I was gifted a full 1lb roll of solder over the weekend. The box says "Sterling premium quality lead free solid wire solder". Backside of the box says "contains tin, copper and selenium", but it doesn't give a percentage of anything. My question is can I cut a 3-4 inch piece of this and add it to my COWW to up the tin percentage without contaminating my alloy? I'm not even sure what selenium is.