I've been using solder salvaged from a radiator shop; floor scrapings. The owner claims he uses 60/40 exclusively. In the reclamation I started with 1 and 1/2 , 5 gallon buckets of scrapings. At finish I had a 2 lb coffee can filled with ingots and all the remainder was dirt and filth.
Although the ingots work well, using them in common published proportions with wheel weights to increase tin content of the boolit alloy does not produce a metal of expected hardness, normally being several points softer than might be expected. Neither does it oven harden to an expected level of hardness.
The ingots test at 10.5 on my Cabine Tree tester.
Does any one have an ingot of factory produced 60/40 solder they might hardness test for me as a comparison?
Given the high percentage of dirt removed from the scrapings and the amount of heat required to separate the solder from it I am wondering if a significant proportion of the tin in the original solder oxidized and bonded with the dirt. Although I fluxed during the process I wouldn't claim it had any great effect due to the huge amount of crud in the pot which made stirring the flux down nearly impossible.
All input gratefully received.