Using standard biodiesel transesterification procedure, 100 ml. of linseed oil is mized with a prior-made solution of 40 ml. methanol containing 0.4 g NaOH.
The solutions are mixed and stirred at 50-55 degrees c for 1.0 hr., cooled and lower layer of glycerol/methanol tapped off.
Usually, at this point, biodiesel is washed and dried before use as a liquid renewable fuel. I use the biodiesel directly in. mulling pigment since small amounts of glycerol aid in brush flow on surfaces.
In the manufacture of 'alkyd resins', a vegetable oil is heated with glycerol and catalyst (PbO or Sn (II) oxalate) at 220-250 deg C under N2. The resultant mono-ester is then reacted with phthalic anhydride to form the alkyd resin. Most oil-based paint manufacturers rarely use linseed oil directly in past decades.
The linseed oil biodiesel has the same color as the commercial boiled linseed oil used. The biodiesel is less viscous than linseed oil, dries overnight to touch -dryness and also cleans brushed well. Its use avoids the need for toxic turpentine use.
Mulling of pigments is also easier to pour and the biodiesel can be blended with wax ( or crayon containing pigment) to an impasto cold wax paint.