Painting should be carried out during damp periods, and the painted surface protected from direct sunlight for at least 14 days after it is complete.The walls to be painted should be moistened beforehand with lime water - part of all lime paint recipes. Lime water is made as follows:
1. 'Wet' slaked lime is mixed with water in a proportion of 1:5.
2.The mixture is stirred well until all lumps are gone.
3. After 24 hours all the lime has sunk to the bottom. The water above the lime is lime water.The layer of crystals that has formed on the surface must be removed. Lime water is strongly alkaline, with a pH of about 12.5.
Lime milk is also an important ingredient in the paint. It is quite simply a dispersion of solid slaked lime and lime water in theform of lime solution. Avery fine grained calcium hydroxide with particles of about 0.002 mm arises through slaking. Lime milk is prepared in the following way:
1. Fresh 'wet' slaked lime is mixed with lime water in a proportion of 1:5.
2.The mixture is stirred well until all the lumps are removed. After about 10 minutes, a good lime milk is created. It can stand several days before use.
Limesurfacesruboff, butthis can be retarded by adding a little collagen glue (see page 399), to the lime solution.This method is only for use inside a building.
The pigments best suited for lime paint are ferric oxide colours (yellow, brown, red, black) and ultramarine, which tolerate lime.The pigments should be mixed with water and madeintoathickgruel.
Limepaintcan best be directlyapplied onto completely fresh render, and there is seldom the need for a second coat. Old, decayed render, or lime or cement paint, must be brushed clean of dust and dirt ifthe paint isto bind properly. Lime needs several days to become properly bound to the surface. It is important that the render and the layer of paint do not dry out during this period. In particularly dry weather, the wall should be watered when it feels dry, especially if it is exposed to direct sun.
RECIPE 1: WHITE LIME
The surface is painted with lime water, followed by two or three coats of lime milk, then another coat of lime water.
RECIPE 2A: RED LIME
The earth pigment red ochre is soaked in two parts water overnight to become a pigment paste. The soaked pigment is then mixed with lime water in a proportion of 1:9, to become a lime paint.The wall is first given a coat of lime water, then a coat of lime paint, and is finished of with another coat of lime water.
RECIPE 2B: YELLOW LIME
The earth pigment yellow ochre is soaked in two parts water overnight to become a pigment pasta. The soaked pigment is then mixed with lime water in a proportion of 1:9 to become a lime paint.The wall is first given a coat of lime water, followed by two coats of lime paint and finally another coat of lime water.
RECIPE 2C: LILAC, BROWN OR GREEN LIME
This is made with the pigments ultramarine, umber and burnt umber.The production and application are the same as for yellow lime, above.
RECIPE 3: YELLOW LIME WITH GREEN VITRIOL
This paint has a certain antiseptic effect in addition to the actual effect of the lime. A solution of green vitriol and water in a proportion of 1:5 is made.Then a separate mixture of'wet'slaked lime and water is made in the proportions 1:5.The two mixtures are then stirred together to become a thick porridge, and water is added. Before painting, the surface is treated with one or two coats of lime water.
RECIPE 4: LIME/CASEIN PAINT
By adding casein to the lime a casein glue is formed which, apart from having better opacity, is also more elasticthan ordinary lime paint.This is thetype of paint that is used in fresco painting and for wooden surfaces.The paint is waterproof. One part of 'wet' slaked lime is mixed with half to one part of curd (containing about 12% casein), and all the lumps are pressed out. For a purer casein paint, four parts curd are used. To the mixture isadded20-40% stirred pigment oftitanium oxide, redoryellowochre, umber or green earth and thinned out with skimmed milk. The surface is given a coat of lime water before painting.
RECIPE 5: FLOOR TREATMENT WITH LIME
Lime treated floors are light and easy to maintain. First sand the floor and vacuum it. Slaked limeand waterare mixed in a proportion of1:10.The gruel is brushed evenly over the floor with a broom. When dry, the floor is sanded and vacuum cleaned again, then
18.3.2 Silicate paints washed with a 5% solution of green soap in lukewarm water. Cleaning of the floor is also done with a 5% green soap solution.
Silicate paints have their origin in the binder potassium waterglass (see page 90), and were patented in 1938 by A.W. Keim. They can be used on all mineral surfaces but also give good results on rough wood. They can be used as an opaque paint or as lazure paint. Waterglass paints react with lime on a painted surface and form calcium silicate, which acts as a binder. The paint film forms a crystalline layer that has a high resistance against acids. The best results are achieved on fresh render. This paint is more durable than lime paint and has a strong resistance to pollution. Its vapour permeability is about as high as that of lime products.
Some silicate paints have acrylates added to a maximum of 5%, which forms a dispersion product. As long as the surface contains lime, added acrylate will not make the paint stronger. It can also be assumed that the added acrylate shortens the effective lifespan of the paint. For pure waterglass paints, pigment has to be added on site, whilst paint with acrylate additives is ready mixed from the factory.
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