Model Boat Mayhem

Technical, Techniques, Hints, and Tips => Other Technical Questions... => Topic started by: colin-stevens on September 27, 2007, 02:39:20 pm

Title: using plaster as a mould
Post by: colin-stevens on September 27, 2007, 02:39:20 pm
had to think of a subject that didnt include fibre glass in the title, althought thats where i shall eventualy end up, but been well covered.
ok, any one used plaster, under any desctription, to make a mould. any hints/tips suggestions?
colin
Title: Re: using plaster as a mould
Post by: Guy Bagley on September 27, 2007, 03:31:23 pm
yup, i made a hull in 2 halfs. it was a fantasy style vessel, , the original was sculpted and then i made a mould in plaster, i used  a hard dental style plaster,

i then laid up a GRP hull from the plaster mould, , finer details such a hull plate lines were generally ok, one of two sections  of plate lines were not perfect, but were sorted with dremel and tools !

downside of plaster  is they are generally only any good for one GRP hull - so if you wish to make several the quality drops off quickly, small details may be compromised,

you must use release agents- the righto nes in the right quantity- plaster is very porous !

positives are you can layup some unusual shapes with a plaster mould- inlcuing major undercuts the mould can be split/ broken/ cracked off  - hence plaster moulds are often referred to as a waste mould.....

plaster is cheap and can set quickly

ideal for mock up or test moulds.......

 good look
Title: Re: using plaster as a mould
Post by: colin-stevens on September 27, 2007, 04:26:20 pm
yer, just what i figured. will get supplies from "proper suppliers" and with luck they will supply the correct stuff.
this damned boat (Atlantic 75) is now costing a fortune, only meant to cheap build.
Title: Re: using plaster as a mould
Post by: Telstar on September 27, 2007, 05:09:22 pm
Hi Colin
Just today I happened on a site
http://www.resin-supplies.co.uk
I was after expanding foam to pour in a hull to give buoyancy. But they do all kinds of resin and mould materials.
The chap I spoke to was brilliant he was very helpful and could suggest what was best to use for my perpose even though any order I would make would be for small quantities.
Probably worth a look
Cheers Telstar