Porcelain Slip Recipe

[Celia UK]

I have been given a 25kg bag of powdered porcelain. If I want to use this to make casting slip, what other ingredients would I need and in what proportion? Also, could I use it for throwing - if so, same question, what else would I need to add?

 

I hate to waste a 'freebie' so would welcome any helpful comments.

[neilestrick]

http://www.lagunaclay.com/support/art-of-slipmaking.php

 

To mix clay for throwing without using a mixer or pug mill, add water until it forms a thick slip. Mix well to get all the lumps out. Lay it out on a plaster slab or concrete floor and let it dry to a workable consistency. Wedge and throw.

[Biglou13]

what does bag say on it, is it a clay mix or kaolin?  need more information.

 

grolleg, tile 6, epk, velvacast, helmer, kaopaque, new zeland, glomax, pioneer, d-10, remblend, trevisco....

if its just a bag a kaolin most likely not going to make a clay body out of it alone.  epk is cone 31

 

but like neil said ..... a paint mixer and the slurry technique will get you there.

[Celia UK]

Thanks Neil - I can easily add water and put out on a batt etc. I had found the Laguna info you linked to, thank you. My issue was that my bag did not identify itself as any of the listed ingredients - hence my query.

 

In reply to Biglou - the bag just has 'porcelain' on the outside as far as I can remember. (I'm away from home until next week, so would have to check for sure) I'll post again if I get any more info.

 

Celia

[Celia UK]

I've managed to trace this porcelain back to Potterycrafts (UK) and they have told me that it's the equivalent of their David Leach Porcelain Plastic clay, normally used to produce casting slip with the addition of sodium silicate. Does thus sound as if it could also mix up to become suitable for throwing?

[Mark C.]

Casting slips and throwing clays are way different animals. 

If its casting slip then throwing is not what it will do well at all.

My answer is no its not suitable for throwing.But you could try and let us know as you are in new territory of the unknown.

Mark

[oldlady]

are you talking to a technician who actually worked with this stuff or someone hired in the last 10 years who is repeating what he thinks he heard?  as far as i know, and that ain't far, DAVID leach worked on the wheel.  i would be surprised to know that he ever used a casting slip.  talk to john leach in muchelney, somerset.

[Celia UK]

Right, so I've looked a bit deeper and this porcelain is listed in the Clay>Bone China/Porcelains section of the Potterycrafts' product list. It is named as 'Dl translucent porcelain' and the product info says it is suitable for throwing, casting, machine making, flower making & fine sculpture. So I guess I've now answered my own question!

The technician at Potterycrafts is definitely not a newbie - he's been around along time. His reply to my query about how to use this for casting included - "the recipe given in my very old catalogue is to 50kgs/110 lbs of clay add 60 fluid ozs (2.11 litres) of P3344 Sodium Silicate ( 140 tw) and 22.8 litres/39.9 pints of water."

 

So with this and Neil's advice on mixing with water to produce a throwing porcelain - I have both options available to me! Given the challenges of throwing porcelain, is there anything else I might need to add to help with the throwing properties, or does it sound as if this product would contain the necessary - as it says it's suitable for throwing?

[oldlady]

ah, success at last!  getting the info, i mean.

 

do not know the answer to your technical question but i would recommend using distilled water.  with so much invested in this project, why take a chance on something being in your water that will affect the outcome?  

 

good luck, let us see the results.

[Biglou13]

are you making a casting slip

 

or clay body???

[Celia UK]

Thanks for that Old Lady - distilled water it is!

 

Biglou - I thought I might try both - sometime! My final question referred to mixing it for throwing, the maufacturers have advised me regarding a recipe for casting slip.

 

Thanks for all your replies - it's great to be able to draw on everyone's expertise.

[Biglou13]

What do the mfgr's say about throwing clay body. The porcelain casting slip recipes I've seen have no bentonite or the like. Text says avoid the same. Bentonite or the like is necessary for porcelain clay body plasticity, when throwing.. If you have access to mfgr I'd ask them. In addition to Neil's technique Instead of drying clay on plaster slab, a pillow case in flower pot works. (Just made 80 pounds of clay with pillow case technique.

[Celia UK]

Thanks Biglou - I've emailed the technician again for further clarification & will post again when I hear back.

[Celia UK]

The technician has said that he believes the powder is just dried clay and will therefore only need the addition of water - about 20% - to make a throwing clay. I guess I'll just have to bite the bullet and go for it! Thanks for everyone's responses.

[Biglou13]

Really! "Dried clay". Could he be any more vague.

 

Fire clay, ball clay, kaolin/china clay,red clay, shale clay, bentonite,stoneware clay, ...........all available in dry state, none exclusively make a throwable porcelain clay.

 

If he meant it's just dry porcelain clay, then it's a different and possibly problematic issue. I'm venturing to say all porcelain bodies made for throwing/ hand building are not just kaolin, or china clay. While porcelain alone will vitrify at very very high temps. You will need multiple ingredients to make a "throwing" clay. So I'm highly suspect of the statement "it's just dried clay".

 

20% water weight is acceptable, my recent home made clays ended up with closer to 30% water weight. Using the technique as Neil stated earlier will need a higher percentage of water as you are making a slurry, then drying to clay.

 

I hope you enjoy making clay as much as I do. As always testing is king. What Im trying to say with out being discouraging is that your basically trying to make a clay with unknown ingredients, and expecting a useable product. It's like throwing un known white flour like material in a bowl with water and expecting scones. Don't be disappointed if first attempt is a failure. But through a series of trial and error cycles I'm sure you will be able to make a clay from your bag. But then again it may work first time.

 

Making clay with slurry method is both time consuming and messy. I'd suggest you start your clay making experience with a tested formula/recipe. I still believe there is value in tinkering and figuring things out. However, For first time making clay it will be more rewarding if you end up with a useable product. I'd even be willing to weigh out and send you one of my porcelaineous dry clays , for the cost of shipping.

[Celia UK]

Thanks again Biglou. I must say that making clay is not something on my creative agenda, it was simply that I'd been given an unwanted bag of porcelain and wanted to make use of it. I now know what to try, but haven't had time to get on to that yet. Still struggling to get some decent glazes to enhance my work. I WILL post again once I've tried the porcelain!

[akasha2683]

Hi! I love making porcelain sculptures and im from Colombia( south america). I would like to ask you about the porcelain powder(premixed),im always buy the porcelain slip but due to the shipping cost i think its better for me to buy porcelain in powder. Im never do this so i dont know where i can buy it in this form and the most important how can i reconstitute it for using to cast molds.
Please it wou be great if you can inform me about the posibles types and the sites for buy it.

 

[PeterH]

The bag should have an identification number on it (perhaps a P followed by 4 digits)

which might help identify quite what you have got.

 

Although Potterycrafts sell quite a few moist porcelain, they don't sell many powdered ones.

http://www.potterycrafts.co.uk/Products/bone-chinaporcelains

http://www.potterycrafts.co.uk/Products/powdered-clays

 

Indeed the only powdered porcelain one in their current calalogue looks like the one I have used in the past,

which already contains defloculant.