Oops.
After finishing soldering my Very First model airplane fuel tank, I went to do the last step of any soldering project -- cleaning off the flux.
Unfortunately, while I know that the flux I use yields to scrubbing with hot soapy water, I don't know what -- if anything -- will just take it off. I'm experimenting.
I've got some in each of four cups, with lacquer thinner, mineral spirits, isopropyl alcohol, and plain drinking water. None of them seem to be having any effect except the mineral spirits, which appears to be separating it into two components.
In the mean time, I'm checking here to see if anyone has any pointers. It's "Top Line Quality Soldering Paste Flux". Bought over thirty years ago (I don't go through flux very fast). It looks like bearing grease, & it sizzles when the iron touches it. Works great, but leaves a residue which I don't want inside my engines!
So -- anyone happen to know if there's a common soldering flux that contains calcium chloride and has this consistency, and if so how to clean out the inside of an itty bitty fuel tank made with it? If all else fails I'll run really hot water through it along with dishwashing detergent -- but that doesn't leave me 100% confident.