Vapour polishing anyone?

Someone mentioned this to me on an off hand comment.

Basically using methylene chloride in a metal container with a glass roof which is then gently heated until it turns to a vapour. The vapour “melts” the top surface smoothing it out giving a great finish. I know it works with only certain types of plastics and was wondering if anyone had played with it with the form labs resin before I go and buy some?

FYI methylene chloride is VERY nasty stuff so make sure you take appropriate precautions with it!

I’m basically looking to find a good way to finish parts with a lot of little details that mechanical sanding would just be impossible on.

Gary is right: it is wicked stuff:

“… toxic to … the nervous system…”

More here: MSDS

Yikes, I’ll stick to sanding.

Thought that might be the case guys. I’m still going to have a bash using a failed print piece to experiment with (even failures have their uses!).

I’ll report back with what I find.

I do this quite a lot with FFF printed ABS & acetone.

I will give it ago later this week and let you know how I get on.

Thanks Steve. I’ll wait until you have had a play before buying the more dangerous chemicals along with the safety gear

Hi Gary,

As a preliminary test, I popped some Grey & Clear failed prints into a jar of acetone and left it over night.

What I was hoping to see this morning was the parts dissolved into gooey, sticky mess. Unfortunately this wasn’t the case.

The acetone had affected the parts in that they became very brittle, almost crumbly.

So in conclusion I don’t see an acetone vapor bath have the desired smoothing effect.


Thanks for carrying out the test. I suspect that if acetone didn’t cause the polishing effect then something more aggressive also wouldn’t unless there’s a chemist in the building that could say otherwise?

Other techniques that jump to mind would be flame polishing or even just a very gentle oven bake but these obviously have their own issues when it comes to the dimensional stability of the model.

Here’s a pic of the kind of thing I’m looking to print off and polish up and as you can see, polishing in amongst all the details would be a right pain manually!


It’s my belief the material is a “cross-linked acrylic”. Maybe hit Google up with that info.

A much safer way is get an Air Eraser from Paasche:

I have had the little one for a couple of decades now and it works really well really quickly to take off build lines without destroying details. It will leave a mat finish behind.

Personally I would be weary about using any kind of solvent on plastic, you don’t know what it does to the material over time. Cooking chemicals in your house doesn’t sound like a very good idea.

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I wonder if you could use a vibration polisher w/ a non-agressive media?

That would depend on the type of part, some may be too fragile.
Air eraser works really well, if you have a big plastic container you can spray towards that to gather the media and re-use it. The media doesn’t float around but you should wear some sort of mask so you don’t breath any in.

I have had good luck with it so far.

Ah, I see… it is a little sandblaster.

Yup, and I’m sure it is a lot easier to control than globally melting an object in a toxic fume bath.

Reminds me of that show Breaking Bad…

Since this is a UV cured resin, it will be tough to find something safe that will smooth it like acetone does with ABS. For the example part in the pic an easy way to make it shiny would be to dip it in resin or paint it on and then cure it in sunlight or a UV oven. It gives a smooth shiny surface as seen if you have ever repaired a part with resin or simply had a drop of it cure on something.

If the part is real “ridgey”, you could sandblast first and then coat it.

Best bet is to sand or use an air eraser to clean up and smooth the surface then for a shiny polished surface spray a light coat of varnish. Many shops that print from polyjet printers use an acrylic varnish to give it that gloss look.

Other refs :

For larger jobs
Thanks for the pointer