X-ML de-doming method with 100% success?

Ok, ok, I just got some “fresh” gasoline in a small bottle (snuck it in while filling up the car) :)… Will give it a try tonight.


Edit: 21:32 EST - it’s “in the drink” :)!

I unsoldered the emitter PCB from the pill, so it’s just the emitter+emitter PCB in the gasoline.

Had some extra time on my hands so I decided to drop the s3 in a jar of gas. I also have a convoy m2 I might do this to if I like the results.

Acetone is available in quart cans in the paint section of a hardware store. It is a lot less smelly and probably a lot less toxic than gasoline, and you will find other uses for it.

And acetone also stands a good chance of removing the phosphor layer along with the dome. We went through all this in the more recent de-doming thread.


About 2 hours+ now, but not much going on thus far. I know that this takes awhile soaking.

Anyway, I have a question: After the ‘X’ hours, I’ve read that the dome just falls off by itself in the gasoline. Is that right?

I’m also unclear about residue. I’ve seen some posts that say that residue remains, and has to be cleaned off, but others that say that all they did was soak the emitter, and the dome and all residue were gone.

Which is correct?


That says that after taking it out of the gasoline, the “goo” has to be peeled off? Correct?

One way of looking at it is explained in djozz’s “I have been thinking about this.” post here Reflector width vs depth for throw?. The focal length determines the size of the image of the led, and the total light in the throw is mainly determined by how much light reaches the lens. So for a small lens and a long focal length, the brightness of the spot depends only on the lens size and the spot’s size only on the focal length. For a short focal length and a large lens, the brightness depends on both. The dome being convex, it decreases the effective focal length and makes the spot bigger and dimmer.
Another way is that the apparent brightness of a surface is not changed by the optics, except for a slight loss. Looking in the front of a zoomed in SK68, I see solid yellow off or solid bright on, so it is hard to see at first how de-doming it would make it brighter; the whole lens appears to be showing me the brightest surface available. But if I take off the bezel and hold the light close to a surface, I see that the light is brightest in the center. Peaking at the led over the edge of the head where the edge of the lens goes, it appears I am looking at the led’s side, so that is how taking off the dome could help, by looking at it more head on. The phosphor scatters isotropically (I read that in an article.), so (as stated above somewhere) it dims the led at low angles where the path through it is longer, scattering the light to higher angles as well as converting its wavelength.


BTW, here’s one post that seemed to indicate that gasoline removes all the “residue”:


It’s now 01:49 EST, so about 4+ hours and it looks like nothing is happening. Just reporting timeline. Dome looks intact still.

The 'residue' is crumbly bits that come off easy, so easy that if you don't clean it all away there's a good chance it will come off after assembly and bounce around inside the reflector. So easy that you can pull it out from under the bond wires without damage. All it takes is a toothpick, good lighting, and some magnification (and no coffee in the previous ~6 hours). The longer you leave it in the less crumbly bits will be left behind.

Acetone will lift the phosphor layer. Do not use. Gasoline will not affect the phosphor even if left in for weeks. A quick dunk in acetone is enough to mess it up, so I guess you can imagine what several hours would do.

Hi comfy,

I guess that I won’t be able to clean off the residue then :(. The “no coffee in the previous ~6 hours” disqualifies me :)….

Kidding :)!

Its been 16 hours since my C8 & K40 LEDs were marinated in gasoline and when I checked 30 mins ago, the dome of the K40 was already off as well. The C8 LED is already clean and I don’t need to do further ‘peeling’ of residue so I removed it and let it dry. I left the K40 LED in the gasoline marinade because it still has some residue in it. I’ll check it again after 2 hours and by that time, the K40 LED should be clean already and the C8 LED dry and ready for installing to my Convoy C8. :slight_smile:

What I did was shake (a little) the bottle containing the gasoline and the LEDs and the pressure of the gasoline is enough to remove the remaining residue. :slight_smile:

Of course the LEDs were already there for at least 16 hours and their domes have already fallen off. :wink:

I have finished re-installing the dedomed LEDs to my Convoy C8 & my K40 and the results are just awesome!

I have 2 Convoy C8s. All of them are SMO T8 3C and one was dedomed. Here are their beams taken moments ago. I’m using a Nikon Coolpix S710 set at ISO 100 1/60 F6.7:

The dedomed C8 has a warmer temperature and a smaller & more intense hot spot. It also throws like a stock K40.

I added the dedomed K40 to the 2 C8s are here’s their beam shots. I was awed by the dedomed C8 but I was totally blown away by the dedomed K40.

how about soaking in denatured alcohol? or a quick dunk in denatured alcohol after the gas bath?


My XM-L U3 has been soaking for ~14 hours now, and the dome is still intact (not removed)?? I swished the jar around, and the dome still intact :(.

The dome ain’t moving :(!!

Edit: Is it possible that the U3 dome is made of some different material than the older Ux emitters, and gasoline doesn’t work with it?

I left my XPE in for a couple days and had no residual to mess with. Personally, I wouldn’t swish and risk the bond wires . . . .

It’s going on 18 hours now and now movement yet … so just let it sit longer?

Has it swelled up/changed shape? Did you scrape off the flat bits at the corners to give the gas an easier time getting under the dome? You can also make a bunch of small cuts, very shallow, just enough to break the surface, with a razor across the top of the dome to give it a head start.

I have not seen one yet that didn't start showing signs after only the first hour. All variants - XML, XML2, XPG2...