I have been asked to make a brick....

from a clay seam that was discovered in very the Far North around 1911.
Pine Murray remembers that this is very strong clay and the water content is very low.
This clay is grey and when fired it turns a pale yellow with terracotta flecks.
He would like some of it made into a brick so that people can see the possibilities it holds.
He is bringing me a bucket of this clay to experiment with.
I have never made a brick before ......... any help would be appreciated

Good challenge, Ev. What kind of brick are you wanting to make? Sandstock or slop-moulded? And if you're just making one are you going to build a mould for it? And what sort of frog?

http://www.shol.com/agita/thespiel.htm seems to cover the basics.

A good starting point could be Edward Dobson's book "A Rudimentary Treatise On The Manufacture Of Bricks And Tiles: Containing An Outline Of The Principles Of Brickmaking" which you should be able to get from a library and which has also been digitized by Google books.

Thanks Tony, thought you would be able to help me out
I thought of making a solid brick shape with the clay as it is -
then poking maybe two holes through the middle of the length of it,
as any clay thicker than around 3/4 of an inch thick explodes when fired
at our firing cycles.
I will surf the net about it and go to the library too though.

A bag of this clay arrived today.... it's rather hard so I have sloshed some water over it to soften it.
It looks just the same as the New Lynn Trench clay!
I think a brick is the perfect thing to make with it

I spoke with the supplier of the clay today..... a Kaumatua from Te Hapua in the far north.
Ngati Kuri is the Iwi ......though they were here before the great canoes arrived ... ever so interesting.
The clay has been tested before - it was sent to China and they said it was the best clay to work with to make plates.
A brick has been made before and sent to the [?]University and tested - the results were that it was light but strong and only contained 2% water, whereas normal bricks hold 3% water. This brick has been misplaced.
The colour should turn out to be a golden colour with red flecks.
They had to dig a metre down with a post hole borer to get the clay.
They believe this clay is very special clay.
Taihoa ..... take your time he said..... ok

Hi Ev

There are two books I know of that talk about brick making, the first is the Barry Brickell dictionary p29-32, it even has drawings. The other book I believe is the one by Cardew, Pioneer Pottery p261-268

I have a plaster brick mould I made some years ago. It is the same size as a good sized solid fire brick.

You might like to try adding saw dust to the brick mix, this will give the brick better insulating porperties, Driving Creek Railway bricks have lots of grog in them.

Thanks Tim ..... I will check out those books.
I will try with and without grog ..... don't have any sawdust left as used it all doing raku.

This is awesome clay!!!!!!
One of the nicest that I've ever handled ....
as velvety as...... dare I say it PORCELAIN !!!!!!
It is an off white colour with threads of orange/iron through it.
When wedged up it evens out to a glorious golden colour !!!!
I've spent a bit of time researching Te Hapua -
it's on the Parengarenga Harbour .... very close to Matauri Bay!
Matauri Bay is famous for it's halloysite clay pits..... Crown Lynn used this clay.
That clay is now exported all over the world - ever since Crown Lynn closed down.
It is the finest white clay [Aluminium Silicate Hydroxide] and is highly sought after by the big ceramic makers of fine china..... including Noritake.
Also Te Hapua was where the Maori Land March left from for Wellington in Sept 1975.....
Oh and politician Matiu [Matt] Rata was born there in 1934.
Pineaha rang last night to see how things were going......
so I got into it today ... clay is worked up...
I have a mitre board that should work
This is exciting!!

let see some pics

First effort failed miserably.....
when I pushed in an item to remove clay from the brick insides...... the outside split under the pressure.
Back to the drawing board...... and puts another thinking cap on.
Photo will be available when success has been achieved
This clay is too good to make bricks with!!!!!!!!!!

Success!!!! Just the clay ... no additives... next one will have plenty of grog added.
And what did I use to make the holes? A pencil and a kebab skewer lmaooooooo





The first photo shows the true colour of the clay.

What's its dimentions?

It's small ...... 16.5 x 6 cms ..... wet.

What size is your brick mould?

Its 22x12x10.5 same size as the fire brick I used as a model

Firebricks are bigger than ordinary bricks.... @ 22.8 x 11.4 x 7.6 as per Barry Brickell
I haven't looked for ordinary brick measurements

Just finished one that has grog in it 22 x 9 x 7 cms...... getting there but almost out of clay!

The brick with grog in it had a large crack in the middle of one side this morning
I worked the clay back ..... but have my doubts that it will not return!

After nearly 40 years of working with clay .... I haven't had much experience with 'dug clay'
until recently.... so it's all a big learning curve for me! I'm really keen to learn more about it and I'm enjoying Barry Brickell's knowledge about this subject from his 'A Potters Dictionary'.

No doubt some of Barry's bricks had cracks in them too.

The crack is back ..... bigger than before

The smaller brick is in the kiln being fired to 1130'.
Pineaha rang this morning to see how things were going,
and said he had another bag of this clay for me.
I asked if where it came from was close to the Matauri Bay clay pits.
He said that was a long way away....... so now I'm a mite confused

The brick is fired....
The spit test shows that the clay hasn't quite vitrified.....
so it will be fired again to 1180' when there is a firing at that temperature.
The colour is still very yellow...... but it's not a real earthenware temp clay...?
Must take a pic to show what I mean ..... too busy right now though .... Whitiangi here I come

Pic as promised...

To continue the story...

I did the age old test of making a coil and trying to tie a knot in it to show plasticity....
alas, I could not even slightly bend the coil without the clay breaking!
This told me that the clay was very 'short'.

I pressed some of the clay into a Manaia mould and this proved to be very successful.
Then I tried using it on the wheel ....
WoW!!! the clay felt like silk running through my fingers!
It was the most beautiful clay to throw .... it made me euphoric!
I made 4 beakers. Two of these had splits in their bases when they had dried.....?

I put a honey glaze on the Manaia and a turquoise green glaze on the beakers.
These along with the brick were then fired to 1180c.

More to come....

Back again....

Honey glaze came out very dark - turquoise glaze was a murky green!
This tells me that the iron content in the clay is quite high .... my guesstimate is between 6 -8%




The brick now measures 13.8cm x 5cm
so going by my calculations the shrinkage rate at 1180c is around 16%
this is on the high side as most clays that I use have a shrinkage rate of around 12%.
I'm just writing a report and then my job is done