Great shots there Aardvark, all you need now is a 589 to add to your collection! I'm assuming also you've never been 'apprehended' when taking these shots in public?
Please be careful with Teflon tape. Small fragments can find themselves on the exposed diode window leading to contamination and potential damage; a good tip is to only wind the tape half way down the lens barrel and not to continuously alter the focus which will cause the tape to shred over time.
I have never used that specific brand although I understand these treatments are basically hydrofluoric acid mixes which are highly corrosive. I decoated some glasses lenses a few years back (plastic) with good results. However I have heard that the acids used in this stuff can possibly...
Just 'Sharpied' my thumb and yes my skin will sting after a few seconds. Also, tried to light a black match with the aid of a focus lens and it managed to fizzle three times but not quite ignite. Must get an LPM. For now, a quick pic in a dark room without the aid of fog.
I think the skin test can vary considerably based on your skin type. A darker skin or sun tan will absorb more heat than that of a pastey Englishman for example :) Look forward to the pics!