# Crucible: Step by step. Part 1 of many



## DONNZ (Feb 21, 2012)

*Hold posting, comments and questions till the end.*
This is part 1. Limited to 5 photo's per post. This will take a few days.

Pic's the best I can do, I'm video illiterate and terrible writer.

Most of this you may already know. Some have never worked with clay. 
Basically sharing what I've learned and how I'm doing it. 
Mixing clay and fire brick I've never done before, only clay, long, lone time ago. 
I enjoy a challenge.

Will be making several more crucibles and dishes. Looking for another dish shape.
Will make a couple of dish with sifted brick and see if borax fills and smooth.
All here were made fire brick powder and clay.

Of course proof needed. Dry then fire in a kiln. Know two kiln owners.

Enjoy.


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## DONNZ (Feb 21, 2012)

Next 5:


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## DONNZ (Feb 21, 2012)

Next 5


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## DONNZ (Feb 21, 2012)

Next:


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## Palladium (Feb 21, 2012)

Thanks !!!


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## DONNZ (Feb 21, 2012)

Next:
4 more post and you will have everything you didn't want to know about this subject.


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## DONNZ (Feb 22, 2012)

3 more to go:


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## DONNZ (Feb 22, 2012)

2 more to go:


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## DONNZ (Feb 22, 2012)

At last:
If I had a starting point it would be a dish. Easy to work on and tough me how to deal with the clay, fire brick combination.


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## DONNZ (Feb 22, 2012)

One good one that I overlooked. 

All this was to serve as a basic guide, nothing more. 

Like I said, need to fire.


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## samuel-a (Feb 23, 2012)

DONNZ

Have you fried them yet?
Have you tested one with our working temp' ?


You have done real nice, but in my opinion they will not hold the heat and crack.
A friend of mine made some crucibles for me on a Potter's wheel, they didn't survived the torch.

As far as i know, the clay should be the same thickness through the entire walls and bottom. Also, the clay should be packed tightly while forming into shape.
Then drying and frying.

Keep up the good work !


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## DONNZ (Feb 24, 2012)

samuel-a

Not fired. In various stages of dry. High humidity slowing the process.

Don't know what happen to your crucibles, can only ask questions.

What mix did your friend use. A 40/60 mix of clay and fire brick.
Did you heat the crucible slowly with the torch.

I wouldn't use a crucible in this manner, that would be a job for a melting dish.

My only reference is that video on Ytube where a crucible was formed around the end of garden tool handle and how to make a mold that was posted on the forum. But we didn't see it in action, did it hold up when used?


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## qst42know (Feb 25, 2012)

I think the author melted aluminum in the crucible they made.


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## DONNZ (Feb 27, 2012)

Still playing around with a dish. Using sifted fire brick, not powder. I want to eliminate that step.

Shows promise. Maybe a bigger cookie cutter.


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## DONNZ (Feb 28, 2012)

Turned it out this morning, cleaned the edge up a bit and brushed it off.

A 99% chance it will fail. This is only a demo. Failure will be due to: Clay is to wet.


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## lazersteve (Feb 28, 2012)

Donnz,

Nice job on the process.

When I work with Kast-O-Lite 30 refractory the manufacturers instructions for drying are :

1) Air dry 16-48 hours at room temp (15-21C) keeping surface damp.
2) Ambient to 120ºC increased @ 55ºC / hour
3) Hold at 120ºC for 30 mins per 25mm thickness
4) 120ºC to 250ºC increased @ 55ºC / hour
5) Hold at 250ºC for 30 mins per 25mm thickness

Maybe this will help.

Steve


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## DONNZ (Feb 28, 2012)

Process gone as far as I can take it. It's simple, no mold melting dish. 

Air dried all day.
Bagged it before bed. 
Will dry if the rain goes away.
Then to the oven. Figure two day. Start low and go to 350% a couple of times to drive out the last bit of moisture. 
Fine a kiln. First one way to big. Overkill. Some of my friends are warped.
Dude, I'm not melting an engine block.


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## DONNZ (Feb 28, 2012)

PVC, sturdy, pull rubber band up or pull down on clear here and there to get the shape. 
This one 4" inside. I guess it can be better.


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## DONNZ (Feb 29, 2012)

Can't believe I didn't pick up and use the PVC and play with it before now, just got lucky.
It's so much easier to work with. 
But the depth of the dish is not adjustable. 

Rolling the rubber band down the PVC, pulling the clear up over the band and moving it all up to the top lowering it deeper into the PVC gave little change in depth.

I would like some depth in the dish. 

I got lucky a second time.

I picked up my cutter, placing small end up (just by chance) picking up the PVC with clay at the bottom and placed over and down into the cutter. Adjusted the clear. 

The cutter is forcing the walls in, giving the dish depth.

I can go bigger with the cutter and make any size dish I wish.
But I have something else in mind.
If I can lower it into something smaller like that measuring cup (clear one) from a liquid detergent bottle I will have solved another problem:

Make a crucible.

That would be cool.

PVC: 4" inside. 2½ Deep.
Cookie Cutter: about 1½ Deep with the lip trimmed off. Can use either end for cutting. I'm using the big end as the cutter. 
Clay rolled ¼" thick.


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## butcher (Mar 7, 2012)

Here is an idea; I hope I can explain it so it is understandable.

What if you took a steel pan, poured concrete in it, sunk the plastic cup (HDPE) in the cement; let it dry, to make the bottom mold.

Then took a second plastic cup (HDPE), and poured cement in this second cup, inserting a steel plug into it, for the top mold.

Then formed your refractory clay into the bottom lubed mold a little thicker than the cupel would be, then inserted the top lubed mold and in a shop press, squeezed out the excess clay, between the two molds.

Some other material may be needed to replace the cement for strength.

Does this Idea make any sense?


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## DONNZ (Mar 7, 2012)

Can't see why that wouldn't work.

Trying one more experiment using the clear measuring cup. Not liking the first one, to many wrinkles on the out side of the crucible. I think this has a solution. Main thing is keeping it simple.
I need to stop and get some fired. May have a solution for that also. 



butcher said:


> Here is an idea; I hope I can explain it so it is understandable.
> 
> What if you took a steel pan, poured concrete in it, sunk the plastic cup (HDPE) in the cement; let it dry, to make the bottom mold.
> 
> ...


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## jmdlcar (May 25, 2012)

Are this kind worth getting LECO Hi Temp (silica) Crucibles?


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## DONNZ (May 26, 2012)

I have several and they hold up well. Operations at temperatures up to 3200°F (1760°C)

Never see bigger than 1od and boats for sale. 

http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=140759494545+&item=140759494545&vectorid=229466

They do make other sizes: under Products/Spec

http://www.leco.com/products/ceramics/ceramics.html


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## Jaffajake (Jul 12, 2012)

Hey, first post on here. Perhaps you could get a large resealable freezer bag filled with those silica gell beads that you get from new shoes to dry the crucibles out before firing. That's called a dessicator bag if you didn't know, which is designed to remove water from hygroscopic materials. There's a good tutorial on YouTube by NurdRage on dessicator bags. Hope it helps, 
Jake.


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## Geo (Jul 12, 2012)

thumbs up for reviving a thread. a good material for soaking up a lot of moisture is the material in disposable baby diapers. that stuff will absorb many times its weight in water.


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## goldsilverpro (Jul 12, 2012)

Geo said:


> thumbs up for reviving a thread. a good material for soaking up a lot of moisture is the material in disposable baby diapers. that stuff will absorb many times its weight in water.



As far as the revival of this subject, I agree. I think DONNZ has done a great job on this. It's an interesting subject. Something I've always wanted to mess with but it always took the back burner. My particular interest was in making cupels. All the old time assayers made their own.


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## DONNZ (Jul 13, 2012)

More on the subject to come. A tad busy moving friends that lost their art compound. New owner wants it all. 7 spaces and I know 4 of them. Whole lot of moving going on.

Pic of work in progress. Not a good pic, a rush job. Bag and let dry. Drying to fast can cause cracks.

The kinds words of support inspires. A Big Thank you.


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## butcher (Jul 13, 2012)

Those are looking professional, nice job, now I cannot wait to see the picture with gold melted in the bottom of one.


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## Jaffajake (Jul 16, 2012)

Those are looking good! I also can't wait to see them in use. I use the silica gel sachets in my bags because I don't want my PM clays to crack when drying. I found out that using the fibres from sanitary towels (easier to steal from girlfriend(readily available)) would dry out the clay too quickly, so another method was needed. The silica gel beads work for me, so I hope they work for you too


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## DONNZ (Aug 8, 2012)

DONNZ update:

I owe updates on my work but had putor problems. Major system crash and lost the connection to my HD. My back-up program is running the putor for the moment.
My IP contract ran out last month.
Did all that in one week. Boooooo. 

My system is iffy and time on this connection is limited, (don't ask how I'm doing this) must be brief. 

I'll be back.


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