Posted by Chuck(G) on March 13, 2003 at 12:08:53:
In Reply to: Do cracks/holes in bells NEED patching? posted by Mr Bent Bell on March 13, 2003 at 11:06:26:
A good post from Dale.
There are several other things to consider.
If your instrument isn't silver-plated, a silver-brazed joint will show a difference in color--silver braze is not brass-colored. This can be quite minor and may or may not be of concern to you. It is possible to brush-plate a very thin layer of brass over a silver-brazed joint to create a closer match in color after the bell has been buffed, just before it's lacquered. The brass thus deposited is only molecules thin, so it would not be suitable for a raw brass finish.
It's not advisiable to silver-braze very thin metal, such as is found on the edges of bells of some Bohemian and Czech instruments--there's a danger of oxidizing the very thin brass in the higher heat needed to silver-braze. A patch will also be stronger in this case.
If you have a crack or hole in an area not visible to an observer--say, on the player's side of the bell near the rim, patching is still a good option. A patch applied to the outside of a bell, with edges properly feathered can be made to look almost invisible.
Once soft solder has been used to patch a bell, it's more difficult to silver-braze it, as all of the original tin-lead solder must be thoroughly cleaned from the joint, lest it contaminate the silver braze.