New member introduction; main interest is fibrous plaster mouldings.

[DaveCP]

Welcome along @DaveCP

Thanks Danny

 

[DaveCP]

let it heat up as it sets the heat will melt the releasing agent allowing for a easier stripout/also suggest u use a rubber grouter to clean off your spillage on the wings that scraper is stripping off the shellac

I tried a couple more casts on that same reverse mould today; they were releasing cleanly but still cracking no matter how careful I was. I was feeling for when the plaster was hottest but noticed it was hardly warming up at all. I went and got a new bag of plaster, by chance newly packed and so as fresh as it comes. But, it hardly heated either. My workshop is freezing cold at the moment and this is a very small casting so I think the heat is dissipating too quickly to warm the cast up. I'll try a larger mould next time to see if the bigger volume of plaster gets some heat going.

Although the plaster set seemingly well, do you think failing to warm might make it more prone to breaking when I demould or am I just being ham-fisted?

 

[The Hobo]

I tried a couple more casts on that same reverse mould today; they were releasing cleanly but still cracking no matter how careful I was. I was feeling for when the plaster was hottest but noticed it was hardly warming up at all. I went and got a new bag of plaster, by chance newly packed and so as fresh as it comes. But, it hardly heated either. My workshop is freezing cold at the moment and this is a very small casting so I think the heat is dissipating too quickly to warm the cast up. I'll try a larger mould next time to see if the bigger volume of plaster gets some heat going.

Although the plaster set seemingly well, do you think failing to warm might make it more prone to breaking when I demould or am I just being ham-fisted?

what kind of plaster u using

 

[DaveCP]

what kind of plaster u using

Dental plaster (fine mesh pop). It usually gets hot but I think the combination of cold workshop and small volume are conspiring to keep it cool. I think I need to work on my de-mouldng technique - I work a spatula under the cast at an end and wedge it in until the product pops off but it tends to crack a few inches further along.

 

[The Hobo]

Dental plaster (fine mesh pop). It usually gets hot but I think the combination of cold workshop and small volume are conspiring to keep it cool. I think I need to work on my de-mouldng technique - I work a spatula under the cast at an end and wedge it in until the product pops off but it tends to crack a few inches further along.

I think dental plaster maybe to brittle no give in it /have u laths inside it ? best tip is for u get some casting plaster try SPECIAL PLASTERS BIRMINGHAM also try jute scrim and laths heat of workshop is not an issue mine is boltic but stuff still heats

 

[DaveCP]

I think dental plaster maybe to brittle no give in it /have u laths inside it ? best tip is for u get some casting plaster try SPECIAL PLASTERS BIRMINGHAM also try jute scrim and laths heat of workshop is not an issue mine is boltic but stuff still heats

Thanks, I'll try that place. Reassuring to know mine's not the only cold workshop.

 

[The Hobo]

Thanks, I'll try that place. Reassuring to know mine's not the only cold workshop.

if u want a cold day come up to me I work in a old milk byre damp as fck gets little sun /and the wood stove fcked up that's why its boltic

 

[DaveCP]

Mine's in an old farm unit; part concrete block, part steel panel, with asbestos-cement roof. It's colder inside than out for most of the winter - on a sunny day I work outside for a warm up! I'm looking forward to warming my fingers in a bucket of fine casting!

 

[Deleted member 32554]

Mine's in an old farm unit; part concrete block, part steel panel, with asbestos-cement roof. It's colder inside than out for most of the winter - on a sunny day I work outside for a warm up! I'm looking forward to warming my fingers in a bucket of fine casting!

Electric blanket ?

 

[The Hobo]

Mine's in an old farm unit; part concrete block, part steel panel, with asbestos-cement roof. It's colder inside than out for most of the winter - on a sunny day I work outside for a warm up! I'm looking forward to warming my fingers in a bucket of fine casting!

sounds like mine but mine built with 2 foot of stonework