So I assume we all know that for simple little springs that don't have to move very far - mostly box releases etc - you can take some mild-ish steel and cold hammer the heck out of it to get some work hardened springyness. Of course you can do the same with brass too if brass springs are your thing. But I've been using some little scrap cutoffs of really old salvage iron which apparently has a negative carbon content, and even beating the $#@* out of it to thin it out will not render it springy in any conceivable way. Just for giggles I made up a semi circular spring for a box release I'm currently making, all crude and attached to the inside of the buttplate, and I heated it up pretty darned bright orange and dunked it in kasenit a couple of times, then water quenched. I did then draw it back to a light blue. And gosh darn it, it's springy as all get out. I'm going to assume that because the springy portion was hammered out very thin (probably only @ 1/32") that the kasenit and multiple heats seems to have converted a good portion of it to a steel with enough carbon to actually work as a spring? Don't know but it sure does work well with a lot of flex available, and bounces right back.
This is real kasenit btw, I don;t know what else is comparable now that it's off the market.
