Just came on board and would like to share my findings please.
I've sprayed G2 and Slick Sand for quite a few years and in my research and "experimentation" this is what I discovered to be the difference: :
Featherfill G2 (Generation 2) and Slick Sand are both high-build polyester primer surfacers.
G2 was made to be VOC (Volatile Organic Compounds) compliant nationwide – though I heard this product was originally designed to be used in California.
Slick Sand is also VOC compliant.
Both G2 and Slick Sand can be wet-sanded unlike the original FeatherFill that you had to wait at least 24hours to ensure it did not retain moisture.
G2 comes in different colors: Buff (cream color), Gray and Black
Slick Sand is only available in Gray
G2 can be used over (and is recommended by the manufacturer) 1K or 2K etch primers. (1K = 1 part; non catalyzed; 2K = 2 part; catalyzed)
Slick Sand has excellent corrosion reisistant over bare steel.
G2 is Tintable, up to 10% by volume with most polyester basecoat tints. I've never tinted my G2 with basecoat tints though I've “cocktailed” G2 with other G2 color primers; e.g., I "cocktailed" Gray G2 with Black G2 to achieve a charcoal colored primer prior to topcoating with a Satin Black finish.
Slick Sand cannot be tinted.
Both G2 and Slick Sand have the same Solids % by Volume: 57-62% if you follow the manufacturers reduction ratio!
G2 has a suggested flash time of 5-10 minutes between coats @ 75 degrees.
Slick Sand suggested flash time of 10-15 minutes between coats @ 75 degrees
Both G2 and Slick Sand are dust free in 30 minutes @ 75 degrees.
G2 Dry-to-sand is approximately 1.5 hr @ 75 degrees F (if used over etch primer will extend this time)
Slick Sand Dry-to-Sand is 1.5 – 2 hours @ 75 degrees F
*This is the manufacturer tested times and are averages. It will also depend on the amount of coats you apply, how much reduction etc., - the more coats the longer the D2S time!
G2 should be sealed prior to topcoat.
Slick Sand does not require a sealer prior to topcoating but I myself make it a habit to seal everything prior to topcoat color application.
Both G2 and Slick Sand are Isocyanate free thus reducing health risks.
G2 needs reduction for good sprayability.
Slick Sand does not require reduction though I've reduced it with even better sprayability.
G2 has a pot life of approximately 25-35 minutes @ 75 degrees F
Slick Sand has a pot life of approximately 45 minutes @ 75 degrees F
I suggest you don't keep either of these products in your gun longer than 30 minutes or you'll need to buy a new gun!
Both G2 and Slick Sand are best sprayed with a 1.7 up to 2.2 fluid tip/air cap. Anything smaller in size will require more reduction of the product for satisfactory sprayability, thus having to apply more coats to achieve the appropriate DFT (dry film thickness) due of the the reduction of solid content.
Both require a minimum of 2-3 wet coats. Do not mist coats!
G2 and Slick Sand can be used on rigid and semi-rigid plastics.
Hope this helps!!