A discussion on this forum about zinc in COWWs got me concerned. I, being a rooky, had heaped a large stainless steel stock pot with "sorted" wheel weights and smelted them down. There was a crumbling zinc WW among the clips that I skimmed off the top. I was concerned that if the one I found on top was already crumbling maybe there were more beneath the clips that had melted into my alloy. I remembered an article on Los Angeles Silhouette Club's web site on Specific Gravity http://www.lasc.us/Brennan_3-2_BulletCastingMetals.htm) so I followed the directions and my sample came in at 11.06 SG so I am think my alloy is pure COWW. Being a tinkerer I had to build a spread sheet and a calculator to break the Tin and Antimony percentages down to 0.25%. I found another website (http://www.uslink.com/~tom1/specific-gravity.htm) that had a page titled "How to Determine Approximate Specific Gravities of Alloys."
Inspired by Joe Brennan’s article and following the instructions on "How to Determine Approximate Specific Gravities of Alloys” I developed the attached spreadsheet.
I am not sure of the total value of it but it was fun to build and I think it proved that my alloy is zinc free.
If the SG of your COWW alloy calculates in the 11.07 to 11.00 range you can be confident that you have a pure COWW alloy. When you find your estimated alloy the % of tin and antimony can be read directly on the chart. To determine the percent of lead you will have to subtract the amount of tin and antimony from 100.
None of the cells are locked so you can clear out all the data in the grey cells and replace it with your own. You can also clear out all my color formatting. I only put that in so you could easily see the results of the samples I included.
Have fun, if you find any errors please let me know.
Specific Gravity Calculator.zip
Al
|
   
   
|
|
Reply With Quote
Originally Posted by bumpo628
