[eric2011 (OP)]

Hi peips.How to keep molten plastic  in liquid state foor  long. After melting plastic in a crucible and want ti pour it in a wooden mold i want it ti cool withoiut solidifying in the crucible before pouring in the mold. So hoe how or what to mix in si the molten plastic can stay liquid even if it starts ti cool?

[paul cotter]

Most substances that require heat to melt will solidify on cooling. What kind of plastic are you using? Bear in mind that some plastics will decompose before melting' Generally if you have a plastic that can be safely melted it will solidify when cooled and I don't think there is any way to prevent this. Don't attempt to melt polystyrene or polymethylmethacrylate(plexiglass) as these will depolymerise into styrene and methylmethacrylate respectively, both of which are irritant substances. Much more dangerous would be an attempt to melt Teflon as it does not melt and decomposes releasing a deadly gas.

[alancalverd]

Generally if you have a plastic that can be safely melted it will solidify when cooled

I think that is the definition of a thermoplastic!

Anyway, the trick is of course to heat it to well above its melting point and continue to heat both the crucible and the mould whilst making the transfer.

[vhfpmr]

Much more dangerous would be an attempt to melt Teflon as it does not melt and decomposes releasing a deadly gas.

Is it harmful? The advice I recall from my Health & Safety course when I started work was that if you catch a fragment of PTFE swarf on the red end of your fag it'll make you feel like you have malaria for a while, but there's no lasting damage. That might just be because a bit of swarf on a fag is a small dose, of course.

[paul cotter]

Perfluoroisobutene is a breakdown product of decomposing Teflon(ptfe) and is extremely toxic and acts similar to the war gas carbonyl chloride(phosgene). As far as I remember it is more toxic than carbonyl chloride but I may be open to correction on this. The effect of these substances is pulmonary oedema and one drowns in one's own exudate.

[eric2011 (OP)]

how to prevent mokten plastic from sticking to wood? Cooiing greese, vasejine?

[alancalverd]

Use a really dense wood like ebony or surface-char and polish some seasoned oak. Preferably, use a metal mould.