.
do not forget to wash the instrument inside out after the polishing is complete to clean off the remainder of the polishing cream, if it gets into the valves, can cause damage due to abrasion.
The case had a musty moisty smell as well. To get rid of this smell I've mixed some carbonate into water and stirred to melt it all, then added more carbonate until it accepts and melts no more. Then I've used a water atomizer-sprayer plastic bottle to spray this carbonate diluted water into and around the case. I got every part of the case quite wet. Then left it in some warm place to dry. Wit this method the smell goes considerably. If you feel it is still smelly, repeat this procedure. Once was enough for my case.
One thing to be very careful. DO NOT spray the carbonate solution over the cornet-trumpet. If the solution accidentally touches the instrument, completely wipe it out with a cloth. OR it will damage the surface of the instrument. And DO NOT put the instrument back to its case when the case is still wet. or the instrument will get damaged the same way.
Step 6: Seems Like It Is Time to Play.
Reassemble the instrument
and go practicing.
happy playing :)