The MT-G2 doesn’t take kindly to de-doming in my experience, and that is also what others say. It’s very easy to mess up the beautiful tint it has, with no gains OR simply destroy it in the attempt. The phosphor is completely covering the die base, with 72 independent tiny dies lying underneath it. Very often the phosphor comes off those tiny dies and gives a blue or purple tint to the light, meaning too much UV is escaping.
Try de-doming it only if you’re prepared to replace that $18 emitter.
DBCstm wrote:
The MT-G2 doesn’t take kindly to de-doming in my experience, and that is also what others say. It’s very easy to mess up the beautiful tint it has, with no gains OR simply destroy it in the attempt. The phosphor is completely covering the die base, with 72 independent tiny dies lying underneath it. Very often the phosphor comes off those tiny dies and gives a blue or purple tint to the light, meaning too much UV is escaping.
Try de-doming it only if you’re prepared to replace that $18 emitter.
SFL on my first and only MT-G2 de-dome attempt
Steady hands good view and all. For the record though, I didn’t do a gasoline de-dome, which I’ve had good success with on XP-G2s, XM-L’s and XM-L2’s.
Wow. This is your brain on drugs.
Maybe you gather up the phosphor around the crystals, grind it up, and then glue on top of the crystals. If that doesn't work, you could build a remote phosphor light application.
yeah, I’m aware of the risks of corrupting the emitter. Thanks anyways.
I also think that mt-g2 dedomes will be more common, successful and easy in the future. There is just some learning curve needed. What I was thinking to try is, firstly cut most of the dome top away with a razor and then make multiple cuts to the rest of the dome (probably in between the phosphor lines in order to avoid damage to the phosphor) and then leave it to gasoline (or some other solvent) for some time, try to take off the rest of the dome and mostly see what happens 
Cutting may be a good idea. Using a pick, I try lift off as big a good chunk of the dome as possible. From there, I may get one or two good size pieces and then I'ml basically picking at it from there. It kind of crumbles apart. The area outside the crystals comes off clean. I pick as close to the crystals as I dare and stop there. I would suggest doing the same, using the emitter, and then deciding if you want to do a more aggressive dedome.
I'm guessing DBCstm's emitter may have got too hot, because it looks like there was a lot of melting going on there. Hopefully, he can give a couple more details on what he thinks may have gone wrong. I feel that my guide that I linked above has adequate warning, but he was right to also warn you.
I think gasoline will dissolve your phosphor. Ohaya did a dedome using gasoline and lost most of the phosphor. I don't know about you, but to me the phosphor is a big part of what makes the MT-G2 so great. I think aspherics tend to cool down the beam. So a dedome without losing phosphor could end up being real sweet with this emitter. Ohaya may be able to add details on that.
I usually use gasoline to de-dome, but didn’t on the MT-G2. Instead, I used the Vinh method pretty much like Markow is describing. I cut the dome off with a new XActo blade, very close to the die. It was actually pretty good at that point, but when I went further, well you see what happened.
What is this talk of crystals? There are no crystals. I have the die with zero phosphor, if there’s crystals it’s a microscopic thing that I can’t see with a 10x loupe. I, uh, well, kinda took it down to the trace underneath everything to see what makes it tick. Didn’t see anything that made me think crystal. Probably missing something though, usually do.
So if I hook this back up to power, what will it do? It has nothing on it what-so-ever. Just the trace looking swirling lines that connected all the dots. 
Hey, when you mess up, go all the way right? 
Looking forward to hearing about this, very curious how these things work.
Inspired by you Markow, I decided to play a little bit with a 59mm apsheric lens and a DST with the reflector portion of the head removed. The lens has a pretty short focal length. Before this thread, I wouldn't have considered the MT-G2 and aspherics a good match. I didn't get results like you have here, but I don't have your lens either. I measured lux and it was quite disappointing. I intend to keep trying though. I have a 100mm on the way from FT that I will try next. I could see a light with a big hot spot and no spill being potentially handy.
What I wanted report was that when I fully focused the beam, I could see flaws in my dedoming. The image wasn't hideous, but it wasn't a nice perfect image of the emitter either. I could see variations in the tint across the die and one small spot that was blue. It can't see the spot in a picture I have of the emitter. I will have to try to take a real close macro sometime.
I notice that both DBCstm's emitter and mine have a "black" spot in the same place outside of the field of crystals. I wonder what that is. It looks like there is something under there. It doesn't show in the projected image from the aspheric, but neither does the phosphor area outside of the crystal field.
The beam looked fine, though, when it was just slightly out of focus.
I don't know if this means that complete dedome would look better or worse. I think it's the silicone scraps that I left attached that are causing the variations in tint. It's hard to tell because the die itself has it own variations from the crystals and the gaps between the crystals. The question is, would any phosphor come off trying to get all of the silicone off.
EDIT: I just realized the above is not the emitter in the DST. I'll try to take a picture of that one. I do remember accidentally hitting one of the emitter's crystal field with the pick when dedoming. I also remember that it removed some phosphor at the point of impact. The DST emitter must be that one.
Hey 4Wheelr, that black spot is probably the ESD protection that we see on the other emitters. Being as how it’s a square I’m almost willing to bet that’s what it is here. It’s just buried under phosphor. (As I understand it that means ElectroStaticDischarge protection) might be wrong there, with my memory and all.
Thanks Dale. That makes sense.
I disassembled light that has been subjected to high currents this weekend. The adhesive from the copper tape was hard to clean up. It also looked like the copper and aluminum were undergoing a galvanic reaction. Because of this, I am now going to use plain aluminum foil for most thread wraps. It will be a little less effective than copper transporting the heat across the threads, but seems the lesser of two evils.
Awesome mod! Makes me want to build an aspheric light again, what is the back focal lenght of that aspheric you are using?
Excellent to hear that you got inspired and I noticed from another discussion thread that you got ~400kcd with the 100mm lens and a dedomed MT-G2, WOW :bigsmile:.
I did a MT-G2 dedome (with heating, cutting, and picking) and there is still some silicone on top of the phosphor although its quite flat. Have not tested it properly yet, but the color tint is Ok, so not much removed phosphor I assume. I’ll probably try to do an another dedome attempt with a bare led emitter.
Have you noticed a difference if you firstly use the led with high currents and then try to do a heating dedome or doing it without using it. My thought here is whether the silicone slightly melts on phosphor when used?
What about the gasoline dedoming, I wonder in what sense the MT-G2 is assembled differently as the XM-L2 gasolines seem to be easy and successful as opposite to MT-G2 attemts?
Thanks! I have no idea what is the focal length in this standard Dereelight Xsearcher lens, is there an easy way to measure it?
Yeah, that lens totally surprised me. Thank you for your post to that thread.
I totally respect your courage to venture in to MT-G2 dedoming. You're in a very small club. You have a very good question about the dome possibly being more fused to the phosphor after usage. Seems possible. I've noticed the remaining silicone (after a dedome) seems to harden after usage. I haven't verified that yet. I will try to look into that this weekend when I do some additional mods to a dedomed MT-G2 light I have been using.
I don't know anything about the manufacturing differences between xml(2) and mtg2. They do have quite a few obvious product differences. For example, xml's have exposed bond wires but mtg2's don't. I know you can dedome xml's with acetone. Acetone, in the one case I know of, stripped off the phosphor from an MT-G2. The below picture is from Post 263 of this thread. The emitter in the center was dedomed using an acetone bath.
I get the sense that your dedome did not go the way you wanted, but it also sounds like you haven't used the emitter yet. There are very few documented dedome attempts. After you put your emitter through its paces, I know I, and I'm sure others would appreciate to hear any knowledge you gain (good or bad) from your dedoming work.
EDIT: Edited text because putting an "s" in parenthesis creates a crazy smiley.
Ok, I did a dedome for a bare MT-G2 led emitter only. Here some experiences for this and the previous dedome.
In the first dedome I cutted the top of the dome away as well as did multiple cuts downwards all the way to the led die. Heated and picked the remaining silicone. I think cutting the top of the dome away was good, the multicuts not so good because the silicone needs to be picked in such a small pieces.
With the second dedome I cutted the top of the dome away as previously (my thinking here is that the led die is more evenly heated with a flat silicone), but now only cutted the dome in half. Working with a bare emitter only was also easier and as I applied constant heated air (330C) it was rather easy to pick the silicone off from the edges, the first half came out cleanly the second left some silicone to pick a few times.
What puzzles me is that the surface looks slightly foggy :~ I wonder what causes it? Do you have similar fogginess on top of the die? You can see it clearly if you use the emitter in moonlight mode, kind of glow?
Ok, also did some testing. Selected the best of the two dedomes, so the second one, drove it with 14x7135s (5,2-5,3Amps tailcap). Tint is Ok, warmer, got measures of 110kcd+ with Xsearcher. After testing noticed that there is a small black dot on the led die 
, well… grilled a small area of the die :zipper_mouth_face: :D. It performs similarly though. 
Thank you for the follow up. I will have to check for the fogginess thing. The black spot is most likely flux splatter from soldering the wire to the emitter base. I rinse my mtg2's with alcohol and then use and alcohol drenche Q-tip and gently rub surface of the emitter. Haven't lost any phosphor yet doing that. Unfortunately, it only seems to clean off before being burnt on from being used. Maybe it can be very gentle scrapped off.
I expected a bigger increase in your throw. I will update the throw thread as soon as I can.
EDIT: Throw thread updated.
The cleaning and gently rubbing the surface of the emitter did help. I do get well over 140kcd in peaks with 5,3Amps tailcap, Whoa!, however, this build is not thermally stable (actually this one is a standard p60 pill ), and the intensity drops quickly, after 30 seconds a more descriptive value is 125kcd. With 1,3Amps tailcap I do get a nice stable 42kcd, and as compared to the MT-G2 version with a dome on there is about 100% increase (20kcd with 1,2Amps), which is more than I expected. Just to remind the MT-G2 dome pill was with 12x7135 and this dedomed 14x7135.
Ah, I see. That sounds reasonable. I was expecting your throw to not quite double, but get a good way towards it. 140kcd with the extra 700mA of current sounds pretty good.
Heat sinking that MT-G2 sure poses challenges. Best wishes on finding a solution. Looking forward to your next creation. This one is pretty cool.