[Cob] interior finish - limewash

[Hendrik Jeremy Mentz]

I experienced the same problem and received the following advice from Tom O'
Connor from Midas (Earthcote) paints in Cape Town. He said that what most of
us (including me) don't realise is that limewash needs time to cure. He
therefore suggested that after we have prepared our wall (i.e. scraped off
all the old paint, etc.) we must wet it and then apply our first coat of
limewash. Once our limewash is touch-dry, wet it down with a fine mist spray
every day for about three days until the limewash is properly cured.
Thereafter wet the wall down again and apply a second coat of limewash and
repeat the regime (i.e. once touch dry: mist spray every day for about three
days). Tom says that we'll then get a hard cure and shouldn't rub off.

I checked with Tom to confirm that he didn't mind my quoting him. I share
his reply in full, because it is also helpful:

"I have no problem with you sending the mail, however reading the initial
query, I would like to comment. The formulation of limewash generally
includes rock salt but I cannot comment on the situation where this is not
included. The formulation of old, was normally as follows: unslaked lime,
tallow (animal fat) and rock salt. The lime was "cooked" prior to additions
of tallow and salt.

Regardless of the above formulations and proper curing, limewash will never
offer a "washable" finish. It is absorbent in nature and course textured
therefore attempting to wipe off dirty hand marks or other surface
contamination is not a feasible option. We have a product called Limecoat
which is a blend of hydrated lime and acrylic. This would offer a more
suitable finish although it does not have the texture of limewash, it does
have a mottled finish."

Hendrik

-----Original Message-----
From: coblist-bounces at deatech.com [mailto:coblist-bounces at deatech.com]On
Behalf Of pirate king
Sent: 19 June 2007 11:25
To: coblist at deatech.com
Subject: [Cob] interior finish - limewash


Hi,

Thanks everyone for your suggestions about the exterior flooring
problem. I plan to experiment with hydrate lime and see how it goes. We
can't get psyllium over here.

Another question! We are finishing the interior of our cabin with
limewash (approx 4 lime putty - 1 casein from off milk - 5 water) over a
lime plaster. Trouble is, it doesn't seem like a very practical finish -
it dusts (a bit) and it's impossible to clean - muddy fingerprints etc.
just smear when you try and rub them off. Is this some problem with our
mix or our application method - maybe the limewash hasn't set properly?

Thanks!

Robert
www.lesspress.com

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