A Perfect Dedome?

Thatā€™s the kind of stuff that pisses me off about some of the folks in this forumā€¦ā€œsecret methodsā€. Thank you for sharing your method, it was very nice of you. To me this forum is about helping others that are in the same hobby as you are. Itā€™s not aboutā€¦haha,Iā€™ve got a better way and Iā€™m not telling youā€¦crap like that belongs on the ā€œother forumā€ā€¦not on BLF.

:+1:

Iā€™d like to say thanks to everyone who shares their tips in this thread. Iā€™m a hot high octane person. I use very hot high octane gasoline. I started doing this myself after I found out that trying to de-dome in gas during the winter wasnā€™t working that well. Old Lumens was having great success in his sweltering workshop and I always had good success when I first started because it was summer time. When winter hit it wasnā€™t working as good so I started heating up my gasoline. I put my emitters in a small porceline crock that I fill about a quarter full (little less than that) and float on top of a large bucket of super hot water.

The Hot high octane does work with the SST-40ā€™s but itā€™s not as clean as the one with the mystery solvent. I say ā€œmysteryā€ because itā€™s hard to know exactly what itā€™s made of. Here in the US our solvents have become more ā€œgreenā€ (for lack of a better word). Everything we use is now more environmentally and medically safe.

I used to restore Victorian houses for a while and painted a ton of them using oil paint. Of course we used a paint thinner and Yes I also washed my hands and equipment with it. But at the same time my wife who ā€œdoes nailsā€ was also using similar products to remove nail polish. As the green movement hit our solvents became weaker and weaker and less effective as well. (Same thing goes for the freon and other products used in refrigeration).

On the ā€œmysteryā€ product; My first thought was that the ā€œnitroā€ part of the name had to come from ā€œnitrocelluloseā€. Nitrocellusose is a type of finish, itā€™s a ā€œlacquerā€. Iā€™ve used it to finish guitar bodies and I have seen it used on cars. In the US we also have Lacquer Thinner. But not all lacquer is the same, far from it. So come companies make a lacquer thinner that matches their own brand of lacquer. Cars use a different lacquer than guitars. So which solvent to try? Again this is very hard to say it might not be any of them ā€œexactlyā€. Thatā€™s why it would be nice to know exactly what the ingredients are in the ā€œmysteryā€ solvent. Itā€™s also likely that itā€™s a combination of chemicals just like our other various solvents on the market are. But in the US one of the missing ingredients from going ā€œgreenā€ is often Toluene. Yes they actually used Toluene as an ingredient in nail polish remover and paint thinners. Also most cars are no longer finished with any type of nitrocellulose product.

Iā€™m guessing that even the solvents used at body shops are not going to be the same as they once were. However, as some people are still painting and finishing cars the old fashioned way, someone in that industry probably has access to the old style Nitrocellulose thinner. Same can be said for guitar luthiers. (I do french polishes on my guitars but not with nitrocellulose). StewMac is one of the luthier shops that I use and they have two different types of Nitrocellulose thinner. One is their own brand and one is brand specific. These might be worth a try. I have also seen a type of nitrocellulose thinner that is used by some of the guys who paint and finish cars. That might be even closer to the mystery solvent. Itā€™s also possible that none of these are the exact solvent because it might simply be that the mystery solvent is one of our Pre-ā€œGreenā€ paint thinners. These new solvents might be missing a number of chemicals actually.

Iā€™ll try out a few of these solvents and see if I can find one that works as well as the mystery solvent. Hopefully Iā€™ll find something that I can share in this thread to help add something of value. Mostly though I will be trying to find something to work better on the harder domes that are more difficult. The Hot High Octane method works great on the XMLā€™s and XPG domes already.

Thanks again to everyone who is helping out on this thread.

I might give this one a try first.

http://www.rustoleum.com/product-catalog/consumer-brands/auto/paint-chemicals/professional-grade-lacquer-thinner

http://www.rustoleum.com/MSDS/ENGLISH/248671.pdf

You can see from the MSDS that it includes Toluene, Acetone, Ethyl Acetate and Methanol.

Fooey. Neither EtOAc nor MeOH does anything to silicone. Personally, Iā€™d stick with straight toluene. Probably cheaper per gallon, too.

Unless someone wants to mix up a witchā€™s brew of xylene, toluene, MEK, and other HC nasties. Might be mutual ā€œadjuvantsā€ to softening silicone.

I think toluene could be a option as well, if I can find something smaller than a 5 L (1.3 US Gallons) canister :slight_smile:

I thought about toluene as well, but I couldnā€™t really tell from your comment on it if you were saying that the ā€œmysteryā€ stuff was mostly Toluene or if you were referring to the stuff Jdozz used that didnā€™t work so well.

Pretty much all of the solvents have a different ā€œspecialā€ add mixture of various chemicals. If it is Toluene that works correctly then that would be very cool. Maybe you could try it and report back to us? That would be cool too. Right now Iā€™m trying a stripper that has toluene in it that I had laying around from a project. It also has acetone (which will remove domes but not that great), methylene chloride and methanol.

Iā€™ll report back in a while and say how it goes.

Same here. I was surprised they had any in stock at all, but they did have a gallon of Toluene at the hardware store in town, something like $26 though. (Which Iā€™d pay if it actually worked really well). Iā€™m sure it would be cheaper at a large hardware store, but for me thatā€™s an hours drive away.

Iā€™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. Thatā€™s why Iā€™m still looking to get Nitro thinner.

Wow thatā€™s fast. Too bad it changed the tint, hope you find the Nitro thinner.

Iā€™m not worried about it for the XM-L2ā€™s or XP-G2ā€™s but Iā€™d really like to find something that works wonders on the new SST-40ā€™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 Iā€™d like to see them be absolutely perfect if possible.

What was it you didnā€™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. Iā€™m kind of color blind, so I donā€™t know if that makes a difference to most, but it seems more natural to me. I just use a shotglass (that Iā€™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-L2ā€™s come completely clean within a few minutes. Xp-Gā€™s, I might have to add more hot water, to get them clean. I am hoping for the minimum Tint change, but understand itā€™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.

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

As Iā€™m still very green at dedoming, I really donā€™t know what the actual cause is. The ones Iā€™ve tried it on are XM-L2 U2 1a. But Iā€™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 donā€™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 Iā€™m color challenged, I see a pretty big difference between a domed, and de-domed led. Everyone says they get warmer. I donā€™t know what that means. All I see is blue, green, yellow, orange , and red :slight_smile: .

Thatā€™s what Iā€™m thinking. Dunno anything thatā€™d eat certain ā€œtypesā€(??) of phosphor, eg, those that emit red and yellow (leaving green), yet leave alone other ā€œtypesā€.

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 youā€™d see that on the blob of silicone that comes off, Iā€™d imagine.

Donā€™t think phosphor would oxidise, form a hydrate, etc. Especially if nobody notices any green-shift of a long-dedomed LED thatā€™s been in a flashlight for years.

Ha!

Some of the LEDā€™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 donā€™t have any specific method yet itā€™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 LEDā€™s to see if I can replicate the results or if I just got lucky.

Most of the LEDā€™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