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PETG Finishing / Polishing - Any Solvents?

Posted by TyCobb 
PETG Finishing / Polishing - Any Solvents?
November 24, 2015 10:34AM
I just started printing with PETG because I am pretty sure the ABS odor was causing the dog to get sick.

I am loving the PETG so far, but I cannot find any good information on finishing and polishing it. It appears as though it is immune to acetone. Flame polishing would probably work, but I have no experience in that. I'd like to be able to paint it on or try vapor smoothing if possible.

Has anyone had any luck finishing with PETG? Would love to hear some experiences. Thanks.

If this is the wrong board, please let me know and I will re-ask in the appropriate spot.
Re: PETG Finishing / Polishing - Any Solvents?
November 25, 2015 08:52AM
Bought Tuff Strip since it contained toluene which I heard may work. Unfortunately you cannot find just toluene in California. Tuff Strip was nothing, but an workable gel.

Tried acetone just for the hell of it and yep... it did absolutely nothing.

Bought a hand torch to test flame polishing. May work okay, but using white filament makes it really hard to see a difference until it is too late. Not to mention the fact that it can easily discolor and start looking like a toasted marshmallow. Hmm maybe I should print out a marshmallow and throw the torch at it.
Re: PETG Finishing / Polishing - Any Solvents?
November 25, 2015 09:03AM
... gentle sand-blasting (or glass-microspheres) maybe?

Re: PETG Finishing / Polishing - Any Solvents?
November 25, 2015 09:22AM
Heh, sand blasting was actually recommended by a coworker. Seemed like overkill, but maybe I'll try to find a small blaster if I really need it.
Re: PETG Finishing / Polishing - Any Solvents?
December 31, 2015 04:48PM
I've heard PETG can be solvent welded with a mixture of methyl ethyl ketone and cyclohexanone. Next time I print some I am planning to try neat MEK. I also ordered some cyclohexanone to test, but it hasn't gotten in yet. Either way, it can presumably be polished with the same solvents that solvent weld it, under appropriate conditions.

Cyclohexanone was $0.30/mL in the lowest quantity I could find, declining rapidly if you're willing to buy a couple liters. (And have the facilities to safely store it, which I do, but I didn't want to take a big risk buying liters and liters of it only for it to not work and end up taking up space in my small flammables cabinet forever.) $0.30/mL is probably cheap enough for solvent welding but might get expensive for some forms of vapor polishing.

The risks of cyclohexanone are essentially comparable to acetone. MEK is slightly less benign but is also broadly similar. MEK used to be readily available, but the jackbooted crowd decided it was a "precursor" to illegal drugs (you know, like how people could use air and water to grow opium poppies!), which may be responsible for its declining availability to consumers; unfortunately it's too flammable to make hoarding it a good idea. Hopefully cyclohexanone works alone.

Edited 1 time(s). Last edit at 12/31/2015 04:51PM by Bryce.
Re: PETG Finishing / Polishing - Any Solvents?
February 02, 2016 07:32AM
Sorry for the delay in updating:
Cyclohexanone can be used alone to solvent weld PETG. I welded two plates about 30mm by 50mm together with about 100 uL of cyclohexanone. I wiped one plate across the other and then pressed them together firmly. They held within less than a minute, similar in all respects to acetone on ABS.

Acetone and MEK alone also appear to be usable, quickly holding. I haven't done formal tests yet (kinda in a rush to print some things for work) but after 12 hours or so the cyclohexanone was not breakable by hand whereas the MEK seemed to have not hardened nearly as well and broke apart. I haven't tested how the acetone holds up yet.
Re: PETG Finishing / Polishing - Any Solvents?
June 01, 2016 06:26AM
methoxypropanolol works well as a solvent (used in a lot of AV marker pens) and solvent adhesive.....

heat treatment and polishing works well using a hot air rework desoldering station... it blows hot air at a predetermined temperature... heat setting is trial and error but I found 260c worked well for me....... it needs to be hot enough to "glaze" quickly whilst not hot enough to soften and distort

hot air rework solder stations are available at reasonable prices from many dealers (prices vary wildly)

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