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Some More Mould Making, Ceramic Shell and Lost Wax

Materials, products, processes, suggestions and tips involving how sculpture is made.

Some More Mould Making, Ceramic Shell and Lost Wax

Postby mantrid » Sun Jun 26, 2011 3:01 am

Ive been doing a couple of sculptures lately a small piece of a woman with a towel and a larger more complicated owl in flight. The owl will be challenging to make a mould from due to the wings and claws. I think I will need about 5 separate molds for the two wings, two claws and the body. The woman I am almost ready to cast as it was a simple two piece mould and only about 18cm high with base built in (no stone work required). This means I can make them relatively cheaply with less labour so hopefully they will sell. As usual I have shown the process in pics and hopefully it may help some of you considering lost wax and ceramic shell.

The owl still in pieces. I will photo the process of casting the owl when I get around to it. Still not quite happy with it at the moment
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Towel girl. I cheated a bit with the towel instead of sculpting it as it was so small I dipped kitchen paper in liquid wax and folded to shape. There were things that weren't quite right and some modifications were made before mould making (hair, ears)
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Base not quite finished, replicating a tiled floor.
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The process
A simple two piece silicone mould with two piece plaster mother mould

Clay walls in place for front side. The vertical wall is not critical but is just to give a neat edge to the rubber
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Silicon rubber poured
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Vertical section of wall removed and the scraggy bits being trimmed with a blade
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Trimming complete
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Front part of plaster mother mould applied and in process of shaping while still damp (easier to cut)
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Turned over ready to start on the back. You can see some extra blobs of clay pressed around the legs to give extra support for the clay forming the wall
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The bulk of the wall removed. Some sticks to the sculpture.
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The remaining clay (water based) is easily washed of in a bowl of water with the aid of a soft brush. The oil based clay of the sculpture is uneffected. If the sculpture was water based clay I would use a release agent and be more tidy with the back of the wall so it would be easier to remove. The outer part of the plaster which overlapped the edge of the clay wall is shaved down to the level of the silicone
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A vertical wall is built again just to give the silicone rubber a neat edge. The wall is thick and has to be pressed down hard so that it sticks to the wet plaster.
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Silicone applied to form the back part of the mould
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Wall removed and scraggy bits of rubber trimmed off
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Second half of plaster mother mould applied and shaped. The mould hasnt been separated yet and the original sculpture is still inside.
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Some wax patterns quickly cast. Im testing a few waxes with this one kindly supplied by FL
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Decided to do some experimentation with the sprueing and pouring. For the first one I am doing two together and having the metal enter from the top. The link between the two heads is just for support for more than anything else.
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Ceramic shell nearly finished. Will have the following layers. Slurry with sprinkling of molocite flour (200), then slurry between each of the folowing, 2 x medium grain molocite (30 - 80) then 2 x course grain molochite (16-30). Finish with slurry to stabilise loose grains
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pics of the casting to follow
mantrid
 
Posts: 45
Joined: Thu Jun 23, 2011 1:45 am

Re: Some More Mould Making, Ceramic Shell and Lost Wax

Postby mantrid » Sun Jun 26, 2011 3:02 am

The pour went well considering much of my tools and equipment were away from home. No grips for handling shell, no face shield, had to use some goggles, no big angle grinder so couldnt cut ingot to fit crucible so that it was positioned correctly in the kiln. Ended up putting the ingot in my square kiln and heating it direct until it got to the crumbly stage. I gave it a hard push with a rod and it broke, but not before the bottom of it started to melt and make a puddle on the kiln bottom.
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Most of the shell removed and I cant see any problems
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Desprued but shell still present, my sandblaster and compressor are away too. The black blob at the front is the remaining third of an ingot partially melted and holed where I was poking it with a rod to get it to break. The other bit is the part that melted away and flowed onto the kiln bottom
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What was left over from about 2/3rds of an ingot
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The crucible cooling down
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My humble set up. The kiln in the background and the gas cylinder furnace where I heated the shell. Normally I use them the other way around unless I can get them both in the kiln to save gas
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More to follow
mantrid
 
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Re: More Mould Making, Ceramic Shell & Lost Wax With Patinat

Postby mantrid » Sun Jun 26, 2011 3:05 am

Done two types of patina, liver of sulphur and liver of sulphur with cupric nitrate (green tinge) The green does not show well with the wax, I will apply it thicker. I also want to do the towel in a lighter colour so will mask of the woman with latex and sand blast the towel. I will try to create a lighter green or yellow on it

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mantrid
 
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Re: Some More Mould Making, Ceramic Shell and Lost Wax

Postby mantrid » Sun Jun 26, 2011 3:06 am

Re done both figures, couldnt achieve a red for the towel with the chemicals I have, tried rust but it didnt work. So the bronze coloured one is more or less the same (pics on my site). The one with a green tinge I layed the green on thick with liver of sulphur to try and create that ancient look of the Greek statues that have been pulled out of the sea etc. I didnt like it at first, thought it looked like something from 'the day of the dead', but its growing on me now.

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mantrid
 
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Re: Some More Mould Making, Ceramic Shell and Lost Wax

Postby C.R.Larkin » Sun Jun 26, 2011 7:35 pm

I'm doing my first patinas and so on, all I have is cupric and liver of Sulfur too. I also have a blue transparent dye-oxide put out by Sculpt Nouveau. I was given a packet of some samples when I ordered some things . Just mentioning it, because these dye oxides are great for "spot color." With a set of blue, red, and yellow, you'd have your primary colors and could make many more colors out of them. I used it with the Liver of Sulfur and it made a passable black color.

I was also wondering if you can burn out using a torch instead a kiln in that thin skin investment?

Are those muffin tins you put your ingot remains in? Will the bronze weld to the muffin tin metal?

Is that furnace a square made of fire brick? Can you make the plans available? I've looked into various types and think it would be neat to have something very light and portable for a furnace. Many people seem to use this wool stuff which I do not know much about. I thought you needed a strong metal container, like a big pot, that was filled with a cement like fire proof substance (cant think of the name right now).

One more thing, do you have problems with pinholes in the wax? I'd like to find some wax without this problem.
C.R.Larkin
 
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Location: Lincoln NE

Re: Some More Mould Making, Ceramic Shell and Lost Wax

Postby Giotto » Mon Jun 27, 2011 5:45 pm

Hi Mantrid,

The molds you make look great ! Really nice attention to detail. Thank you for posting them they are a great reference.

G
Giotto
 
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Re: Some More Mould Making, Ceramic Shell and Lost Wax

Postby mantrid » Tue Jun 28, 2011 10:06 am

C.R.Larkin wrote:
I was also wondering if you can burn out using a torch instead a kiln in that thin skin investment?

Are those muffin tins you put your ingot remains in? Will the bronze weld to the muffin tin metal?

Is that furnace a square made of fire brick? Can you make the plans available? I've looked into various types and think it would be neat to have something very light and portable for a furnace. Many people seem to use this wool stuff which I do not know much about. I thought you needed a strong metal container, like a big pot, that was filled with a cement like fire proof substance (cant think of the name right now).

One more thing, do you have problems with pinholes in the wax? I'd like to find some wax without this problem.


Yes a torch is fine, I use a torch for burn out with the opened fire brick kiln just for insulation so not too much heat is lost. However I use the closed kiln to preheat the shells before pouring the metal as its best if the shell is as hot as the metal at this stage.

Yes plain muffin tins, and no the bronze doesnt stick

Yes the furnace is just light weight fire bricks in a angle iron fram to hold them in place. Sorry no plans for the design, just made it up as I went along. Yes the wool is popular and has the advantage of lightness. I think it will breakdown though if not protected by some sort of hot face. Some furnaces use a castable refractory that you mix up like mortar, its longer lasting but heavy.

I dont have pin holes in my wax. I think this is cused by it being too hot or sometimes contamination can cause the wax to froth producing pin holes.
mantrid
 
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Re: Some More Mould Making, Ceramic Shell and Lost Wax

Postby mantrid » Tue Jun 28, 2011 10:06 am

Giotto wrote:Hi Mantrid,

The molds you make look great ! Really nice attention to detail. Thank you for posting them they are a great reference.

G


Thanks
mantrid
 
Posts: 45
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