What blade sizes should I use for my horse?
Answer from professional horse groomer: Brooke The Clipper Girl
"Loaded question! Every horse's hair coat, color, and even growth rate is different! In general, I tend to clip lighter color (think palomino, cremello/perlino, light colored buckskins, white, etc) with a longer length blade such as an Andis ShowEdge #10 or T10, or the Andis UltraEdge or CeramicEdge size #10 or #15.
I always make sure my first clip of the year is also with a 10, regardless of color. Stripping the color off too close too early in the year (late winter/early spring) will only make it harder for the hair to grow back with luster and color, from my experience.
Darker horses like Roans, blacks, dark buckskins, chestnut, and even pintos can be done also with a size 10, however, a ShowEdge #30 or UltraEdge or CeramicEdge #30 is also a good choice for these colors.
Towards the end of show season, for example, the Nationals and the World show, (think, fall) almost all the horses I clip can be done in a size 30 blade all over. This time of year the horses are growing coats like crazy, dark color should be at its peak, and generally, it's pretty safe to use a 30 on most horses at this time when showing."