Newbie needs technical help

[AlanMalawi]

Hi All,

I live in Malawi and I am primarily into Bonsai. Proper pots aren’t available locally so I am experimenting with making my own.

 

As such I am building a wood fired kiln (Electricity expensive and not reliable) (LPG Gas expensive)

 

So I need advice on the following 3 issues:

 

A Making High Temperature Mortar

I have a recipe :

            3 Parts Silica Sand *1

            1 Part Hydrated Lime

            1 Part Fireclay *2

            1 Part Portland cement

 

Q *1. Can I use pool filter sand?

Q*2 Can I use the raw clay I have dug up, sieved and dried and/or Clay based cat litter ?

 

B.     Making Fire bricks

Recipe 1 :

            2 Parts Fireclay *2

2 Part Sawdust

1 Part Wood Ash

 

Q*2 Can I use the raw clay I have dug up, sieved and dried and/or Clay based cat litter ?

 

Recxipe 2

            Silica Sand *1

            Sodium Silicate

 Q *1. Can I use pool filter sand?

 

C.     Homemade Glazes

 

Using the various ingredients listed below, what glazes can I make suitable for my raw clay and wood fired kiln?

 

In addition, I would love any advice from people who have faced similar issues and or suggestions as to my recipes etc.

Regards,

Alan

Available Ingredients / Chemicals

 

Laundry Bleach

Caustic Soda

Soda Ash

Sodium Carbonate Anhydrous

Magnesium Oxide

Copper II Oxide

Alumium Oxide

Ferrous Oxide

Sodium Meta Silicate

Sodium Silicate (Waterglass)

Gypsum Powder

Plaster of Paris

Hydrated Lime

Portland Cement

Silicon Sand (Pool Filter Sand)

 

Clay dug Locally

Cat Litter (Clay)

Wood Ash

 

[Min]

Hi Alan and welcome to the forum!

I'm going to move your thread over to the Equipment section as your kiln building questions would be better suited there. 

 

[AlanMalawi]

Thank you

[Kelly in AK]

Please find a copy of Pioneer Pottery by Michael Cardew if you haven't. His words could be gospel for you. 

A possible addition to your available materials: glass cullet? Glass, clay, and ash are a historic glaze. Caustic to apply and laborious to make, but essentially free to the potter. 

Edited July 27, 2023 by Kelly in AK

[AlanMalawi]

Thanks for the advice. Problem is there is chance of getting that book here in Malawi

Glass, clay, and ash are a historic glaze. does the kind of clay and or glass matter? Can I make my own glass cullet by v

crushing old bottles etc?

 

[PeterH]

4 hours ago, Kelly in AK said:

Please find a copy of Pioneer Pottery by Michael Cardew

+1  ... but my goto book source doesn't have anything cheap delivered to Malawi
https://tinyurl.com/ff2mm2th

[Kelly in AK]

Depending on any Internet restrictions in Malawi this might work, it’s how I read the book:

https://archive.org/details/pioneerpottery00card
 

l’m in over my head if I start talking what type of glass, what proportions, and the procedure for such a glaze. Stoneware potters of the southeast USA  were well know to use this type of glaze  a couple hundred years ago. 

[neilestrick]

For the mortar, you can just use fireclay and silica sand. No need for cement or anything like that. Sand should be pure silica sand, not play sand or sand that has other mineral impurities, because the sand could actually melt. Raw clay could work, as long as it can handle the temperatures the kiln will be firing to. Cat litter is bentonite, which wouldn't be good- very sticky, high shrinkage rate.

 

[AlanMalawi]

Hi, Thank you for response. My remaining question is - "What is definition of fireclay?"

I can't get any clays in the stores here. I have dug and processed my own clay here. 

How would I know if it is "fireclay" ?

 

\Regards

 

Alan

[Chilly]

On 7/27/2023 at 6:05 PM, Kelly in AK said:

Depending on any Internet restrictions in Malawi this might work, it’s how I read the book:

https://archive.org/details/pioneerpottery00card

Thank you for this link.  I started reading it late at night, and couldn't "put it down" as they say.  Don't know that I understand ( or will remember much, but so far it's fascinating.

[neilestrick]

On 7/30/2023 at 11:41 PM, AlanMalawi said:

My remaining question is - "What is definition of fireclay?"

See HERE. For your mortar, you need a clay that can repeatedly handle the temps of your kiln. So if you're going to fire to 1300C, you want a clay that can go at least a couple hundred degrees higher than that. You don't want a lot of shrinkage in the mortar, although the silica sand will help with that. Of course, we make do with what we have. So if you only have one option, then use it, mixed about 50/50 with silica sand, and keep the mortar joints very thin. If you have good bricks, mix it up as a slip and just dip the edge of the brick in it. If you have uneven bricks then you'll have to go thicker with the mortar to fill the voids.