A Perfect Dedome?

Thats because the light is more concentrated now. See laserpointers..

I wonder what chemical in gasoline is doing most of the work. They do sell Xylene in the hardware store. If it doesn't work, then dump it in your gas tank for a slight octane boost.

Can you spray it into a cup and then apply with small brush, or a dropper? How easy does it flow out before it's cured?

Haven’t we been saying to use gasoline for months now? Where have you guys been?

+10, Excellent!

Honestly, I've never tried. The spray emitted from the can is pretty thin, as is a single coating from same. When used as an electrical insulator, I make two or three passes.

A year's worth of use has left me with just under half a can left, FWIW.

Even with the Internet it takes time for word to get around. I’m here daily and only recently heard about it. I don’t read every single thread every day.

I'm sure you're right, but it's been difficult to find for sure what the best method really is in all these postings and threads with the mix of successes and failures. Think we need a shared googles doc just for dedoming, or some way of summarizing the experiences. The big thread on dedoming is just way too big to get a bottom line answer from. I'm still not sure exactly what to do with the gasoline method. If you could reference threads/posts with specifics, that would be a great help. My questions with gas:

  • does the octane, content, source of the gas make a difference?
  • 12 hrs min time, but ok if longer?
  • Is all the silicon remnants supposed to be completely gone off the LED? I found it wasn't and needed to be pushed off - maybe I did something wrong?
  • can you do just minimum amount to cover the LED dome for the soaking, or should you use a full jar/can of gas? Does it matter?
  • the LED Seal stuff sounds good. Is everyone using it? Any side effect like measured output drops?
  • should the wires be clear of the gooey stuff as well or only the surface matters?
  • should the LED be rinsed/cleaned after the gas soaking? How? I used isopropyl alcohol - seemed ok, anything better?

When I used acetone, I thought the rule was 30 minutes, then that's it, good to do. But it didn't work out that simply. There are several ways of doing the heat method, but again, seems like details are lacking, or skills/knowledge of what to look for are not there. I think what happens is if you have success with a method, you stay with it, so if someone has 100% success rate on a heat method, why change? But for someone trying this for the first time, it seems like the gas method is the best way to go perhaps.

Also with the chemical approach, I think everyone is a little apprehensive about potential damage and long term effects, follow-up care/treatment, etc.

I think there’s some confusion about what octane rating means.

iow, 92 octane from one supplier might be a different cocktail of hydrocarbons than from another…but they should ignite at very nearly the same conditions

For the record, I did mine in 87 octane, and it was fine. I’m confident the octane is not what’s eating the dome.

I just tried using silicone conformal coating on the de-domed emitter and the results are troubling.
Dedomed XM-L @ 700mA (more details in my earlier post)
Before coating: 264 lm
After coating: 252 lm
It’s not huge, about 5% loss. Worth noting anyway. Since the LedSeal is silicone based, I’m thinking it would have a similar effect. Maybe spraying a very light coat is the best way to do it.
Is the coating even necessary? What happens if you leave it?

I'd give up ~5% to know those teeeeny little gold wires were protected.

I dunked it in gasoline again for a few minutes and it recovered some of the loss; back to 257 lm.
I agree that having some protection is good. I was more concerned about the phosphor layer browning, but I read somewhere that it’s coated already.
The bond wires are made of gold, so they will not degrade in open air. Physical contact with them is not good, and LedSeal isn’t going to help with that.

I’ve handled de-domed xml2 pretty roughly. No problems.

The bond wires are delicate, but after the dome is gone, they tend to get squished down instead of yanked off (from handling….a tool slip is a different story)

The phosphor on the xml2s is pretty tough.

I’ve done a similar experiment to relic’s but with clear acrylic spray instead of led seal, and I was measuring throw not output.

I got about the same decrease (~6%) w/ one light coat.

Even so, the hydrocarbons used are likely to be very similar. By trying different octanes, it gives a clue as to which chemical is doing the job. That's why I mentioned Xylene earlier. That's a component of gasoline with a higher octane rating. If folks find that higher octane gas is more effective at dedoming, then the next step is trying Xylene or other high octane components of gasoline. Toluene is also worth checking out.

Folks should be careful around gasoline and its components, not just because of the fire risk, but also because components of gasoline are made up of aromatic hydrocarbons that have strong links to cancer. I'd avoid direct contact with skin and would have good ventilation.

Interesting, good input. I was so careful in handling the dedomed LED. I know I accidentally hit the domes all the time with a finger, knuckle, etc., and usually go over it with alcohol before buttoning it up. It just looked so vunerable, naked and all - now don't get too excited .

FWIW.

I dedomed an XML at this time last year and put it in a light that gives it around 5A.

I've not used anything to coat it and there is hardly any "goo" left anywhere.

It probably has around 100 running hours on high since then and it put exactly the same amount of light out today as it did the day I dedomed it.

To put that into perspective I think of it this way. By the time it burns out I'll have at least xml2 or 3 or even 4 to chose from to replace it.

So I think that as long as you do not mechanically damage the wires or phosfor you and your led will be fine.

Is there an alternate to petrol (gasolene), I cant keep it here as the wife has a problem with it similar to the problem I have with alcoholic beverages.

Thanks ChicagoX.

Going along the lines that somethings that works in one place and not another, we have flyspray here that says on the instructions on the can that it will kill spiders in the state where I live but apparently will not kill spiders in the state next to us. I have noticed lately that there is a lot less spiders here. I'd say that they are all moving to the next state (NSW).


What about its components like toluene and xylene? You should be able to find those at your hardware store. Whatever you don't use for LEDs you can put into the gasoline tank of your vehicle.

-I'm pretty sure that its irrelevant. I just included the octane rating as a fun fact. :D

-I left an XPG in gasoline for three days, didnt harm it.

-It should be off the phosphor because it will block/diffuse the light. If its not completely gone, give it more time.

-I used a 0.2cl glass for schnaps, about half full. So I say the amount does not matter. But you have to cover it (foil for example) because otherwise it will be gone after half a day.

-never used LED Seal and neither did anyone else in Germany. SST90 has air between dome and phosphor.. I think putting anything onto the phosphor would have negative effects on the throw because you'd increase surface area again.

-surface matters.

-I didnt clean it because gas is fugitive.

The tips about being careful with gas.. seriously? Of course, dont drink it, but you will be in closer contact to gas when you use a chainsaw, lawn mower or just fill your car.