RotoMetals Popcorn Tin - BE CAREFUL!!
Since I started adding 2% tin to my COWW lead I've been on the search for inexpensive tin. I know, I know, there's more than a couple of you who are going to advise me to find cheap pewter but I just don't want to go around scrounging for an unknown. 97/3, 64/40 etc. solder is a convenient source if you don't mind getting nailed $40 per pound for tin but after using 97/3 to get myself familiarized with adding tin I needed to find a different source than the local Ace Hardware. This of course led me to RotoMetals and through them a new product that they have that they call Popcorn Tin. I ordered a couple of pounds a few weeks ago ($20 per lb) and have since run through about a pound of it. Here's what I think....
The big advantage to the Popcorn Tin is that it weighs well on a small digital powder scale and you can hit your exact weights easily simply by adding tiny pieces of the product. There isn't any need to error on the side of too much tin since it's so easy to weigh. The price is about a dollar a pound more than their cut wire tin. For the ease of weighing I think the buck a pound is probably worth it but there is a SERIOUS down side that I found.
I don't know for sure but I might venture to guess that they make their Popcorn Tin by water dropping molten tin. To me that's what the finished product looks like at least. As you might have already guessed, there is the possibility of trapped water in those little popcorn kernels of tin. So far after using almost the first pound of Popcorn Tin I've encountered two pretty substantial bangs when adding it to molten lead. As of yet I haven't had a notable visit from the Tinsel Fairy but I'm more than a little sketchy when adding to molten lead. Of course the quick answer if using this product is to NOT add it to molten alloy but when the pot is low and you want to keep going it's a pain to let everything cool off, solidify and start over.
I'm posting this for informational purposes, if there's any of you out there who are using Popcorn Tin I'd like to know if you've had similar experience with it. If you're not using it and are thinking about it just be aware that it appears that it "can" harbor some trapped moisture that could lead to surprises.