I thought about the steamer residue but I haven't heard of "tinning". Can you elaborate on this technique?
Tinning referrs to the application of solder to one side and perhaps the
other, prior to joining two pieces. for example, if you wish to solder a
piece of half round to a flat sheet and don’t want to have to clean up the
mess, you first sparingly apply some solder to the flat side of the half
round, not necessarily the full length, and then place the "tinned " half
round on the sheet. By heating the sheet, the solder will flow to the
sheet and already is on the half round. You probably already do this with
earring posts, that is pick up a bit of solder on the post, and then heat
the earring back, and then touch the post to the back. The solder flows
and makes a tidy bitty dot and no more.
Tinning is the term used by plumbers to applying “tin” but really soft
solder to the pipe prior to joining.
Judy in perfect weather in Denver, it doesn’t get much better than this.