In order to make our oil colors archival we use water-washed, virgin cold-pressed linseed oil as the vehicle to disperse our pigments.
Conservators and conservation scientist - recognize cold-pressed linseed oil (CPLO) as the best drying oil for binding pigments. It has a uniquely high alpha-Linolenic acid content that creates a dense polymerized network of double and triple bonds that cross-links through the paint film.
To avoid a rancid, discoloring oil it must be refined of it's water-soluble mucilage.
This photo below shows the mucilage that is left behind after we remove the cleansed oil. In the image on the left you can see the mucilage being separated out and trapped between the oil (on top) and the water (below). The image on the right is a bird's-eye-view looking through the oil (on top) to the trapped layer of water-soluble mucilage.
"No oil is fit for a varnish or a vehicle, intended to be durably brilliant or durably light, which has not been thoroughly freed from its mucilage."
– Sir Charles Eastlake
Conservation Science – CPLO is more durable...
A recent scientific study: Oil Paints: The Chemistry of Drying Oils and the Potential for Solvent Disruption by Charles S. Tumosa and Marion F. Mecklenburg has shown cold-pressed linseed oil to be superior to all other drying and semi-drying oils for sustained weight gain leading to more polymerization and to a stronger paint film.
"Figure 1 plots the long-term weight loss in several oils over 1200 days. Note that the cold-pressed linseed oil loses far less weight than the other ones. Some of the oils are lighter in weight than when first applied, indicating severe degradation of the oil film polymer, which can continue for several years."
The passage of time proves CPLO's superiority
"This is what the LORD says: Stand at the crossroads and look. Ask which paths are the old, reliable paths. Ask which way leads to blessings" Jeremiah 6:16.GWTFrom around 1410 AD when Jan Van Eyck is credited with inventing oil painting, virgin, cold-pressed linseed oil has been in use by oil painters! The refining method used for centuries has been washing cold-pressed linseed oil with water to cleanse it from its mucilage. Science has confirmed the most durable of historical paintings were made with oil colors ground in cold-pressed linseed oil and were virtually (and in most cases) resin-free.