Removing Solder Residue from Brass Instruments: A Restoration Guide

Question
Dr. Roark,

This question is not dealing with jewelry but i think it may be in your area of expertise.

I am refurbishing an old brass instrument.  I needed to re-solder some of the brackets and as a result of some minor repositioning, there is now a "tinning" from the solder in spots that no longer have a bracket (but used to).

Is there any way to remove this tinning so that the brass in these areas shows again?  It will just be a much neater job that way.

Thanks,
Rich  

Answer
Removing it is as easy as heating it and applying some desoldering braid - radio shacks sell it in a coil at about 2 bucks.It's a great thing to have on hand. Just apply some yellow ochre ( jewelers supplys and art stores sell the pure pigment powder, it is mixed with water to make a heavy  cream weight  liquid ) to the area you don't want affected ( the join), then heat the area and  apply the  braid.it will soak up the excess  solder  which is part tin, and  zinc and silver  and in the case of yellow silver solder ( hoover and strong, rio grande)There are also vacuum tools ( american scientific and surplus has one on sale  at the moment: http://www sciplus.com) that suck up the excess.
As far as simply scraping it off with a jewelers scraper or bench knife, I think it would do more damage than good. The Radio shack soldering braid is the easiest, cheapest way to go. Sal ammoniac is the chemical ( available at stained glass suppliers) that is specifically to  tin or remove tinning from  soldering irons.It comes in a block and one simply rubs the iron over the block to remove the tinning or prep the iron for its first use.
good luck as removing solder is  a hated chore of all jewelers and repairers worldwide!
Happy New Year to you and yours, Ari