Polystyrene

[Rapporman]

I have lined a case with a polystyrene block with cutouts for various tools etc. What can I seal the polystyrene with to stop it crumbling. Solvent based products will probably melt it and I assume waterbased products will not adhere as polystyrene is waterproof. Any suggestions?

 

[regsmyth]

I would line it with felt or some other soft layer. Don't use solvent glues that will melt the polystyrene.
Polystyrene is very weak and won't last long like this unless protected. You should have used foam rubber.

 

[Rapporman]

Many thanks for replying Regsmyth.

I tried using foam but the only block foam I could get locally was the 'soft' type suitable for cushions etc and although I could cut down into the foam, I could not sculpture out the base of the recesses without making a real pigs ear of things. I thought of using two sheets, one to form the base and cut the recesses out of the other top sheet to avoid sculpturing but the recesses needed to be at varying depths so I scrapped that idea.

The next best material was therefore polytyrene which I got from my local builders merchant and I found it fairly easy to sculpture out the recssess with relative accuracy, so I am still hoping someone will know how to seal - as you say - this fragile material.

 

[ColJack]

make a negative with plaster of paris, then gelcoat it and fiberglass it..?

 

[Rapporman]

Many thanks Coljack but that solution is way over the top for my purposes. I just wanted to stop some tools falling about when I carried the case and if I had to go to those lengths, it would pay me to buy a purpose made toolbox. As it is I am just looking for a cheap way of restraining a few tools, so I am still hoping someone will know how to seal polystyrene. If the answer is 'no can do', I'll give up the idea but I really can't beleive it is impossible to seal polystyrene!!

 

[ColJack]

aparently Gesso works well, along with sanding sealer.. ( gesso is what srtists seal a canvas with before painting on it.. so try an art store.. )

 

[wotan]

PVA adhesive brushed on might work, can't imagine this destroying polystyrene.

Wotan

 

[Rapporman]

Many thanks Wotan and Cojack. I had some PVA so used that. I applied two neat coats and it has put a hard skin on the polystyrene, especially around the edges which tended to crumble more than the flat surfaces and did not have an adverse effect on the polystyrene. I 'm not saying it is a permanent solution but will do for now. Thanks to you both.

 

[wotan]

Many thanks Wotan and Cojack. I had some PVA so used that. I applied two neat coats and it has put a hard skin on the polystyrene, especially around the edges which tended to crumble more than the flat surfaces and did not have an adverse effect on the polystyrene. I 'm not saying it is a permanent solution but will do for now. Thanks to you both.

You are most welcome.

 

[JohnD]

polystryrene is quite weak and crumbly.

Another suggestion: Use Expanding Foam. You can put the tools on a flat surface and pack thick polythene or other membrane over them (to prevent them being stuck to the foam) put the Expanding Foam over the top. This will also stick to your toolbox (unless you line it) and make it all more rigid.

If you have not used expanding foam before, do it where the mess will not matter. It will stick to clothes, fingers, gloves, hair, skin, eyeballs, shoes, carpet, concrete etc, and if you walk on it it will tread in. I use clingfilm and masking tape to protect nearby surfaces. Have a supply of disposable gloves so that you can change them as soon as they get foam on them. Wear clothes you can throw away. A water mist sprayer helps it cure faster and form a non-sticky skin.

 

[TicklyT]

If all else fails, http://www.efoam.co.uk/Spackaging.php may be useful.