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GASANT
17-04-2012, 10:06 AM
Hi
What polystyrene hardening product can I use to create a stone like shell over polystyrene to protect it from being damaged outdoors. I have surfed the internet but products so expensive and in my case import and shipping fees pushes the price way out out of my budget.

Perhaps there is someone who has a home made product to help me achieve my goal.

Thank you
Best of luck to you.
Gasant

georgetheforge
17-04-2012, 12:54 PM
Hi Gasant-

There's a number of ways to do this-! depends on what you're doing with the pieces really-

The BEST stuff is called HardKote- Which is available here- http://www.flints.co.uk/acatalog/Paint_Plus_Hard_Kote.html

its good stuff and I've used a fair bit of it before, it can be watered down a bit to make it go further and looks like a slightly rendered sandy finish-

i used it on this-


http://youtu.be/8DnvJg90AT0

and was fairly hard wearing apart from the kids poking pens into it...

or theres foamcoat which is smoother-

for a cheap alternative, you can scrim it so like papier mache but with muslin, with loads of pva to create a shell, the paint and seal with a good waterprrofing varnish/ glaze-

gimme a shout of you need any more help/ pointers.

George

Musht
17-04-2012, 02:39 PM
Lovely work George :-) Not the only one here to learn about CNC for scenery and signage then:-)

Literally just been looking at foam coatings, and log in here to find the very subject come up ,coincidence is a strange thing...

Jesmonite is one of the big brands in this area;

http://www.jesmonite.com

Rosco Foamcoat is another big name

http://www.rosco.com/uk/scenic/foamcoat.cfm

Interested if you have had any chance to compare them with Hardkote anytime, George?

Then there is the U.S. variants , rubberised looks useful ;-)

http://www.sculpt.com/catalog_98/powertools/hot_wire.htm#foamcoat

http://www.fxsupply.com/materials/foamcoat.html

After a chat with a prop maker a while back , he suggested looking at Venetian Plastering and Stucco....a watch of youtube might spark some ideas...

His experience was that using ordinary plaster with large amounts of PVA, building adhesive, in mix was pretty much functional as Jesmonite at ,er, substantially lower cost.

Haven`t yet had the chance to experiment, but the couple of things to change in the mix are the type of plaster, things like Hydrocal can be very hard and Venentian plaster mixes can contain marble dust and other fillers changing the properties.

PVA is strong and cheap , number of foam coats mention polyurethanes, water soluble polyurethane resins aren`t cheap but as varnishes have outstanding wear properties.

For long lasting outdoor use, guessing moving into cement rather than plaster based coatings.

Pulhamite was cement based with added ceramic, ground up pottery rejects, sure the Pulham Brothers would have been using polystyrene as a base if had been available at time:

http://pulham.org.uk/

http://www.english-heritage.org.uk/publications/durability-guaranteed-pulhamite-rockwork/

The ultimate artificial statue stone was probably Coade Stone:

http://en.wikipedia.org/wiki/Coade_stone

Cheers
Adam

lighting tech and artificial water fall enthusiast

georgetheforge
17-04-2012, 03:35 PM
Hey Adam-

yeah I'm dipping my toe in CNC-! wondering if it's worth it time-wise/ cost-wise!

Where do you work?

It's a tough one re the comparison as a tub of hardkote is 70 odd quid and covered the pumpkin so in my view pretty good value... its a bit 'crispier' than foamcoat, and leaves a stone effect finish which i think Gasant was after- and i couldn't push a finger through it-!

foam coats nice stuff but a pain in the arse to sand to get really smooth. Saying that Alasdair from Flints did a seminar thing spraying it through a SATA pressurized pot on a spray gun, and it was pretty slick. nice if you've got loads to do as it goes on super smooth..therefore no sanding!!

Forgot about jesmonite... could be a good one.

G

Musht
18-04-2012, 03:25 AM
>>yeah I'm dipping my toe in CNC-! wondering if it's worth it time-wise/ cost-wise!

Kind of figuring knowing nothing was going to be a bad place to be in next few years ;-)

Its great if you need more than one of something or same thing repeated in different scales, with things like your Pumpkin , guess a talented sculptor is a going to be quicker and probably cheaper ;-)

National seem quite keen on theirs

http://www.nationaltheatre.org.uk/38416/scenic-construction/cnc-machine.html


>>Where do you work?

For myself nowadays, LED lighting for a variety of things, shop and bar interiors mainly and occasionaly theatre and rock`n`roll, it pays the bills.

Started looking at CNC for panel cutting and PCB milling and then started looking at foam cutting etc etc....

http://3dcutting.com/

occurs to me could probably sacrifice some rigidity for size if designed to cut foam and not alloy.




>>It's a tough one re the comparison as a tub of hardkote is 70 odd quid and covered the pumpkin so in my view pretty good value...

Thats impressive coverage , more tha would have thought , thanks.

>>its a bit 'crispier' than foamcoat, and leaves a stone effect finish which i think Gasant was after- and i couldn't push a finger through it-!

You need to be under 10 to get something through it ;-)

>foam coats nice stuff but a pain in the arse to sand to get really smooth. Saying that Alasdair from Flints did a seminar thing spraying it through a SATA pressurized pot on >a spray gun, and it was pretty slick. nice if you've got loads to do as it goes on super smooth..therefore no sanding!!

Only thng with spraying, loads of clean up, the guns the pots , the collatearl damage..great if have load to cover though.

>Forgot about jesmonite... could be a good one.


For the OP another couple of recipes:

http://www.controlbooth.com/forums/scenery-props-rigging/5128-vans-super-scenic-dope-recipie.html , latex in American means synthetic latex, water based acrylic.

http://www.game-terrain.info/articles/goop.html

Cheers
Adam


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