[Cob] Waterproofing Clay

[Stephen Karrington]

Hello,

I am ready to put on the finish coat on my mud bar. This is a rounded
bar that will be in a cafe in Thailand.

The local guys brought in colored concrete tile grout. But it doesn't
sound too good to me to use concrete on a clay bar.

I need to waterproof to some extent the top of the bar so if someone
spills something it won't seep into the clay and discolor it. I also
want it as smooth as can be.

The textures we did on the walls and other places in the cafe are
fairly grainy/sandy. I prefer a smooth finish on the top of the bar
though.

I prefer to go natural and non-toxic for this finish. But if I have no choice then I
will have to use some toxic sealer that does the job.

Locally I can get red sand, some white sand, cement. What I couldn't
get while doing this job which made the wall textures very time
consuming is pre-colored 50 lb colored/clay products. That stuff
doesn't seem to exist here. So we had to mix everything by hand and
each batch can be different.

Any suggestions would be greatly appreciated. Thanks.

Stephen