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.
The toluene took the dome off very clean. I did slice the dome off pretty close to the bottom before soaking. I didnāt boil the emitter on a hotplate. I used the boiling water instead like I would with gasoline. Itās VERY clean. Perfect. Now Iāll build a light with it in a while and report back on the tint. And Iāll compare that tint with the tint from the Hot high octane de-dome.
I use this re-flow block I made for my soldering iron :
I really havenāt 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
Great news thanks, twelve de-domed SST-40ās ? thatās going to be some kind of monster.
Good work! Luckily we have straight toulene to buy here in Sweden, so Iāll probably order some today. The thinner I use now is 80% toulene and 15-20% acetone and the dedomes Iāve done with it turned out too green. Iām suspecting that the acetone is the culprit as Iāve read that it might eat some of the phosphorus when used.
Been on a local supermarket a while ago. They now sell a āturpentine 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
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 āperfectā 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 ātopā of the emitter. Not that I think a āclose shaveā de-dome is bad, because done properly it is still a good way to de-dome.
That was my first thought too. But @relic38has sanded the shave with 2000 grit paper. I think it should be OKā¦
Another thought is that in a perfect dedome thereās still a thin layer of silicone left.
Or maybe thereās some more fundamental reason.
Dunnoā¦
Just killed a LatticeBright āXM-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 āXM-Lā was already ācookedā, 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
Test XM-L may be getting ā3A when the multimeter is removed. Remember my testing is being done with my led's bathing fluid at room temperature, this means Vf remains higher also (excellent cooling).
I can see many of you may have killed a good deal of emitters this way because of hot bath (less Vf) plus high starting battery voltage. Seriously.
My old XM-L was left in the white spirit bath, waiting for nature to take its course. I extracted the board a few days ago and the dome nearly fell by itself, leaving just an unimportant tiny leftover where the bond wires are, yet not over the die which isā¦ completely clear! (įµį“„įµ)
I know have an XM-L2 in the bath. The good thing with white spirit is that it does not seem to completely evaporate at room temperature, of course because of the longer chain hydrocarbons.
It is fun to observe the white spirit slowly doing its magic and giving it some stirring just for the sake of it. I can clearly see a curious optical effect in the emitters while immersed: the die looks unscaled, like if it were dedomed. As time slowly goes by it can be observed how the white spirit diffuses under the dome, progressively soaking the die under.
If anyone is interested I believe this slow cooking method may be worth a try with the newer generation Cree emitters.