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!
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...
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...
Following your advice Hobo, I made some progress today.
I ran a small reverse mould in plaster, gave it one coat of shellac and used your suggested mix of lard and cooking oil as release agent. I did 1:1 and warmed it by putting the pot in boiling water until it mixed nicely. I used one brush...
Really useful, thanks. I would never have thought to put shellac on that early - I'm really pleased to have found this site.
Time to sleep, thanks again.
Thanks. The pale brown colour is the shellac put on immediately after running? Just a single coat? Sorry for all the questions but this is really helpful!
That's certainly something I've not tried, thanks! When you say while the (mould) plaster's warm, do you mean immediately after setting - so still damp? I didn't know shellac would take on damp plaster but that would be excellently fast and what I'm looking for. I've tried lard and oils but not...
Yes, that's solid plaster, no lath or scrim - it stayed on the shellac running bench while it was glass fibred and was obliterated getting it out of the fibre glass.
I couldn't post the youtube video but if links show up, this one shows the 'wet' technique I want to learn (plaster-off-plaster)...
Don't be sorry, I really appreciate discussion.
I've been trying to release from plaster reverse moulds. The moulds are 'green' and still damp rather than dried and shellaced. I only recently discovered this was possible, having seen Brazillian plasterers making corninces with back moulds in...
I just found a couple of photos that betray the order of things. This one is the same bench-run plaster pattern (after cleaning up!) showing the back of the cornice - which is deep and would (I think) need to have come out of a flexible mould had it been taken from a mould:
This plaster...
If only! I have yet to release a product from any of my attempts at reverse moulding without damaging them. The reason it's clean is because I took photos afterwards, having cleaned everything up (not yet proficient enough to faff around with a camera while plaster is setting). Yes, the finish...
That one's a little over-engineered. My recent ones have been much more rough and ready. I keep thinking a nice one with nuts and bolts could be used with different profile blades but never seem to get it right, it's always easier to knock a quick one up for the current job.
Excellent project!
I visited it a few years ago and it was full of lawn-movers and maintenance equipment, neglected and looked like it would decay into oblivion. I think the council used it to store maintenance stuff then. It had obviously once been a beautiful building and it's wonderful to...
Ha! The only work I moan about is stuff I've done without engaging the brain first and messed up - thankfully rarer since I've mastered the art of a slow start and plenty of tea!
I haven't tried any latex or silicone mould making yet, maybe when I have to do something irregular. The simplicity of plaster reverse moulds pleases me (or will do when I master releasing them!).
I'm currently experimenting with reverse moulds and have been shaping the backs using a profile rule made of 3mm ply shaped to the required back and sanded smooth - wooden version of the plastic one shown in mikeadams1985's post above. I hold it with a drag angle of about 30˚ and pull it over...
looks like scagliola/terrazzo, possibly formed by mixing clay brick dust (crushed by hand with a hammer) mixed with lime (to make it hydraulic) and some marble chips for decoration. The backing being lime/sand mortar. The marble chips are shaped to the surface but may have been soft enough for a...
Inspirational, love it and enjoyed the photos.
I've never seen that orange flexi-curve before, has it a name? I'd like to get one. Also, is it mini castors I can see on the side of your horse?
Hello all,
I'm here to learn and hopefully share difficulties I encounter on my journey to discover more of the wonderful world of fibrous plaster. I've been very impressed with the discussions I read before my un-registered views ran out. I'm mostly interested in cornice work and have some...
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.