Pros and Cons of plaster cloth or bandages?

dariang

Member
Hey everyone,

TL;DR: What are the pros/cons of using plaster bandage over fibreglass and resin for the shell of the mould? Are there better quality plaster bandages out there? If so, what do you recommend?


Details:
I'm currently working on a Mk VII Iron Man suit and I'm currently doing some moulding of the arm piece. I'm using rebound 40 for the mould. When I made a mould of the helmet, I used fibreglass and resin to make the shell. I just watched a tutorial online and the guy used plaster bandages and it seemed so easy. I just wanted to know if the quality is worse, or if it breaks easily, is it really better, are there specific plaster bandage brands that are better than others, etc... Anything and everything. I see Wal-Mart sells them, but they are like 30 bucks when amazon sells them for about 10 bucks.

Normally I would just buy it and try it, but I thought I would just ask first in case anyone out there had some quick insight.

Thanks!

Link to my build: http://www.therpf.com/showthread.php?t=149096&page=4
 
There are upsides and downsides to plaster bandages. You can generally make a shell a lot faster, a lot cheaper, and a lot easier than when using fiberglass.

However, it is also much weaker, much more susceptible to warping, and most of the time a little heavier. If you're going to be casting two or three pieces, it's probably fine. Anything more than that you'll probably want to spring for the durability of fiberglass. Fiberglass will be much stronger and last through many casting cycles. I've never actually had a fiberglass shell give out before the silicone it's holding.

Gypsona brand is a fantastic plaster bandage and the only one I personally use. It's much stronger than your run of the mill bandages, but as I said they will still break down.
 
I would only use plaster bandages if it's a small mold that only needs one or two runs. I'll make a stronger, cheaper version with burlap and hyrocal or ultracal most of the time.

Fiberglass is a superior material, as Jackson describes, but the main downside is toxicity and cleanup of little bits of potentially itchy fibers, especially if you're not accustomed to the workflow.
 
Durability.

Plaster: Cheap, water activated, non-toxic, easily available, HEAVY, if treated gently, will last for multiple pulls.

Fiberglass: Pricier, toxic chemicals require RESPIRATOR, EYE PROTECTION, and gloves, Weighs much less, very durable and can withstand pressure.

Weight is a big issue if you are going to try and roto-cast the pieces by hand. Any plaster mold bigger than a helmet, and it is too heavy to lift by one person. (OK, with plaster bandage rather than hydrocal, not so much, but you get the point)


In the end, I would say a combination of both for your project. Small molds for arms and hands: Plaster. For the thighs, chest, and larger molds, go with glass.

OH, One more thought for ya: Smooth-On sells a plastipaste that might be a middle ground. It makes shells for molds, and is less work that laminating glass.
 
I'm not sure where you live but here in the US we now have water based fiberglass resins which are non toxic. Do some google searching..
 
Those that I know who have used it say it's no different then polyester resin.

Sent from my SD4930UR using Tapatalk
 
How does water-based resin compare in terms of strength and durability to the traditional toxic stuff?


I have only used a very small amount from a test kit, so I can't say I have too much experience with it. The brand was Aqua-Resin, which to my knowledge is the only US supplier of the stuff, but then again I haven't been really researching the stuff enough to say for sure.

I found in the small piece I test casted with fiberglass support it was comparable to traditional fiberglass resin. Strength and durability wise it seemed just a tad weaker, but nothing you would notice or that would be particularly detrimental.

The problem came in the surface coat. It seemed very prone to chipping and cracking. This could of course be remedied by using an epoxy gel coat, but then you run into the toxicity issues, and I honestly have no clue how well Aqua-Resin would bond to it. It was also on the heavy side, which I believe stems from the powdered component. I believe it is just gypsum powder.

It seemed very similar to UV resin, if you've ever used that.


It's definitely not terrible stuff, and used correctly it could come very close to the quality of tradition resin.
 
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