Galkyd Or Galkyd Lite Is Liquin Fine Detail A Substitute For Classical Copal Glazing Medium?

Is Liquin Fine Detail a substitute for classical Copal glazing medium? - galkyd or galkyd lite

For portraits of art in the last copal medium gloss, enamels, glazes, as used in layers Grisalla sketch. The resources of the copal was hard and cracked. Internet and art shops, I found "Copal" and "copal-like" funds available, but must Grumtine or turpentine and thinners.

I tried walnut / alkyd medium Liquin and Galkyd Lite, not for me. (I can go back to 1 / 2 linseed oil and 1 / 2 Turpenoid or Gamsol.) I have to keep trying, half of the copal. It should produce enamel, as the enamel, no cracks in 20 years.

Winsor & Newton said Liquin fine detail can be a substitute for Copal, but will not find much in the way of information or an artist who has experience at first hand. (Sounds like this is to say with the odorless spirit (OMS) (related Gamsol) in line.

Now my question:
1. If you've used Fine Detail Liquin as a substitute for the copal, as you have done it. Have Grisalla glass? Do you have an extender, if so, how?
2. Is there a product that was used to ensure the quality of the artist as a brilliant emails?
3. Do you have the Grumbacher Copal Painting Medium, and what were the results?
4. I looked for Mr. Graham. To find Gamblin, Grumbacher, Winsor & Newton and other manufacturers of art and places, without much in the way of details. All the relevant link would would be received with thanks.

Thank you in advance for your generous support.