Cob:smashing Brick

[Amanda Peck]

I've been adding color via clay to my chinking mix (which has been pretty 
variable in composition, but something on the order of lots of sand, fair 
amount of sawdust, a little lime putty, a little mortar, a little clay).  
Especially since I switched from pine to hickory sawdust, the color is 
pretty nice when I first mix it, but soon fades to a just off-white, maybe a 
little more color with the--by now nicely aged--hickory sawdust.

Nice to be told that the concrete colors intended for a high-lime 
environment work for higher concentrations of lime too.  I didn't really 
think of it, slapped myself upside the head when I read what Charmaine 
wrote.  Those colors are POWERFUL, though--a couple of tablespoons will go a 
long way.

............
Charmaine wrote:
using human labor to smash a brick that costs 20 cents ( or even free) to 
get the red color  could more easily be served by buying a sack of red 
pigment for ~$3.00 ( these are meant for cement base mixes and can usually 
be used for lime too.)

also broken bricks can be rubbed together to get the red powder, but adding 
it to a plaster will damp down the color to pink. I have collected broken 
red bricks and the powder resulting from sitting in a pile, and it makes a 
nice pozzolanic additive to my plasters.  any fired brick that is ground up 
is a binding agent in a lime plaster, making it harder.  but this free brick 
dust was just scooped up into a pail, no smashing.

red clay, added to plaster can also give a red color, but if it is a lime 
plaster the color will lighten due to the lime, to a nice pale orange or 
paler red/pink again.

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