Is that the Sharkskin paper? If so, I used it routinely for filtering values from polishing wastes. I agree---it was a paper I couldn't get along without. I didn't prefer it otherwise, concluding that it allowed too much to pass through the filter.goldsilverpro said:The best general purpose filter paper I've ever used for refinery operations is S&S 596.
I agree-----it allowed far too much to pass through, but when separating solutions from polishing waste, it had no equal. It was the only place I used Sharkskin, and found other papers would fail miserably. The strength of Sharkskin placed it well above anything else I ever encountered.goldsilverpro said:No, it's not S&S Sharkskin. It's much thicker. In a pinch, I've used a lot of Sharkskin but never really liked it.
My experience parallels yours. I used 42 only with a Buchner. Virtually all of my filtration was done by gravity, using Nalgene funnels that accepted 32cm circles.I started with Whatman 42. It's very retentive, slow as molasses, and quite expensive.
I agree, they were not cheap. I paid in excess of $50 for a box of 100 32cm circles when purchasing the Whatman #5. Whatman #2 was less expensive, around $30 for 100 circles. Considering the cost for filtering what was often several thousand dollars worth of gold, I wasn't the least bit concerned with the price. What did concern me was the end result, and I was never disappointed with Whatman. Assuming their formation remains unchanged with the change of ownership, I'd recommend them today.I have used many of the Whatman papers, but never liked their prices.
Heh! I folded my papers and used gravity with a Nalgene 60° funnel. I should have made that clear. My largest Buchner was something like 24cm, and I'm trusting to memory here. I found that if I did the proper preliminary work on my wastes (incineration accompanied by a wash with HCl), I had no difficulties filtering solutions. I could filter a huge volume of gold chloride (as much as 75 ounces in solution) easily in a day, usually far less. That's using a Whatman #5, which was dreadfully slow and retentive.Lou said:This is why I use the fritted glass disks--they're expensive, several hundred dollars depending on the specifications, but it is a one time expense. Harold, I too have a set of 32 cm Buchner funnels but I find myself using the frit filters (only 12 cm across) because they are far more convenient in removing the precipitate, no worries about contamination, and much cheaper in the long run.
That might be interesting for readers to see. I know it holds my interest. I experimented more than enough before landing on my choices--and am secure in the idea that Whatman provided the best filter papers, at least for what I was doing.I have somewhere on one of my computers a PDF of all the various different filter papers Whatman makes. If I can find it, I will be sure to attach it to this thread.
butcher said:Why not just dissolve the gold (putting the filter in solution), then filter this decanted solution, pouring the old filter and insoluble salts in the last stages of this new filter.
Sometimes adding shredded filter paper to a filter can improve difficult to filter solutions.
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