Recent content by 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!

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

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...

Thanks Danny

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...

Looks fabulous. The photo set showing the work stages is crowned with this 'after' picture. Thanks for the update

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...

Just back from polishing my mould at the workshop and took a picture of my more typical running horses...