Putting a XP-G in gas oil for 24 hours works fine.
The dome did not fall off by itself though. What happened was that I thought it had not worked so when I took it out of the gas oil i poked the dome with my finger to feel if it had gone soft at all. It had not really but it just slid off!
I then sprayed the die with electro cleaner for a few seconds and that removed any gooey stuff that was left.
Initially worried that I might have broken the bonding wires with my thick fingers I hurried to test it out with a battery and it works.
Thank you very much to the OP and all others who have contributed to this thread and the knowledge we now have. TY! :-)
I found here on a dutch forum that an electronics guy used petroleum-ether to remove silicone remains. I have some here where I work, I will give it a try. The composition is not far from gasoline, but it is much cleaner. It is even more equivalent to Coleman Fuel (which is also much cleaner than gasoline).
I doubt that it will work. It is a pretty mild solvent. Good on sticky residue from tape and tends not to harm most plastics. I use it for polishing plastics and LED display windows with red jewelers rouge.
The petroleum-ether I have here says: 100-140°C. I may have some Coleman Fuel as well somewhere. Perhaps when I can find some time and enough spare leds I will do a 'great dedome test string' one of these days..
I never had any luck with the XRE twist, always some bad residue left behind. And removing those always a mess. My success rate is only 33%, 1/3 - one ruined wire, one bluey, and one not-so-good-but-I-leave-it-alone-anyway-otherwise-rate-would-be-0/3… heheh.
With petrol soak, the whole ring and dome just slid off. I have 100%, 1/1 success on this method for XRE. Best, cleanest result out of the four too.
LOL, I’ve got a zoomie with that problem already from a thick hold down ring - the ring reflection is outside of the beam, but still wanting to paint it black.
No, I’ve got a spare XRE and if I de-dome the ring will go even if that ruins the emitter.