Can't believe I'm going to say this, but I got this snippet of info from the bitchfest that is STW:
But if you want to be sure, weigh the spring, then fill a suitable container to the rim with water, drop the spring in the water, and weigh the water that's displaced by the spring.
Divide the weight of the spring by the weight of the water, if you get a number around 4.5 then its ti
I'm off for a wash