Expanding Polyurethane Foam - Release Agent

Line the piece of cladding with cling film may work?

I think I would go for slightly thicker polythene sheet (in one piece). Were you planning to let it mould over the pipes too? Does it matter if it sticks to the MDF, so long as the MDF and foam come off as one piece?

It won't stick to polyethylene film, as such. Wrinkles and folds will hold the film on the foam. Just leave the film in place. Beware: one hole, and you will bond everything together.

Also:

If someone would remind me how to upload photos to the Wiki, I could do that...

Thomas Prufer

Thicker polythene (than clingfilm) and a quick blast of pledge before putting the foam in would be my choice if I really didn't want it to stick to stuff that was already there. Be aware that the expanding stuff is very keen on expanding and if it can't get out from a space througha hole will deform whatever it is inside making it bulge .

Also the solvent in it will melt some plastics...

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Butter? Might pong a bit after a while though! How about lining the area with cling film or something similar before you squirt? Brian

It needs to go around the back of the pipes, so don't want it to stick to the cladding. Cooking foil might be an alternative (comments about cling film dissolving noted).

It says on the can that it's ok to use on electric cables, but is it really (if it will dissolve some plastics)? Might have to put something over the cables.

Test it on some spare cable. My instinct is that it won't touch PVC at all but will dissolve/destroy expanded polystyrene very quickly indeed.

Sounds like a recipe for damage. The trouble with these expanding foams is they set solid THEN they expand forcefully in all directions.

NT

The foam needs moisture to expand and set. So it won't work. You can spray some water into the void before the foam but the results aren't very neat. Boats/cavity walls etc use two component stuff you have to mix. In practice it's mixed in the spray gun at the nozzle.

Would a dense wool type of thing not do a similar job?

try dried PVA

ISTR that is used at least for polyester resin

Obviously test first.

My recent experience with a one part x50 expanding foam from a gun was that the resulting foam wasn't particularly dense or strong and I guess that further expansion would have been contained if the former was reasonably stiff and was securely fastened down.

I will admit that I could see where all the foam was going and I did have a few test squirts to see how much it would expand.

Don't the one part expanding foams come in different expansion versions?

they must, the last ones I used expanded with some serious force.

NT