Notes on Griffin alkyd paint

Was just browsing their website and ran across this info, which I want to remember (this blog is my substitute for a proper functioning memory).


Whites
The three whites which are available in the Griffin Alkyd Colour range offer the artist different working characteristics. Titanium White is the most popular modern white. It is the whitest, most opaque white and gives excellent covering power in a painting. Mixing White is the most transparent white available which makes it ideal for tints and glazing.

Each successive layer must dry slower

This one I had never heard before. I know about the fat over lean rule, which essentially means add more medium to each successive layer of paint. But apparently since a layer isn't really completely dry when you paint the next layer (only touch dry, and still shrinking slowly) you need to make sure the next layer will shrink slower - makes sense. But the instructions on how to achieve this on the website are contradictory. They say to add more medium, and they specify Liquin, which they say elsewhere actually cases the paint to dry faster. Huh? 

I thought about this a bit, and realized what you need to add isn't more alkyd medium, but more oil instead. Walnut oil slows drying time, while the walnut alkyd medium speeds drying time. So it's pretty clear-cut - use either straight paint for the 1st layer the way alla prima painters often do, and add some medium to the next layer, and for each successive layer add medium plus more walnut oil each time. Though I don't usually need to do more than 2 layers (might go past that on complex paintings I suppose).