During the smelting of WW I thought it might be a plan to have some tin or maybe 50/50 solder on hand. Once the WW are molten, fluxed and ready for the ingot mold the appropriate measurement of tin could be added to the mold (muffin tin in my case). This would give a WW + 2% tin alloy. When the ingots are melted for casting the alloy should be correct? No need to play with the alloy of the melt while casting. I haven't been really exact in my addition of tin, so far, so this method may help out in the percentages precision. Just a thought. Does this sound reasonable or am I missing some tech knowledge that would make this a poor idea?