A Perfect Dedome?

I’m almost sure that Toulene is the ingredient that does the trick. I have a thinner with over 80% toulene, 15% acetone and a few percentage of methyl and isobutylene. It dedomed an xm-l2 in under two minutes. Completely clean.

The tint was however not so great. That’s why I’m still looking to get Nitro thinner.

Wow that’s fast. Too bad it changed the tint, hope you find the Nitro thinner.

I’m not worried about it for the XM-L2’s or XP-G2’s but I’d really like to find something that works wonders on the new SST-40’s. I love their output and the fact that they can be really over-driven in a big way. They seem to clean up good when I first cut the dome off and then use the Hot Gasoline trick but I’d like to see them be absolutely perfect if possible.

What was it you didn’t like about the tint change with toulene? I have only done a few , but my first few I tried with gasoline, turned green. Hot gas made a difference, in that they turned more yellow. I’m kind of color blind, so I don’t know if that makes a difference to most, but it seems more natural to me. I just use a shotglass (that I’ll only serve shots to someone else :rage: ), with gas, and set it in a pot, pouring in boiling water. The gas usually starts boiling within a minute. Xm-L2’s come completely clean within a few minutes. Xp-G’s, I might have to add more hot water, to get them clean. I am hoping for the minimum Tint change, but understand it’s going to happen. Thanks

The tint turned very green. I did it exactly the same way you did except with thinner.

Are you guys sure that the solvent made your leds turn green and not the tint of the led you started with? To me it is a bit of a BLF-myth that the used chemical for dedoming has any effect on the resulting tint.

Yes, it went extremely fast. My best bet in acquiring Nitro in Italian eBay. Sure, it might be a bit expensive, but if it works it will be worth it in the end.

I’m thinking of buying some of the SST-40s also. If I do, I’ll definitely try dedoming them with thinner and report back if it’s a success or not.

As I’m still very green at dedoming, I really don’t know what the actual cause is. The ones I’ve tried it on are XM-L2 U2 1a. But I’m not really sure if they had a hint of green in them in the first place.

Thank you djozz for saying that. You are right. I don’t know the exact bin of my first few. Knowing, what I have done since, I am much happier with the outcome. Still, even though I’m color challenged, I see a pretty big difference between a domed, and de-domed led. Everyone says they get warmer. I don’t know what that means. All I see is blue, green, yellow, orange , and red :slight_smile: .

That’s what I’m thinking. Dunno anything that’d eat certain “types”(??) of phosphor, eg, those that emit red and yellow (leaving green), yet leave alone other “types”.

Unless different phosphors are put down in layers vs as a mix, and a sloppy dedome takes off a bit of the topmost layer. But you’d see that on the blob of silicone that comes off, I’d imagine.

Don’t think phosphor would oxidise, form a hydrate, etc. Especially if nobody notices any green-shift of a long-dedomed LED that’s been in a flashlight for years.

Ha!

Some of the LED’s I have de-domed had a bit of green on the very low modes. I have been experimenting with heating up the LED after the de-doming this actually seems to reduce the green significantly. I don’t have any specific method yet it’s more trial and error at the moment. I heat the LED on the MCPCB as you would with a re-flow, I find this eliminates most of the green on the low modes, so far I have done four (two XM-L2 & two SST-40) and they turned out great. I still need to do some more LED’s to see if I can replicate the results or if I just got lucky.

Most of the LED’s I have de-domed until now was of unknown tint but the difference between a C or a D tint must have a impact on the de-domed tint. One of the best tints so far was a XM-L2 3D came out really nice if you like the warmer tints.

EDIT :

I have ordered some XM-L2 U3 0D and 0C to see what difference if any the tint makes.

Here are some measurements on the tint shift from dedoming: de-doming: illustrations for color changes and increased luminance

I think the majority of the tint shift is a result of the dedoming itself rather than the method. See here for some discussion: Flashlight Optics - Dome, Dedoming and Throw

I’ve read through this before and I’m bound to agree with it. But then I read that Mitko and another member here mix chemicals so that no tint shift occurs. Then again it’s impossible to know if it’s true or not when they are reluctant to share their method…

In all fairness, mitko did share his meathod here,

Ah, I forgot about that post. But he never revealed how much he used of each chemical.

It seems that people with the best results are using a mixture of chemicals. I’ve wondered, are the domes pure silicone? Also, I’ve wondered if there might be some kind of glue or other substance to help the silicone adhere to the substrate. I would think silicone would adhere on its own but after dedoming a number of times the silicone seems different where it meets the substrate. I believe that it is just silicone but i through these thoughts out there in case I’m wrong.

How much did you heat the mcpcb? Just enough to melt the solder under the LED or longer than that? And did you use a hot plate or iron?

I got these bottles, hit them with a hammer, and they all break.

This new batch of bottles, I rinse with bleach before hitting them, and most of them stay intact.

That’s kinda the problem, that there’s no redoing the dedome with the same LED. Someone gets an “old” batch of XP-Gs, then a “new” batch of XP-Gs, and claims or actually sees a difference with a different solvent, but there’s no way to know that the LEDs all had the same exact tint (they’re tint bins, don’t forget) beforehand, and then acted differently after dedoming.

Or as I asked afterward, wotnahell are those chemicals. Spelling counts in chemistry, else things go boom.

I did a new XM-L2 dedome with my ‘nitro-verdünner’, but now left it overnight without heating up (it is summer here so +20 degC even at night). The dome was next to the led the next morning. After drying I just blew the last bits off.