My can of paste flux is from Kester and it is so old there are no bar codes, part numbers or anything like that on it. The little can is about 1/2 gone at this point and it still works great. Every now and then I heat up the can a little to melt it all flat again. My dad gave it to me when I was a kid in the 80's learning how to solder, and he got it sometime in the late 60's early 70's. Sometimes old is simply the best.