Not brick making but pottery/glazing... which has some of the same colour 
effects (depending on if the bricks are fired under oxidizing or reducing 
conditions... the colours I'm listing are for oxidizing conditions. I am not 
sure of reducing condition colours - I do not do enough reduction firings to 
know what colours the various oxides give.

Cobat oxide - blue
Iron oxide - red
Copper oxide - green
Manganese oxide - brown

Granted these colours are based on the fact that the clay body you are using 
for the bricks is white or grey and not black or red.
Red and some of the black clays fire to a red colour so mixing oxides with them 
just tends to give muddy versions of the colour of the oxides.

Different combinations of minerals will give you different colours due to 
chemical reactions... so it doesn't work like a painting where you can mix 
colours - sure you can mix the colours but blue (cobalt) and red (iron) do not 
give purple... it acutally gives a sort of goldish colour or a muddy brown - 
depending on proportions of the mix.

Often time the colour of bricks has to do with the local clay they made the 
brick from - typically brick is made from the cheapest local clay deposit. So 
the colour is more a consequence of which of the brick works you get the brick 
from.

The exception to this is the brick that is made into high temperature brick - 
where they take high quality clays and have specific recipes that allow the 
brick to survive high temps or exotic chemical conditions.
Fire brick is pretty much a uniform yellow/beige colour. 

-Sue

--- On Tue, 11/2/10, nigel mccarty-eigenmann <[email protected]> wrote:

> From: nigel mccarty-eigenmann <[email protected]>
> Subject: [gurps] A question about Bricks
> To: "Gurps" <[email protected]>
> Received: Tuesday, November 2, 2010, 6:22 AM
> Dear Groupmind, 
> 
> Anyone know about brickmaking?
> 
> What mineral contents would make a brick come out of the
> oven blue, green
> and black?
> 
> 
> McE
> 
> 
> _______________________________________________
> GurpsNet-L mailing list <[email protected]>
> http://mail.sjgames.com/mailman/listinfo/gurpsnet-l
> 
_______________________________________________
GurpsNet-L mailing list <[email protected]>
http://mail.sjgames.com/mailman/listinfo/gurpsnet-l

Reply via email to