Figured I'd share my experience since it was great!
Product: Deacon Industries 770-L high temp sealant
Background: eventually I want to print peek, ultem, and maybe eventually get crazy and try polyimide and other imides. Yes, all high temp. Ultra RTV only goes up to something like 250C. I can't remember exactly, but iirc it wasn't even over 9000, err 300. Not even good for some polycarbonate printing. When I first got my e3d I didn't need sealant. They cut their threads pretty tightly it seems...or I got lucky. After some stupidity on my part, and more stupidity in the form of a jam I found I had some plastic in the threads of the heater block (and the nozzle). No problem, grab the tap and die! Bad idea. Perhaps these were garbage taps/dies (shouldn't be) or more likely just a looser tolerance since I found some metal shavings afterwards. I finished reassembly and found I had plastic all over the heater block. Obviously I ordered a replacement, but figured I'd try sealing it anyhow. Teflon tape for now since I'm only printing pla. It worked. I'm considering making my own heater block, but I'm not going to spend the time chucking it in a 4 jaw, centering on that hole, and cutting tight tolerance threads, so I had been looking into sealants anyhow. I contacted the sales info at deacon to make sure the sealant wouldn't react with the metals in the hot end in any way. Their sales material covers reassembly (no it won't interfere). So I gave it a shot.
Overall: it stunk a bit when setting. Beyond that, it sealed nicely. Overzealous application led to a temporary jam I was able to flush out with plastic (had some black bits coming out for a while that wasn't burnt plastic! Beyond that, application was simple, and my hot end is tightly sealed. The 770L formula is good 510 degrees c with some users reporting much higher temps without issue.
Warnings: it does contain "hazardous" particles. These are suspended in the resin, unlikely to escape even in disassembly. It's pretty much a non issue, but the warning has to be there thanks to the new idiotic ghs. It does smell bad. Generally things smell bad to us because they are bad for us. Nothing else is listed in the sds, however, so it "should" be "safe". Regardless, next time I use it, I will do so outdoors and I'll cure it with a heat gun rather than just printing! I also made sure to clean up all sealant that remained externally while it was still a liquid just in case as it cured some particles without two walls decided to escape the resin. Unlikely, but can't be too careful. May even wear a mask. I didn't but to each his/her own. Just don't say some guy on the Internet told you it's totally safe and there's nothing to worry about. It has warnings, precautions/instructions to follow, and basically says if you do as they say, you won't be exposed to anything in a level determined safe from a legal standpoint by government agencies. Of course part of those instructions were to use the product only in an industrial setting, so Ymmv!
Cost: it's up there, especially compared to RTV. They also recommend keeping it refrigerated to improve shelf life. You have to buy a fair amount of it. I used probably 3 "drops" of it which was too much. If it would keep forever, the one can would last me a lifetime or 3. I had drop in quotes because the stuff is highly viscous. I used a bamboo barbecue skewer to apply it. It's a few times thicker than honey, so you can understand why drops was in quotes!
Disassembly: I should probably test that part out. Worst case is I run taps and dies back over it, but it should come off with just a little force. Next time I jam the printer I'll update
I figure I can't be the only one looking to print high temp polymers! As such I can't be the only one tackling sealing...but then, maybe I wasn't just lucky, and e3d really does make tight tolerance threads combined with thermal expansion rates of the metals used so it doesn't need sealant. Regardless, if you find yourself in need, thanks to a tap and die, too many reassemblys, just unlucky/normal with leaky threads, or any other reason like making your own hot end, or working with a lower quality, different materials which don't seal (I'd like to eliminate the aluminum heater block since at 400C it's got a tensile strength of an amazingly high 1500 psi....yeah, it gets *THAT* weak, and continues getting weaker as temps go higher. Granted it's not under a lot of stress either, but that's a whole other discussion for another time/place! Just offering another reason you might want this
), it's out there, easy to use, and works.
I specifically didn't include purchasing links. I found it with Google pretty easily, but I don't want this to seem like advertising, or recommend a specific vendor, just a product.
Edited to correct the temp range of the product! I was close
Edited 1 time(s). Last edit at 07/26/2015 01:42PM by corry.