strengthening a plaster of paris bio cast?

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th3 pr3dat0r

New Member
ok,i am planning on sculpting a custom bio on a pepakura P1 file, besides the point, since i am on a tight budget. the stiffest/cheapest material i found was plaster of paris. how would i be able to make it stronger to be more stiffened?
 

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carpe noctem

New Member
hopefully ur not going to wear it right.. it would be too heavy, plaster is a heavy material...in order to be strong has to be thick( heavy) if u put a thin layer, theres no way of making it stronger unless u coat it with something like fiberglass when ur done, and even that if u drop it its gone!!! can u try ( a cheaper way ) paper mache? it will be cheap, it will no doubt be light and wont break if u drop it..... theres a topic here i saw or someone who made a wire frame then paper mache it and it became pretty good.... all u need is newsaper and all purpose flour.. google paper mache images , u find lots of ideas
 

th3 pr3dat0r

New Member
do you mean, like put paper mache slips in the mold? or like grind the paper and mix with glue/water and then brush it in? i was also thinking of casting in hotglue?
i was looking at bondo fiberglass, but i need inexpensive stuff
 

hez1

New Member
OK, couple of things...are you talking about making a mold out of hot glue? That's not a great idea if so. If you must have the least expensive material available, the caulking silicone you can buy from home depot or lowes is a better option. I know there's a huntorial around here on it somewhere, you should search it out. if you mean casting the bio in hot glue...why? It'll flop around like a boned fish.

Second, while it is possible to strengthen plaster of paris, I don't understand why you need to use it. Buy yourself a tub of regular bondo, the standard kind is fine. Then buy yourself some of the bondo fiberglass resin as well. Mix them together in a 50/50 ratio or something similar (you don't need to be exact, it just needs to be a thick but still runny consistency, and don't forget the hardener!) and then pour it into your mold. Slush it round in there until it sets, try and get an even coating everywhere. It will be heavier and somewhat more brittle than using fiberglass or regular casting resin, but it'll work, and all for an outlay of about $24. This is how most of the Halo costumers finish up their pepakura armor. Of course, the brittleness can be solved by using a lot more material, but then it will weigh a ton more...

If you're set on using plaster of paris, you need to buy some cheesecloth. Your local hardware store should have it. Cut it into strips, and mix up some plaster. It should have a nice thick consistency, still fairly runny though and definitely not lumpy. Dip your cheesecloth strips into the plaster mix so they're nice and soaked, and then lay them in the mold. Total cost on that method should run you about $8. If you use this method, congratulations, you will be the owner of the heaviest bio in the world.

:)

Good luck with whatever you choose to do.
 

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crawjaw

Active Member
If you're determined to use plaster you can strengthen it with plaster bandages, cheesecloth, burlap, chicken wire, old bedsheets etc. I still wouldn't use plaster as many have said how heavy it would be, and it would still be brittle although less so than unreinforced plaster. I've used a product called Sculptamold in the past (ready made papier mache) that you mix with water and it can be pressed into latex moulds, or shaped like normal clay. Fairly cheap, and quite strong if reinforced with strips of paste soaked newspaper or wire mesh. It can also be sanded and painted.

Have a look at my Terminator build that details some of the methods you could use. It was constructed with a wireframe, covered in wire mesh, paper strips, Scultamold and then resin. Overkill for what you need but it may give you some ideas. I reckon the chest of my terminator could take my 14st weight if I stood on it although I wouldn't put it to the test.
Terminator build link on Lair
Terminator build link on Terminatorfiles.com

Also check out the Lair for a product called Jesmonite. It is a safe alternative to resin and fibreglass and is supposed to be nearly as light and strong. Obviously dearer than plaster though. This is the method I would use given the choice.

Good luck.
 

th3 pr3dat0r

New Member
crawjaw i was thinking of that but i didnt know how strong it was! but if you say you can reinforce it with papermache i may give it a go, and see how it turns out. i may not start this till nrxt week though
 

crawjaw

Active Member
crawjaw i was thinking of that but i didnt know how strong it was! but if you say you can reinforce it with papermache i may give it a go, and see how it turns out. i may not start this till nrxt week though
I meant use Sculptamold instead of plaster. Bio will be extremely light and fairly rigid. If you poured plaster into the mould the Sculptamold wouldn't be of any real use.
I would try using a thinner mixture of Sculptamold than used for modelling for the first layer, so it picks up the detail. Let it dry a bit then use paper strips at different angles to laminate it then add a thicker mixture of Sculptamold to bulk the piece out. Alternatively you could use layers of old tights/stockings as reinforcing. Just make sure your better half is finished with them. Since the Bio isn't going to be worn it doesn't really need to be that rigid and I'm sure you'll be surprised how strong papier mache can be especially once varnished/laquered.
 

crawjaw

Active Member
Sorry I thought it was to be a static display only. In that case forget about using plaster as it will weigh a ton and be extremely uncomfortable to wear. If you can't afford resin/fibreglass or Jesmonite then papier mache is the way to go. Laminating the inside of the bio with stocking material would also make it more confortable to wear. Alternatively some strategically applied foam would also help.

Plenty of guys on the Lair have made/bought Bios so hopefully someone else will add their help.
 

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