Mysterious Polishing Problem

[Aurarius]

I've just used the Firescoff on a plain band in sterling made from 4mm by 2mm D-wire, size R.

I'm pleased to say that after polishing there is no detectable firescale. This surprises me really as the coverage I achieved with the Firescoff was by no means uniform; it didn't form an even coating and instead just sat on the ring in a series of droplets. I did degrease the ring and I think the reason for not getting an even coating may be that I hadn't warmed the ring enough before applying the spray. The reason I didn't warm it much was that I didn't want any oxidation through heating to occur on the unprotected surfaces. Maybe I was unnecessarily anxious on that score as maybe oxidation only really starts to occur at higher temperatures (i.e. much higher than the 150 degrees the instructions recommend you heat the metal to before applying the spray). I don't know the answer to that one, I'm afraid.

Another reason I'm surprised I got no firescale is that I was working with my Proxxon torch again, and, as before, it took about three minutes to get the whole ring up to the temperature where the solder (hard) flowed. This is not ideal, I know, and I'm on the point of buying a bigger torch. I've combed the threads on here about torches and a couple of questions spring to mind before I make a decision. I'll ask these in the relevant threads.

Thanks to everyone for the help with this problem. It's been invaluable.

[Dennis]

It looks as if you will be an ambassador for Firescoff. Yes for fluxing evenly the metal needs to be warm, but the copper oxide which is firescale does not form until you see a glow. Dennis