Tuesday, 20 May 2008

Mystery material

The bed material I am using for ABS works very well but the problem is I don't know what it is. My wife bought it for 10p when I was trying lots of things for HDPE and was disappointed when it did not work. She is now delighted I found a use for it as she loves to get a bargain.

It originally looked like this :-

It is about 3mm thick. Most of that is the plastic backing. On the front is printed paper, stuck on with a double sided sticky film and covered with single sided sticky film. This can be peeled off to just leave the back material so both sides of that can be used.

Here is a bit I destroyed developing rafts: -

It will bend a little but then it snaps, as you can see, when I pulled a raft off that was stuck too well.

I normally use this flowchart to identify plastic but it fails with this material because I think it is a polymer with a fibrous filler, possibly paper.
  • It melts with a low temp soldering iron so is not a thermoset.
  • It floats very well but it is not PE or PP, so that is probably due to a filler.
  • It does not burn well and is self extinguishing.
  • It gives black smoke and if anything has a yellow flame.
  • It does not drip.
  • The smoke has some odour but I don't recognise it. I don't know what phenol smells like though.
So perhaps it is PPO and a fiber. If anybody knows where I can buy it from I will be very grateful. It is quite reusable but I expect it will need replacing sometime and other people want to use it.


  1. Might it be expanded PVC? That matches the physical characteristics, but I'm not sure about the chemical ones (your spreadsheet claims that PVC burns with a white smoke, not a black one). The material is reasonably common, at least on this side of the pond. It is often used as poster/sign board, and is available in a variety of thicknesses from most plastics supply shops.

  2. I don't know what the plastic is, but there is a UK company 'Signs & Plastic Products Ltd.'‎ at:

    whose contact info is:
    Bright Street
    Middlesbrough, Cleveland, TS1
    01642 246 087

    and they hopefully will know a lot about sign plastics.

  3. have encountered something with similar properties in d+t back in school believe the material was foamex.
    teh other point that leads me to this conclusion is this material is often used for trade stands

  4. scopeuk,
    I don't think it is foamex because it is not foam like. I.e. it does not appear to have air in it. I think it is PVC mixed with a fibrous filler like paper.

  5. Hi

    I am working with making signs and other profile products, and from your picture that sheet looks a lot like a sheet material named "Forex Classic" that we use a lot to put printed vinyl foils on, just like the one your wife bought...

    The distrubutor we buy from is http://www.schneidler.se/

    Forex Classic is a medium density extruded PVC sheet material.

    3mm is the most common thickness to use for signs like that one.

    // Erik aka Meduza

  6. Thanks Erik,
    That does look like it may be the same stuff. Any chance you could post me a small off cut to be sure? I will refund your postage.

    Interestingly I have been using the same piece for six months now. Although it looks quite a mess it still functions well. The raft evens out any irregularities in the surface.

    That means the piece my wife bought will last for at least another 4 years, barring accidents!

    Short-sightedly I cut it into HydraRaptor sized pieces so I cold do with a new sheet for my Darwin.

    Wade has reported success with acrylic, which I yet to try, so I may try that first on my Darwin.