Ama Menec on thu 16 nov 06
I wondered if any Clayarters have any experience of making press moulds
using a combination of plaster and fibreglass? Or other non-cellulose fibres
such as polypropylene.
I've just made a life-sized 4-piece press mould using prestia creation
plaster and both of the above fibres. It seems to have worked well and is
showing no signs of warping, relatively lightweight and relatively
manageable by one person on her own. The fibreglass was nasty to use, (loose
non-woven matting torn into hand-sized pieces and layered on having been
dipped in plaster first), and bits of it are still periodically embedding
themselves in my hands and forearms. I'm debating using polypropylene
matting instead of fibreglass matting next time, but am not sure if it would
be as strong. Plus the polypropylene fibres tend to make the mould a bit
fizzy in places and are best trimmed off by melting them back with a match!
I'd be really interested to hear from any ceramicist who has worked in this
way to make large light-weight moulds and share experiences and technical
tips. Many thanks,
Ama Menec, Totnes, Devon, UK.
www.amamenec.co.uk
D. L. Engle on thu 16 nov 06
Hi Ama,
I've used a Forton product called FGR-95 that is formulated to be used with
fiberglass. The fiberglass that I use with it is called 3/4 vale. It is neat
and easy to work with as it is a fine mesh in thin sheets. It comes in a
roll, the sheets that you are going to use are cut to size, the layers
teased apart and laid in place on the mold. The layers are a little bit
sticky so almost none of the fibers come loose. Then the very slow setting
FGR-95 (actually they call it a gypsum cement but it looks like plaster) is
stippled on. This must be weighed when mixing, 30 parts water to 100 parts
FGR-95. Layering this up to a thickness of about 1 inch or less I've made
very strong and large lightweight casings for RTV molds and also plaster
press molds for clay. The plaster press molds have first a layer of regular
plaster then the multiple layers of FGR-95 with fiberglass on the outside.
The FGR-95 is available from places that sell a good selection of plaster
products and the fiberglass veil I get from a sculpture supply store.
Hope this helps, let me know if you need any additional info.
Best Wishes, Debbie
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of Ama Menec
Sent: Thursday, November 16, 2006 12:18 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Plaster and fiberglass
I wondered if any Clayarters have any experience of making press moulds
using a combination of plaster and fibreglass? Or other non-cellulose fibres
such as polypropylene.
I've just made a life-sized 4-piece press mould using prestia creation
plaster and both of the above fibres. It seems to have worked well and is
showing no signs of warping, relatively lightweight and relatively
manageable by one person on her own. The fibreglass was nasty to use, (loose
non-woven matting torn into hand-sized pieces and layered on having been
dipped in plaster first), and bits of it are still periodically embedding
themselves in my hands and forearms. I'm debating using polypropylene
matting instead of fibreglass matting next time, but am not sure if it would
be as strong. Plus the polypropylene fibres tend to make the mould a bit
fizzy in places and are best trimmed off by melting them back with a match!
I'd be really interested to hear from any ceramicist who has worked in this
way to make large light-weight moulds and share experiences and technical
tips. Many thanks,
Ama Menec, Totnes, Devon, UK.
www.amamenec.co.uk
Snail Scott on fri 17 nov 06
At 08:17 AM 11/16/2006 -0000, you wrote:
>I wondered if any Clayarters have any experience of making press moulds
>using a combination of plaster and fibreglass? Or other non-cellulose fibres
>such as polypropylene.
I've used 1/2" (1cm+) nylon fiber
in press molds. Worked pretty well,
though any damage had to be de-fuzzed,
or it would bind the clay to the mold.
-Snail
D. L. Engle on fri 17 nov 06
Hi Snail,
Have you found a source of pre cut nylon fibers or are you having to cut up
ropes?
Thank you, Debbie
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of Snail Scott
Sent: Friday, November 17, 2006 9:28 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Plaster and fiberglass
At 08:17 AM 11/16/2006 -0000, you wrote:
>I wondered if any Clayarters have any experience of making press moulds
>using a combination of plaster and fibreglass? Or other non-cellulose
fibres
>such as polypropylene.
I've used 1/2" (1cm+) nylon fiber
in press molds. Worked pretty well,
though any damage had to be de-fuzzed,
or it would bind the clay to the mold.
-Snail
Snail Scott on sun 19 nov 06
At 04:37 PM 11/17/2006 -0800, you wrote:
>Hi Snail,
>Have you found a source of pre cut nylon fibers or are you having to cut up
>ropes?
Ack! had a student who tried that once;
don't go there! Most ceramics suppliers
stock fiber as a regular item. If your
local one doesn't, try mail-order. Nylon
fiber weighs almost nothing, so shipping
is very reasonable. A little fiber goes a
long way when mixed with either clay or
plaster, too, so you don't need lots of
it.
-Snail
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