There's no such thing as 'too long', just leave it in until the dome floats off on its own. If you lightly score the dome with a razor just enough to break the outer skin it can happen in as little as 30 minutes.
I did my first de-dome last night on a Crelant V21A XM-L. I don't have the know-how to remove the whole LED so I just unscrewed the reflector so the emitter was sticking out the end of the light and submerged the top 5mm or so into a shot glass with a little gasoline at the bottom. The dome slid RIGHT off this morning EASY as pie and darn near perfectly.
My only question is how do I get the gasoline smell off?
I ran the head very gently under water to rinse off some of the gasoline and let it sit out all day to fully dry but it still wreaks of gasoline since the metal was submerged somewhat. Obviously I can't really use any chemicals or anything get the smell off...what about just leaving it out in the sunlight? Would that be bad on the bare emitter?
Please use isopropryl alcohol - rinse it - works well with a squeeze bottle. The alcohol is relatively cheap at drug stores (maybe supermarkets too). I use it every time, works well. Actually I use it a ton on cleanups, solder flux, etc...
Should help with the smell, yes I'm think'n, but I can't smell as well as I used to... hhmm, that sounds weird... Well, dunno if it's the same, maybe look it up on wikipedia?
LOL, the flashlight doesn't exist anymore, I put the led in a c8 pill with a 2amp driver as a drop-in for my Uniquefire UF-t20. The test-thrower host is now empty, waiting for a next experiment :-)
You are the one of “pencil beam haters guys” :). I have all types of flashlights.
Well I just want to say few words to you and other guys that are sharing same opinion with you.
There are no thing as unusable light. You just did not find use for such lights.
Pencil beam?
I will give only one example(there are more but I don’t have will for describing). Your flashlight is perfect riflescope reflector light, although I prefer aspherics beam better(I described several times why I prefer aspheric, especially for hunting).
Distant spotting and small size light is very important for this type of hunting. You can not mount bigger reflectors like Olight SR95 TN31 on your rifle.
Your tuned Jacob from picture(you did not have to cut reflector in order to perfectly center the beam) really can throw claimed numbers. It can throw even more than that with XP-E2 with slightly larger hotspot than on your picture.
But really nice job. I recommend only gasoline de doming for XP-E2.
There was someone who mentioned spotting buoys in the night when on a boat, pencil beams reach far and do not put out distracting light nearby. So there are indeed one or two applications, so I'll change my opinion of pencil beam flashlights to 'fairly useless' . Did I also mention that they are fun? I think that 'useless' and 'fun' are very close to each other .
I live in California where the gas has lots of additives so I use white gas (Coleman stove fuel). It doesn’t smell as much. I grind down the SinkPAD if it’s going into a pill that only holds a 14mm then reflow on the LED. I had LED’s slide off from the heat melting the solder from grinding. I then put them in a small jar of white gas for at least 24 hours up to 7 days. Bump the dome with a tooth pick and it falls off. After an hour I test it with a small cell with test leads to see if it works, solder it into a light and burn off the smell.
I think that you are not serious man talking like that. But you are from Amsterdam so that is ok
Fun? If you call 600-800 meters distance spotting fun than fun it is. For me this is some serious fun, joy and need.
To carry one small Nightmaster V2 in jacket pocket or 1,5-2kg flashlight with belt around my neck :Sp?
Not to mention that you will see further in the night with such flashlights. KCD values sometimes means nothing it is important what you can see in the night.
Well city guys in their suburbs really don’t need such flashlights I will admit you that but you would change your mind on “pencil beam” on one of my live presentations of flashlights.
Rubum:
Don’t do that. U can never get rid of smell like that. I know because I tried. Use Isoproply alchol emitter bath after de-doming. It kills any gas smell + it cleans surface.
Yes, for me as a city guy I never need a flashlight, the last power cut here was 10 years ago and if you look at satellite images at night you can see that in the Netherlands there is no place where it ever gets really dark. So for me flashlights are a hobby and I like to explore the limits of what can be made of them, and the concept of really needing a flashlight is quite alien to me, I am quite (but happily :-) ) surprised if anything new that I build is actually something very useful for someone. So thanks for pointing out the usefulness of pencil beams, it makes the hobby even more fun knowing that .
Well, dunno if it's the same, maybe look it up on wikipedia?
. Did I also mention that they are fun? 
I think that 'useless' and 'fun' are very close to each other 
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