The higher temperatures for lead free solder is my problem. The leaded stuff allows my marginal solder gear to work better. I took home a 16oz roll of Kestor 60/40 from work 35 years ago, and it should last the rest of my life. except I keep misplacing it. I had to run out to get the new stuff that didn't work. Now I have a 12oz roll of Austor for when I can''t find the other roll.