Rublev’s new version of sun-thickened oil is much improved from its earlier offering and is good oil. This is far different from my conclusion of their first attempt at this product. Sun-thickened oil’s consistency should be similar to that of stand oil. Rublev’s first attempt produced an oil little different from regular linseed oil.
With this iteration, Rublev has finally provided an oil with the right thickness. For those unfamiliar with thickened oils, stand oil is made by heating oil in a vacuum. This results in an oil with the consistency of thick syrup. Normal linseed oil’s consistency is closer to water than syrup. Stand oil imparts a smoothness that many find pleasing. Stand oil is readily available.
As the name implies, sun-thickened oil is made by exposing the oil to the sun. Through oxidation, the resulting oil has a consistency similar to stand oil, as I already mentioned. Unlike stand oil, however, an oil thus treated maintains brush strokes and imparts body and brightness. It’s the best of all oils for many use cases.
The best versions of sun-thickened oil that I’ve used have a consistency thicker and stickier than even stand oil. Rublev’s version is closer to stand oil in consistency. So, even though it’s not the best sun-thickened oil, it is a good oil.
To make sun-thickened oil, you need strong and prolonged sunlight and a lot of time. The oil should remain exposed to the sun for at least 3 months. This means that even though you don’t need high heat and expensive equipment to make sun-thickened oil, commercial producers rarely offer it.
If you live in the right type of climate, you might make your own sun-thicken oil. Get some good oil and put it in a glass tray, and then expose the tray to the sun for at least 3 months.
By the way, another variant is to place the oil in a leaded tray. For this variant, you don’t even need strong sunlight. The resulting oil is thick like stand oil but tighter than either sun-thickened or stand oil. This oil has its uses but I much prefer sun-thickened oil.
I’ve had good success producing my own leaded oil, but not very good success attempting sun-thickened oil. I live too far north I’m afraid.