Hi guys,

I need a bit of help.

As part of a non-puzzle related project, I needed to stabalize a pipe within another pipe. There was about a .5mm gap, so I just coated one of the pipes in smoothcast 300 and slid it into the other pipe and let it dry. It worked great.

But now I need to REMOVE the pipe. And it is stuck royally. Neither of the metal pipes is polished, so friction is holding strong.

The way I see it, my options are:

-Brute force the thing apart (already tried, almost broke it)
-Melt the plastic with heat (any tips? It is about 1m long, so it is pretty big)
-Dissolve the plastic (any ideas? Would a normal paint-stripping solvent do anything?)


Thanks alot. This is like a $500 project and I NEED to get it out. In the future, do you think using mold release agent or another lube would help?

Thank you all so much for your help. PLEASE PLEASE PLEASE do not just pass up this thread! ANYTHING would help.

Well that's a hard one. Here is the MSDS for Smoothcast 300: http://www.eagerplastics.com/sc300b.htm "Polymeric Resin" is a pretty generic term so I can't give you anything specific. If I knew what exact polymer it was I could probably give you better information.

Let's just call it "plastic". Most plastics are vulnerable to Keytone solvents. I think the most powerful ketone you can get a hold of is Butanone which is usually called MEK or "methyl ethyl ketone". You can buy it from Amazon or your hardware store.

Here is an example from Amazon:
http://www.amazon.com/Sunnyside-Corp-84732-Methyl-Ketone/dp/B000BZX49I/ref=sr_1_1?ie=UTF8&qid=1322108882&sr=8-1

From the description "Very active solvent with similar characteristics to acetone, but is slower drying than acetone. Primarily used with specialty epoxies and resins." which is a nice way of saying that it will dissolve the[Censored. Please be nice!] [Censored. Please be nice!] out of things.

I have to warn you though, MEK is pretty toxic so you don't want to screw around with the stuff. Wear two layers of nitrile gloves and don't breath the fumes. If you have a an organic vapor respirator use it and replace the activated charcoal cartridge beforehand.

Some plastics and resins aren't soluble in anything at room temperature. In this case you want to get the MEK boiling but you want to do so safely. The best way to do this is to use an electric hotplate outside so you don't have a toxic fume problem in your house. Use a pot of water and float a borosilicate dish (Pyrex) with the MEK in the boiling water. This will prevent hotspots igniting the MEK because you have a water buffer. Put the metal pipes in the MEK and get the MEK boiling. It should attack the plastic rapidly. I have dissolved a number of things this way.

If MEK doesn't work the other solvent to try would be Xylene.

If Xylene doesn't work, if you can get your hards on "carbon tet" https://en.wikipedia.org/wiki/Carbon_tetrachloride or Chloroform or Tetrachloroethylene those are almost guaranteed to work. Write you will first before using them though. Chloroform is the only chemical I have even seen dissolve my HD-PET conicals at room temperature.

Thanks a bunch for the reply.

I think I am going to try a bit of acetone, although I doubt it will be strong enough.

Then I will make a trip to Home Depot and pick up a gallon of that stuff, and try to dissolve it. The outer pipe does have a paint finish that I would like to preserve though, so full submersion is a last-ditch effort for now. Perhaps just some on the inside, I dunno how I will maintain the temperature though.

Does anybody know the melting point of this stuff? I assume pretty high. My original thought was submersion in super-hot water. This is stupid, right?

I really don't want to screw around with any dangerous chemicals.... I can't beleive that I ****** this up in the first place.......

*sigh* thanks again. I will keep this updated with my results.

If anybody wants pics, let me know.

Unicorn.

I don't know the melting point because I don't know the chemical. A lot of polymers have a variable melting point based on the density of the material and the length of the polymer chains. Boiling water is unlikely to be hot enough but if you want to get something really hot without discoloring or warping the metal you can use oil. I use mineral oil (baby oil) which you can get to 300+ Celsius. Vegetable oil is a reasonable alternative. For some perspective, the polypropylene truck strap seals I defeat start to soften at 115c and start to melt at 125c and I think that's on the low-end for most plastics. I have gotten nylon above 200c without it melting.

I don't think Smoothcast has a melting point. It will start decomposing well before it melts.

The pipes are metal, right? You could try using a torch to heat the metal until the stuff burns out. I'm sure the smoothcast would burn/melt/decompose long before the metal starts to melt.