Civil Engineering Reference
In-Depth Information
inhalation routes. Linseed oil paints are relatively open to vapour transport and
only slightly reduce the vapour-regulating potential of the substrate. The prod-
ucts do not cause electrostatic charging.
Materials treated with linseed oil are difficult to clean and therefore have less
chance of being re-used. The same is true for recycling. Energy recycling is pos-
sible without filters for the fumes, as long as fungicides and problematic pig-
ments have not been used. As waste, products with no pigments or fungicides
can be ground and composted. Consideration must also be given to what drying
agents have been used, before treating the waste.
Recipes for linseed oil paints
Linseed oil paints can be used both inside and outside. For interior use, linseed oil emul-
sion paint is the best choice (see p. 424). Linseed oil paints are particularly well suited to
external walls of timber panelling. It swells in damp weather and creates an elastic film
which is never completely hard. When linseed oil has set, it is porous to water vapour and
allows moisture to evaporate. The choice of pigment is important if the paint is going to
retain these properties. Zinc white should not be used as an outdoor pigment. It is easily
washed down by acids, rain and dew, and when exposed to ultraviolet radiation the paint
starts crazing, especially on a south-facing surface.
Recipe 1: Normal linseed oil paint for outdoor use
To start mixing linseed oil paints prepare a colour paste where the pigments are well
mixed with a small amount of linseed oil to an even consistency. The amount of pigment
depends upon how transparent and shiny the paint is to be; more pigment will give a more
matt paint. The pigment paste is mixed with the oil.
The first coat usually contains about 15 per cent vegetable turpentine to help the oil
penetrate the substrate. The final coat does not need solvents, especially if cold pressed
oil is used. Adding solvents to the paint generally shortens its life span.
Recipe 2: Linseed oil treatment of timber floors
The floor should be sanded. The first coat usually consists of a mixture of mineral or veg-
etable turpentine with boiled linseed oil or stand oil in the proportions 1:1 and in the final
coat in the proportions 1:2. After application, all the excess oil be dried up after about 20
to 30 minutes.
Paint with fish oil binder
Fish oil has been used a great deal in coastal regions up to the beginning of the twentieth
century.
Recipe: Normal paint with fish oil
Fish liver is laid in a barrel and put in the sun with a sack pulled over the top. The liver
melts quickly to liver oil, is mixed with English red or other pigments and can be dis-
solved in alcohol if necessary. The paint is very durable and has good resistance to
salt water.
