I am of the opinion that what contaminates gold is more important than the percentage. For example, according to Hoke, even traces of lead will destroy its properties, whereas it readily alloys with silver and/or copper and retains respectable ductility. Were that not the case, gold leaf would not be possible unless it was of pure gold.
I also believe that oxides are far more damaging than are pure metals, so it's entirely possible that a wide array of things bring down the quality of gold, each of which likely manifest themselves in limiting its ability to form a respectable pipe.
To be perfectly clear, most folks likely don't like seeing the pipe---it disrupts their stereotypical idea of what an ingot should look like--but, as I said, to those that are informed, it's obvious that gold that has pulled a deep pipe has high purity. You can see that yourself when you examine the pipe---note the rich color that results from the light reflecting from side to side. You don't get that from dirty gold. It just isn't there.
I was obsessed with purity when I refined---it was for that reason I built a Wohwill cell (although I never put it to use) and went far out of my way to refine my product a second time. The reward, for me, was the resulting beautiful gold---although I must confess, I enjoyed the trust that developed between me and my customers, all of whom enjoyed the high quality.
Harold
