I recently posted a link for a spreadsheet I wrote to calculate the ppm of homemade CS. "Ole Bob" was kind enough to offer to test samples I made, and compare his lab results to the predictions of the spreadsheet.
Well the the results of the Ole Bob test are in, and Im sorry to say they were rather disappointing. As Guenter suggested, Ag depositing on my cathode had a significant impact, one that I failed to take into account. I hope to compensate for this in future versions of the ppm calculator. Ole Bob and I discussed the results and here is our conclusion: The ppm calculator spreadsheet uses Faradays equation to calculate how much Ag is liberated from the anode. It does this accurately, but not all of the Ag liberated winds up suspended in the distilled water. Some gets deposited on the cathode, so the actual ppm is going to be less than the calculator predicts. How much less depends on several factors. Bob and I believe that the most important factor is the surface area of the cathode (size of the anode is not relevant here). Unfortunately, I used rather large cathodes when generating the samples I sent to Bob for analysis. Time is also a factor; the longer current flows, the faster Ag seems to plate to the cathode. So shorter brewing times may result in more accurate ppm prediction than longer brew time. Bob and I hypothesize that a cathode with very little surface area will not allow significant amounts of Ag to plate, and so the ppm calculator results would be reasonably accurate. We intend to test this hypothesis, hopefully by the end of this year. We will post the results. Bob noted that since high voltage CS is not as prone to plating, the spreadsheet results may be much more accurate for HVCS. Ive asked him to test this if he has the opportunity. But most of us low-tech types (myself included) use low voltage (under 40V) and I hope to find a solution for us. ----------------------------------- Here are the samples tested, and the results. I brewed 3 batches of CS in varying concentrations. Each batch was made using a $1.49 Radio Shack stirring motor, and current was limited to a maximum of 5.5mA. Electrode spacing was about 1.5 inches. Sample A = 3300ml distilled water, 36sq inch anode, 10sq inch cathode Spreadsheet predicted 16.6ppm. Lab test result was 9.02ppm (45% deviation). Sample B = 3300ml distilled water, 36sq inch anode, 10sq inch cathode Spreadsheet predicted 12.3ppm. Lab test result was 7.92ppm (36% deviation). Sample C = 700ml distilled water, 20sq inch anode, 5sq inch cathode Spreadsheet predicted 7.1ppm. Lab test result was 5.72ppm (20% deviation). ----------------------------------- While this information is useful, Im disappointed. I was hoping for accuracy within 10% or better. As I said before, we have a hypothesis to test, and well keep the list informed. It may be a while, though. If everyone used the exact same generating setup, it would be relatively easy to plot the deviation and modify the equation to compensate, making the spreadsheet accurate. But generating setups are as individual as the folks who make them, and my goal is to allow everyone to use the setup they prefer and still get accurate results. Its possible that if you are using a cathode with relatively small surface area, for example 14 gauge silver wire, the ppm calculator will give you fairly accurate results, better than those above. Try putting only 1 inch of your cathode in the distilled water, in order to minimize its surface area available for plating. Ill be testing this method myself, and will post the results when theyre available. If youve downloaded the ppm calculator spreadsheet, and you want to be notified when upgrades are available, email me at cs_share@ yahoo.com and Ill send you a note when I post a new version for downloading. You wont end up on any other mailing lists, and like the original version, any upgrades I make will also be free of charge. Im not doing this for money. The spreadsheet may be downloaded for free at http://briefcase.yahoo.com/cs_share/ My heartfelt thanks to Ole Bob for analyzing my samples, and for his advice and encouragement. And thank you to everyone on the list who tried the ppm calculator, and especially to those who wrote to me. __________________________________________________ Do You Yahoo!? Yahoo! GeoCities - quick and easy web site hosting, just $8.95/month. http://geocities.yahoo.com/ps/info1 -- The silver-list is a moderated forum for discussion of colloidal silver. To join or quit silver-list or silver-digest send an e-mail message to: silver-list-requ...@eskimo.com -or- silver-digest-requ...@eskimo.com with the word subscribe or unsubscribe in the SUBJECT line. To post, address your message to: silver-list@eskimo.com Silver-list archive: http://escribe.com/health/thesilverlist/index.html List maintainer: Mike Devour <mdev...@eskimo.com>
