I go into this pretty extensively in the PDPC course. They are not the same. Solvent Free Gel is 100% fat. Please check out Module 3 Lesson 5 in PDPC - here is a screen shot of the slide that explains the difference. I'ts a little complicated, but the answer is YES you can use it instead of GGel, But, just be aware that you can mix Galkyd Gel with Cwm as high as 9:1, but with SFG, the highest ratio you should mix with CWM is "up to 1:1". It's a little technical and easy to forget, so that's why it's good to print out this attachment!