Reply To: solder dials and bezels

[Bob Tascione]

Hi guys,
I just had this problem with one of my own clocks a couple of months ago. There are a few tricks you can try which seem to work well for me. There’s a good chance that the dial pan is zinc. Problem with zinc is that it forms a zinc oxide when heated which puts some kind of barrier between the solder and the plate itself…I don’t know much about how this stuff works so I’m sure there are many who can elaborate on this. Anyway, one thing that I do know makes a big difference is the prep work. Surfaces have to be EXTREMELY clean. I remove all old solder completely and then wire brush down to shiny metal leaving the surfaces rough and clean. I also use a liquid brush on flux. Paul’s exactly right about using low melting point solder! Silver solder requires more heat than regular Tix or 60/40. I had absolutely no luck at all using silver solder! It just rolls around and laughs at me. I think TIX and 60/40 are made up of both lead and zinc so maybe the zinc content makes a difference when sticking to the zinc pan…just a guess though. Also only use a soldering iron and NOT a flame. I use a Weller with a chisel type tip. If the surfaces are super clean and you use the correct flux and low melting solder the solder will spread and follow the flux and the temp won’t be high enough to cause any damage to the paper dial. At least that’s been my experience. I don’t put much solder at all and only flux a small area for the solder to follow as I want the solder to sort of melt and sit there as a small dab with a little height rather than spread out into a flat surface. I find that the height is needed because the normal gap is sometimes pretty large between the two surfaces
being soldered.

Hope this helps William!
Good luck and let us know how it works out.
Bob