Thanks for starting this thread VNinja, the perfect wick is the holy grail of vaping. I think any wick material should be assessed for the following properties:
1. Capillary action (obvioulsy). How well does it wick and is its wicking ability durable? For example, Raidy, the inventor of the Genisis atty, abondoned porous ceramic early on because it clogged easily, maybe the FC-2000 is better in that regard.
2. Electrical resistivity, the greater the better, nobody likes shorts.
3. Thermal stability. Does it burn or otherwise transform chemically under repeated thermal cycling or torching during preparation?
4. Structural strength. Does it break easily (porous ceramic) or fragment with time (silica)?
5. Chemical inertness. The more the better. Does it react with pg/vg/nic/flavorings to make new compounds?
6. Safety. This is the most complicated of all and relates to items 3, 4 and 5 above.
For any action taken in life, one must carry out a risk/benefit assessment. Does one outweigh the other? I'm not talking here about vaping vs smoking, that's another topic and one that we have all weighed in favor of vaping because we otherwise wouldn't be here discussing these issues. I'm talking about the risk/benefit assessment of one wick over another. The benefits of one wick over the other are going to be subjective: one person's fantastic vape is going to be another person's "blah" or "meh". The risks on the other hand are theoretically quantifiable, but it will require decades of vapor inhalation exposure and large epidemiological studies to assess with any degree of certainty. The closest thing we have to that now is that OSHA has deemed long term inhalation exposure in workers in the glass fiber (what we call silica wick) and related industries (construction for example) to not pose any significant risk of repiratory illness or cancer. We also know that hexavalent chromium is carcinogenic, that it was found in measurable quantities in the drinking water of 31 of 35 tested american cities (crap!), and that OSHA has deemed stainless steel welders to be at risk.
Otherwise we know squat about the long term inhalation exposure risk to SS mesh, cotton, hemp, bamboo, porous ceramic or nextel ceramic fibers subjected to varying thermal and chemical exposures, and we won't for many years. On this basis, the kind of person who likes the benefits of silica wick well enough and who dislikes the fundamental lack of epidemiological evidence for the possible risks of these other materials, should stick with silica, because at least for that we do have some semi-relatable evidence.
In the meantime, the best the rest of us who are willing to experiment with other materials can do is to try to pool our research efforts and knowledge to assess them systematically according to properties 1 through 5 listed above, and any others that the members come up with.
In this regard, by criteria 3 above, I agree that the hexavalent chromium issue is a big strike against oxidized SS and has soured my feelings for it considerably and since unoxidized is a hassle for me because of criteria 2, I will probably abandon SS completely, unless an obviously safe way is found to isolate it from the resistance wire.
