I dont know if it helps but aviation fuel here has the highest octane rating and still has lead in it. If using this method it would be highly advisable to not have any ignition items close by near the fumes and that includes any naughty people that still do this, smoking.
@AlexGT: accidentially left an XPG in gasoline for 3 days. Didnt hurt the substrate.
@OL: Octane rating was 95. Thats the lowest we have in Germany. Thanks for your concern, but no worries, I always test my schnaps with a lighter, if it burns, I dont drink it. :P
@vesture: Gasoline with 95 octane vaporizes without any residues. And people did such tests.. you lose about 20-30% lumens but gain a lot lux.
@MRsDNF: We only have lead free gasoline in Germany since about 15 years.
Also, there is a difference between acetone and gasoline. Acetone dissolves the dome faster but not completely. Gasoline takes considerably longer but completely cleans the LED.
Thanks for this info. Hope I can remember this when I start my next mod. 
Thnx for the info guys!
How much ± tint do you lose when dedoming? If you want to end up with a 5000K colour after dedoming, what what tint do you need to start? 0A/0D/1A/1D?
If you dedome a XML 1A and you dedome a XML 3C, will they have the same colour, or will the dedomed XML 3C be warmer than the dedomed XML 1A?
Thnx
Rough number: you move two numbers up. 1C->3C. 1A->3A. 0D->2D.
Not always, but thats exact enough for me.
Thanx for all these info. I’ve just removed the MPCB off my K40 and it is now being ‘marinated’ in gasoline. I’ll leave it in a safe place and observe the results tomorrow as its almost midnight here. I just hope I’ll get positive results. 
I’m gonna boost the throw of my K40. J)
I wondered if you could buy them de-domed as well. It would be great to get de-domed emitters direct from Cree! It would save them having to put the domes on in the first place…
Or we can ask them to make flat domes lenses, protection for the phosphor and same results than dedomed