Building with earth - Gernot MINKE (1)

12.1
12.1 µ-values of
water-repellent loam
plasters and s d -values
of coatings
Water-repellents loam plasters
Clayey plaster (clay = 6%, silt = 6%, sand = 88%)
nontreated
Wacker, STEINFESTIGER H
Herbol, FASSADENIMPRÄGN. HYDROPHOB
Indula, HYDROPHOBIN
Wacker, BS 15
Metroark, SYLTRIT 1772
Bayer, BAYSILONE IMPRÄGN.-EMULSION
Silty plaster (clay = 3%, silt = 18%, sand = 79%)
nontreated
Wacker, STEINFESTIGER H
Herbol, FASSADENIMPRÄGN. HYDROPHOB
Indula, HYDROPHOBIN
Wacker, BS 15
Metroark, SYLTRIT 1772
Bayer, BAYSILONE IMPRÄGN.-EMULSION
Lime-casein wash
Lime washes are much more wipe-resistant
and durable if whey, fat-free white cheese
(quark) or casein powder is added. Quark
is obtained when rennet from young cows
is added to skimmed milk. This cheese contains
11% casein. Lime, together with casein,
forms a chemical waterproofing agent
called lime albuminate. Today, the use of
cheese is the best solution for lime-casein
washes. In traditional lime-casein washes,
whey or sometimes skimmed milk was
used instead of cheese.
Mixtures containing 1 part fat-free cheese,
1 to 3 parts hydraulic lime and 1.5 to 2.5
parts water proved effective. Small amounts
of double-boiled linseed oil (not more than
4% of the amount of cheese) increase wipe
resistance but reduce the workability of the
wash. To get an even emulsion, it has to be
well-mixed and stirred from time to time
(sometimes every five minutes).
µ-value
An even stronger and more wipe-resistant
paint is obtained by mixing 1 part hydraulic
lime with 5 parts fat-free cheese and 5 parts
loam.
In bathrooms and kitchens, where greater
dry and wet wipe resistance is required,
the following procedure is recommended:
1 part hydraulic lime and 5 parts fat-free
cheese are mixed without water for about
two minutes using an electric mixer. This is
allowed to stand for some time, and then
20 parts hydraulic lime, 2% to 4% doubleboiled
linseed oil and water are added. Two
coats of this wash give a dry and wet wiperesistant
surface. Earthen pigments can be
substituted for some portion of the lime.
Borax-casein wash
Borax can be used instead of hydraulic lime.
It reacts chemically with casein in a way similar
to lime. With high borax content, crystals
form, which can be seen in the wash. Unlike
lime, borax does not give a white colour,
and is therefore preferable if dark colours
are desired. Chalk powder is added in order
to make the paint thicker and lighter in
colour. A small addition of clay powder
increases its workability.
If casein powder is being used instead of
fat-free cheese, it must be allowed to swell
under water for three hours (320 g casein
powder in 1 litre of water). Afterwards,
65 g of borax dissolved in 1 litre hot water
is mixed into the casein slurry and the
whole thinned with 12 litres of water.
Coatings
Lime, 2 layers
Chalk-glue, 2 layers
Lime-casein (1:8), 2 layers
Lime-casein (1:1), 2 layers
Fat-free cheese, 1 layer
Sodium waterglass, 1 layer
Lime-casein-linseed oil, 2 layers
van Baerle & Co., SILIN, 2 layers
Alpina, ALPINA PLUS, 2 layers
Auro, BIENENWACHS-STREICHBALSAM, 2 layers
Rifa, SILITANIT, 2 layers
Linseed oil, 1 layer
Water repellents
Wacker, BS 15, 2 layers
Metroark, SYLTRIT, 2 layers
Bayer, BAYSILONE IMPRÄGN.-EMULS.LD, 2 layers
Herbol, FASSADENIMPRÄGN. HYDROPHOB, 2 layers
Wacker, STEINFESTIGER H, 2 layers
Indula, HYDROPHOBIN, 2 layers
( ) = Proportion by volume
s d -value
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
0.00
0.00
0.00
0.00
0.01
0.02
0.02
0.03
0.04
0.00
0.00
0.02
0.02
0.09
0.10
0.39
1.22
1.45
Colourless casein coating
In order to retain the natural colour of the
loam surface while improving its wipe resistance,
a coating of the following mix can be
used: 1 part fat-free cheese with 1.8 to 2
parts water and 1 /8 to 1 /9 part of hydraulic
lime powder. This coating will give a colourless
to slightly milky surface, with a mild silky
sheen caused by its fine crystal structure.
Lime-suet coating
The following recipe from Nepal gives a
thick, pasty weatherproof exterior coating:
15 kg of powdered quick lime together with
99
Weather protection