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Peter Angel

Making terra cotta bricks

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Dear all, i want to carve some bricks while they are soft, then sun dry them,  then fire them extra slowly,  then carve the detail into the well fired brick.

I've researched this and all the instructions tell me to dig up natural clay. I can't do this as i live in the city and i don't have land to dig.

Would it work if i buy some terra cotta powder and silica sand, add water, and mix it thoroughly? 

Regards, Pete

Edited by Peter Angel
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I would use bagged terracotta sculptural clay which should include grog.

I would also make your bricks a little thinner than conventional store bought bricks.  Commercial bricks are made and fired a little differently, which means they can get away with things we can't.  Have a look at African fired bricks or Roman brickwork for ideas about how to make them in a more potter friendly way.

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Yes. You might look at some old brick making techniques to give you some ideas. My brother makes wooden molds for custom shapes of bricks, fills them with clay, then wires the excess clay from the top of the mold. The clay he uses is Redart for the color, sand as an aggregate/adds a coarse texture, and some ball clay for plasticity. I fire them to cone 04 and he uses them like regular bricks. The bricks when installed act like a crown molding/baseboard trim. It’s inefficient but it makes his home unique. Adding some type of coarse material will improve the drying properties of clay. Also, I’m not sure why you would add further detail after the clay is fired, it is easier to work with when plastic and holds detail very well.

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On November 5, 2017 at 7:13 PM, glazenerd said:

* 5-15% grog can be added to either recipe

here is a recipe for standard red brick (cone 04)

50% silica , 25% Hawthorne Bond, 25% a Red Art

and here is a recipe for (cone 04) red body clay

50% Red Art, 15% Hawthorne Bond, 25% OM4, 5% silica! and 10% talc. ( from Alfred U)

 

 

Nerd

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These are from my Architectural ceramics Handouts when I taught Architectural ceramics workshops.  

Marcia

Chip Clauson's Freeze Proof Terra Cotta

                                     Batch        %

Hawthorne Fire Clay      20       9

C and C Ball                    50        21

Red Art                            100      43

Talc                                   15         6

Muddox Grog                   50        21

.5 Barium Carbonate 

Alfred's Terra Cotta

Ocmulgee      25%

Red Art         25

PBX    Fire Clay  20

Calvert               10

Neph. Syen.        5

Talc                     5

Silica                   10

for handbuilding add 10% fine grog

   Terra Cotta    ^06 to ^02

Red Art                100

Gold Art                 40

Ocmulgee               40

Talc                        17

Sand                       12

200 pound + batch  dissolve 3/4 cup of barium carb. on water and add to batch

Carrie Esser Red Sculpture clay  ^04

Goldart           15

Red Art           40

Hawthorne      20

Talc                    5

Neph. Syen.       5

Wollastonite     15

Grog                  20

Barium Carb      1  dissolve first

 

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I assume you want to make bricks like this one that a fellow potter made  that says Blue Lake block.

This was fired to cone 10 very slowly

Its a bit more durable than terra cotta  ones

I think what Tyler says-add plenty of course grog at least 20%. Fire very slowly.

The one here is standard size when fired.

The one below it is from Nelson New Zealand-Hand carried it home in the 90s.Xray folks all wanted to see it at every airport.

IMG_3667.jpg

Edited by Mark C.

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Chris Berti's artist statement,images carved from vintage ceramic brick and drainage pipe" It must be easier to sculpt them out of clay, unless of course you are a stonemason? The lady with the melanoma's looks like you could add a lot of combustable material to the super groggy clay and have it burn out leaving those deep pits and craters. Looks like the female torso is  "Volcanic scoria basalt sculpture" by Jon Dixon, from a google search.

Edited by Min
clarity

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9 hours ago, Peter Angel said:

These aren't mine!

I think these have been carved after firing.

This is the type of thing I want to make. Pete

 

There's a reason these are carved out of old brick - old brick was often much softer. I can remember carving a headstone from an old (c.1850) soft house-brick for my pet mouse when he died, with little more than a bent nail and a blunt screwdriver (I was young, and we were poor). I can also remember how easy it was (allegedly) to carve initials and the like into the walls of the school-yard, also made with soft brick (c. 1900), with nothing more than a piece of fencing wire.

So, with proper tools, carving a soft-fired brick would be dead easy.

You might like to consider the possibility of mixing up a paper-clay. The advantage here is that you can rough sculpt your piece, sinter fire it, refine the details with further carving, as delicate as you like, and then hard-fire it. (Sinter firing involves a low firing, way below vitrification temperature, but which gives a wonderfully carve-able body.)  Rosanne Gault's Ceramics Handbook 'Paper Clay' gives plenty of examples.

You might also like to look at 'Architectural Ceramics for the Studio Potter: Designing, Building, Installing' by Peter King, where various recipes are given for bodies which might suit your purpose, including a paper clay. (The page review of this book in Google Books just happens to cover that page...)

 

Edited by Sputty
Inclusion of deathly important detail, without which I would have failed in my enterprise.

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Hello all,

I have made a brick mould.

It's made of wood and I keep it wet before adding my clay.

I'm using an ancient roman brick recipe of 60% terracotta powder and 40% fine river sand...(river sand has minimal shell in the sand).

I works really well and the brick mold lifts straight up leaving a perfectly formed brick.  

Here is a you tube video that shows the concept. My mold is less wet than his. I let it drain for a minute. It's closer to damp than wet.

 

The big problem I am having is the wet clay brick sticks to the bottom wooden board.  Even after 3 days it's still stuck.

Any solutions?

Pete

 

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You have options-you could

Talc powder the board first .

Cover the board with piece of canvas and have a few for when they get to wet.

Use cement board (tile setting substrate-like hardiboard) on bottom board

move to the desert. Barstow is cheap and hot

I can add some other but this is a start

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57 minutes ago, Peter Angel said:

The big problem I am having is the wet clay brick sticks to the bottom wooden board.  Even after 3 days it's still stuck.

Any solutions?

 

Wire them off with a heavy cut off wire after they have set up a bit.

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42 minutes ago, Peter Angel said:

Thanks for your help.

Mark C, if I use dry canvas, will the bottom of the brick pick up the texture weave of the canvas ?

Pete

 

Yes -but you can buy slab Matt bless from the manufacture and they leave no texture.

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