A Perfect Dedome?

But shouldnā€™t we be looking for the best silicone remover?

Well, thatā€™s exactly what weā€™re doing :stuck_out_tongue:

And right now my best bet is Toulene.

:slight_smile:

Thing is, toluene is found in what we call ā€˜thinnerā€™ here, so why should we look for ā€˜nitro thinnerā€™ if itā€™s the toluene weā€™re looking for?

I have not checked the tint, but it is a random cool white led from the spares box, the tint is relevant if I would have known the tint that I started withā€¦

Edit: FWIW, I checked tint anyway: pretty good actually, not ugly green, must have been a tint on or under the BBL before the dedome.

OK so the experiment with the solvent I had on hand didnā€™t work. Or should I say it was no better than hot gasoline or using acetone. So I broke down and bought some toluene and will try that and report back. Iā€™ve got 50 of the SST-40ā€™s showing up soon to experiment on. Iā€™m making a TR-J20 for a member here and want to make sure that he gets 12 perfect de-domes in there.

On the bin that turned Rosy, that was quite a while back, I bought them on sale for cheap on one of the big aliexpress shopping days. That was back when XP-G2ā€™s had just come out so for that time they were great but they wouldnā€™t be high bin enough for today, not compared with the S4 2Bā€™s. Still I liked them a lot and wish that more of them would de-dome that color. They actually reminded me a lot of a nichia. The problem with ali-express buys are that you never really know exactly what you are getting. You might get lucky and you might not. So I havenā€™t bought from them in a long time.

Mainly because Nitro thinner apart from toulene also contains several other chemicals that removes silicone. And also because there have been reports of very little green tint shift.

Thanks djozz.

Your 50 x SST-40 order makes my order of 4 feel slightly insignificant. :slight_smile:
Good luck.

The toluene took the dome off very clean. I did slice the dome off pretty close to the bottom before soaking. I didnā€™t boil the emitter on a hotplate. I used the boiling water instead like I would with gasoline. Itā€™s VERY clean. Perfect. Now Iā€™ll build a light with it in a while and report back on the tint. And Iā€™ll compare that tint with the tint from the Hot high octane de-dome.

So far so good, keep your fingers crossed for me.

Thanks Steve. Well the toluene worked perfect and the tint change was minimal. I didnā€™t see any green in it at all.

I use this re-flow block I made for my soldering iron :

I really havenā€™t had time to redo the experiment but maybe one/two minutes in total ?, it was more or less trial and error if it was still green I gave it some more heat :smiley:

Great news thanks, twelve de-domed SST-40ā€™s ? thatā€™s going to be some kind of monster.

Good work! Luckily we have straight toulene to buy here in Sweden, so Iā€™ll probably order some today. The thinner I use now is 80% toulene and 15-20% acetone and the dedomes Iā€™ve done with it turned out too green. Iā€™m suspecting that the acetone is the culprit as Iā€™ve read that it might eat some of the phosphorus when used.

Been on a local supermarket a while ago. They now sell a ā€œturpentine simileā€ whose composition is: C7 and C9-C12 alkanes in n-alkane, isoalkane and cycloalkane forms. Looks good to me, gonna get a bottle tomorrow. Half a litre for ā‚¬1.60.

Well, i hate to say it but Cree has changed the dome`s sillicone againā€¦ā€¦hard times for dedoming are comming folksā€¦XPG2 and XPL are already affected but the change

What are the symptoms of the new silicone on the XPL and XPG2?

Why does a perfect dedome work well?
If I understand DrJones correctly, even a flat dome should reflect less light back towards the phosphor than no dome at all. Reflection of perpendicular beam is down from 18% to 10% (6+4). TIR angle is the same. So total reflection with a shaved dome should be lower, producing better output and smaller tint shift. But numbers here, here, here indicate otherwise.
Can someone explain why is it so?

I have never seen a ā€œperfectā€ shaved dome. So there is more lumen loss with a shaved dome because the top is no longer as smooth and perfect as with the dome on. I imagine there is still some scattering of the light because of the imperfections in the ā€œtopā€ of the emitter. Not that I think a ā€œclose shaveā€ de-dome is bad, because done properly it is still a good way to de-dome.

That was my first thought too. But @relic38 has sanded the shave with 2000 grit paper. I think it should be OKā€¦
Another thought is that in a perfect dedome thereā€™s still a thin layer of silicone left.
Or maybe thereā€™s some more fundamental reason.
Dunnoā€¦

Just killed a LatticeBright ā€œXM-Lā€ by driving it directly from a 3.5+V battery while submerged in white spirit. Gave it a few good zaps a few hours ago, can't say for sure if there was some apparent damage mostly due to my unwillingness to look at the thing while driving it.

Gave it another zap a few minutes ago, and it just died.

I have an old genuine XM-L next in line, but now I am in doubt with regards to submerging it with wires attached.

2013 manufactured cool white XM-L is enjoying a white spirit bath, with attached wires. I've given it some current, but the alu board doesn't even seems to get hot to my finger. Maybe the mia LatticeBright ā€œXM-Lā€ was already ā€œcookedā€, it came from a friend's headlamp whose emitter I swapped.

Going to raise the battery voltage to increase my diver's driving current. :-D

I gave the submersed current method a go a while back, trying to cleanly de-dome some Oslons.

It had promise, but I ran out of emittersā€¦. :slight_smile: