Have you guys seen this? It seems a lot safer than using acetone vapor bath.
http://www.youtube.com/watch?v=VvCEnA0NEG4
Wish there was a way to do this with PLA!
@Patrick_Ryan
Use Tetrahydrofuran for PLA.
Same procedure as with acetone.
@Sven_Eric_Nielsen When I hear “tetrahydro…” I can’t help but think that’s not very nice stuff… 
@Patrick_Ryan that’s how thc starts lol
@Patrick_Ryan Is right to have qualms. Compared to Acetone it’s a bit unstable: Wikipedia says " One danger posed by THF follows from its tendency to form highly-explosive peroxides on storage in air. To minimize this problem, commercial samples of THF are often inhibited with BHT. THF should not be distilled to dryness, because the explosive peroxides concentrate in the residue." so, if you accidentally let it boil dry during your vapour smoothing you get a nice unstable explosive peroxide. Personally, I wouldn’t touch the stuff unless I owned a lab.
Lol, and acetone is OK for u?
don’t understand…
@Sven_Eric_Nielsen Well yes, Acetone has no proven adverse health effects beyond being an irritant at very high concentrations and although it is flammable, it takes a direct flame to get it going. It sure as shit doesn’t explode in the same way an unstable peroxide will.
@Tim_Rastall l acetone vapor, on the other hand, will explode. So there’s that.
I don’t think peroxides actually explode. It’s an oxidizer so it oxidized a fuel, generally something around it, be it the paper towels, the metal can, the pla. Oxidizers are very difficult to extinguish though. This is I’d I remember my chemistry correctly. Either way, still dangerous
If anyone tries this, put the can in a bucket to prevent the acetone from flowing across the table once it leaves the can. Acetone is heavier than air.
On PLA smoothing, what about NaOH? I also read a mixture of methanol and lye does have similar effects as diluted acetone does to ABS. And the BetaSolution, of course: Propan-2-ol, potassium hydroxide and aluminium hydroxide.
For PLA you can only use THF on one particular resin from natureworks, on most filaments it doesn’t work. Dichloromethane or methylene chloride (same thing) works as a solvent for all types of PLA that I’ve tried. Some don’t polish up as well as others, but in many cases it works quite nicely.
NaOH etc breaks down PLA as far as I know - useful for dissolving PLA support material but not for polishing objects.
You’re gonna want to use a vent hood and ppe if using thf.
@Ashley_Webster I have run ABS parts thru a tumbler. Tumbler was a large commercial unit with ceramic elements and water bath. Owner usually tumbled billet parts for 30mins. After 30min with my parts, no noticeable difference from the start. after 4 hours it just applied a uniform finish. Tumbler with ceramic elements did not break down and smooth the surface at all.
@Eric_Moy Yeah, quite correct. Given that pla is a sugar derivative, and seeing how it burns. I’m sure that it would provide an ample fuel source for a peroxide reaction. Incidentally, the thf linked to above looks like it doesn’t have a bht inhibitor and it says on the bottle “laboratory grade”.
@Tim_Rastall , would be quite an interesting experiment though…
@Chris_Lau I don’t think a bucket would be necessary. What I understand from this video is that you pour just enough acetone to moisten the paper towels inside the can. There should be no acetone leftover. Which probably explains why this process takes a lot more time than boiling acetone. I was very weary of attempting the boiling thing, but this seems innocuous enough.
I think what @Chris_Lau is referring to is the acetone vapor. The can is going to have the vapor floating around due to the large surface area of paper towel and the volatility of acetone. He’s saying to capture the vapor, get a larger bucket, otherwise the vapor escapes and will condense on your table, possibly damaging it.