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High temp sealant review

Posted by corry 
High temp sealant review
July 26, 2015 01:15AM
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 smiling smiley

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 smiling smiley ), 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 smiling smiley

Edited 1 time(s). Last edit at 07/26/2015 01:42PM by corry.
Re: High temp sealant review
July 26, 2015 07:29AM
Thanks for the info. Perhaps it's time we started using pipe threads for the nozzle smiling smiley
Re: High temp sealant review
July 26, 2015 01:10PM
Not sure if anyone finds it helful but for high temp seals there is a forgotten alternative, at least for screw connections.
Since I was a teenager (please don't ask how long ago that was!) I tried to use old school remedies if there is no better modern alternative.
One part of this collection is sodium silicate or "waterglass".
You can make it at home with drain cleaner and silica gel if there is no source available.
In the liquid state it is should be almost as thick as honey and for thread seals you apply it with a brush or by simply dipping the thread into it (not recommended for hotends!) , does not matter too much if there is too much on the part.
Once it gets over about 280°C all the water left in it will boil away and the sodium silicate forms a crystal structure - perlite.
Because it expands while doing so a thread will be sealed properly and unless you go over about 950° celsius there will be no problem, if you use enough eat for the curing (more than 1000°C) the resulting seal will last up to 1200°C - in case you want to use ceramic hotends and print metals directly. Please don't ask about suitable extruders and feeding mechanisms or how to make a 0.5mm ceramic nozzle winking smiley
Re: High temp sealant review
July 26, 2015 01:21PM
Thanks! I'll have to look into that. Is it really pearlite? I've got to research this....Perlite is useful for a lot of other things as well!

How about disassembly? Does it come off the threads easily once cured?

I'm not happy with the shelf life of the 770-L, but $50 or so a year for getting nice, easy to use high temp sealant, isn't a bank account killer, so its definitely usable, and I know it works. Always up for an alternative though!

Also, thanks for posting it here. I found a severe lack of information about it. Maybe I just had the wrong search terms....none of us are truly unique though, so if I couldn't find it, there are others using the same search terms and ending with the same frustration! Hopefully this helps those people smiling smiley

Edit: Hmmm, cant find any mention of it becoming perlite....it is used to bind it as well as vermiculite, but everything says when heated it becomes "glass like". Still may be very useful for thread sealing. I saw its used with car exhaust repairs, so it definitely stands up to the temps...

Edited 1 time(s). Last edit at 07/26/2015 01:29PM by corry.
Re: High temp sealant review
July 26, 2015 07:29PM
Most really high pressure seals are metal on metal. The nozzles really need to be designed wit a tapered metal to metal seat to prevent leaks.
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