Raising Copper on 18k Soldering

Hi all,

I’m having a problem with the copper in my 18k alloy coming to the
surface of my work in the process of soldering, and I’m wondering if
anyone could tell me how to prevent this, and how to get rid of it
once it happens.

The elements: I’m using 18k yellow and occasionally green gold from
Hauser & Miller, oxy-propane setup with a Smith versa-torch
w/mini-torch attachment, HandyFlux paste flux, and 18k plumb gold
easy solder (1470 degrees melt & 1530 degrees flow), Sparex pickle.

Is it my flame? Is my pickle too strong? Do I have a bad batch of
gold? I’ve tried adjusting everything, and I still seem to be raising
enough copper on, for instance, 18k jump rings that I’m soldering
shut, that in the end, they actually look like copper, and not like
gold anymore.

Suggestions?

Thanks in advance,
Sarah