Mould advice

Status
Not open for further replies.
K

kernowspread

Member
Mould adviceNearly finished model and trying to get my head round best/most economical way to make a mould.
thinking silicon insert for the enrichment in grp mould rather than full rubber. Anyone got any advice/do's /donts on best way? is thixo applied best way or shuttered and poured?
Any advice would be great, hard when your in workshop on your own with no one to talk stuff through with!
cheers
 
@mikeadams1985 yet again he's the only fiborous fanny i can think off..........................:RpS_thumbup:

Thought this was a thread on condensation and you lured me in.........................:RpS_thumbdn:
 
Last edited by a moderator:
You've kinda done that a bit backwards.
It's. Still workable though.
What you need to do is put a.bpard up against the egg ad dart.

I would run a core over it. Then do a fibreglass case then remove the core. Replace the case (with holes added).and pour the silicone in.

Grp and silicone miulds more hassle than it's worth.
 
You can cover the model with some wet newspaper. Until it's smoothed out and all under cuts are smoothed. Then run a profile over the top. Let that dry and shellac and wax it. The take a grp. Mould. Off.it. then remove and remove the core.and news paper.
Then pour your silicone as usual.

That model is fantastic btw
 
That is a great tip mike, much appreciated. Couldn't think how to core it except in clay, and that wouldn't work with the Grp.
Do you think 10mm thickness is about right for the pour to keep a good shape?
Thanks mate my brother hand carved the e&d and I modelled the frieze, it's gonna be a nice one , just don't want to cock up the mould!
 
mikeadams1985 said:
You can cover the model with some wet newspaper. Until it's smoothed out and all under cuts are smoothed. Then run a profile over the top. Let that dry and shellac and wax it. The take a grp. Mould. Off.it. then remove and remove the core.and news paper.
Then pour your silicone as usual.

That model is fantastic btw
Click to expand...
Mike is spot on , although the initial cost of the silicone may seem expensive , it is the best option in the long run,with a couple of tracks in the core to ensure the rubber sits back into it. And keeps the casts straight , nice work , is it matching existing or a stock mould



Irish Fine Art Plasterwork | Irish Fine Art Plasterwork
 
Of course I'm right frank :) haha
Before you do pour the mould. I can see the repeat on the swirl enrichment. Is that just visual.or can you feel it?
 
rugbymad would like to help, if more info was on offer, maybe local product names are a wee bit different but sure they mean the same, if you are trying to take impression of enrichment only it is a simple process, if trying to reproduce whole piece it is even more easy , if I can help in any way let me know, I don't want to sound a smart arse to anyone but do like to help, cheers from rugbymad
 
rugbymad said:
rugbymad would like to help, if more info was on offer, maybe local product names are a wee bit different but sure they mean the same, if you are trying to take impression of enrichment only it is a simple process, if trying to reproduce whole piece it is even more easy , if I can help in any way let me know, I don't want to sound a smart arse to anyone but do like to help, cheers from rugbymad
Click to expand...

You smart Arse..................................:RpS_wink:
 
FrankNewman275 said:
Mike is spot on , although the initial cost of the silicone may seem expensive , it is the best option in the long run,with a couple of tracks in the core to ensure the rubber sits back into it. And keeps the casts straight , nice work , is it matching existing or a stock mould



Irish Fine Art Plasterwork | Irish Fine Art Plasterwork
Click to expand...

Thanks Frank its a bit of both, client wanted something fancy for large a drawing room that had lost its original. Enrichments are from another that we are due to replace so hopefully use it again.
 
Fibrehand7 said:
Ok am I right - put the cornice in the valley, lay the wet newspaper over entire cornice and then a slab of clay over entire cornice as a core and make clay nice and smooth , make track grooves on clay, and produce fibreglass jacket over the clay, then jacket is dry, remove the jacket, clay and newspaper, make couple of holes in jacket and large hole for the funnel , put jacket back and pour silicone in until all comes out of holes?
Click to expand...

It's a run core being advised Ryan rather than clay if I've understood right?
 
Good thread. I don't do cornice but use similar processes exterior to repair masonry, mainly sandstone. I use rtv 134 silicone with thixo for exterior vertical etc & found the moulds quickly losing shape even with silicone register keys stuck on, with plaster paris scrim casing for insitus. Maybe just less than 10mm silicone. A cheap p/paris casting left in the mould gave it longer life but I wasted a bit of silicone & money before I sussed this :-)
 
kernowspread said:
View attachment 3662Nearly finished model and trying to get my head round best/most economical way to make a mould.
thinking silicon insert for the enrichment in grp mould rather than full rubber. Anyone got any advice/do's /donts on best way? is thixo applied best way or shuttered and poured?
Any advice would be great, hard when your in workshop on your own with no one to talk stuff through with!
cheers
Click to expand...

Just wondering why you never left the ends (300mm) blank ?
 
perlite said:
Good thread. I don't do cornice but use similar processes exterior to repair masonry, mainly sandstone. I use rtv 134 silicone with thixo for exterior vertical etc & found the moulds quickly losing shape even with silicone register keys stuck on, with plaster paris scrim casing for insitus. Maybe just less than 10mm silicone. A cheap p/paris casting left in the mould gave it longer life but I wasted a bit of silicone & money before I sussed this :-)
Click to expand...

That's a good shout that perlite, keeping a cast in the mould for storage .
 
I would just mitre it and free hand anything that didn't marry up right?

The run core Ryan is just running another profile over the top.instead of clay. Gives a more.even finish
 
Fibrehand7 said:
What I have thought, so that enrichment can get mitred nice and tight. Thanks for pointing it out for us to learn. What do you think of my previous post by having both rigid and flexible reverse mould as can save money on rubber?
Click to expand...

I wouldn't mess around Ryan I'd just go rubber
 
The news paper is just a barrier between the model.and the plaster core and to smooth over the enrichment so the plaster doesn't lock. Doesn't have to be anywhere near an inch thick
 
Hi kernowspread
here is an alterative method; the cornice is placed in a trough, all the cornice is shellacked- a long the edges of the enrichments place lathes to form a fence, cold pour is poured over the enrichment allow to set.Carefully remove the lathes without disturbing the rubber- grease the cornice
Mould advice

a cast is taken from the cornice encasing the cold pour rubber. on setting remove cast from the trough (insertion mould )
Mould advice
 
Size of them stroke offs!! ahaha

Ryan you havent saved that much really, the thickness of the rubber there, if you did a case and poured it at a constant 10mm thick it would probably work out the same.
 
mikeadams1985 said:
Size of them stroke offs!! ahaha

Ryan you havent saved that much really, the thickness of the rubber there, if you did a case and poured it at a constant 10mm thick it would
probably work out the same.
Click to expand...

hi Mike the photos of the insertion mould are from one of students - it was a project he was working on----- (puddove)
 
Status
Not open for further replies.

Share this page

Back
Top