Define "solid"!!
I had a mare with just a white star on her forehead, bred to my Rabbit (Red Dun with Flaxen but visually solid) she threw a full sorrel Pinto- and I threw a fit!! Secretary of the SPSBS calmed me down on the phone (he was a great old gentleman) and explained that the forehead star was quite enough, and no outlaw stallion had crawled under the fence in the night|! He forgot more about pattern than I am ever likely to learn, but he spurred my interest and got me started. That was 30 years ago, so what he was telling me was pretty revolutionary. So, as has been said, it is virtually impossible to get a true "solid" animal, and, especially where Rowdy lines are involved, I would test everything being bred for LWO as his lines in particular tend to throw up "solids" that carry LWO, with NO visual white at all. IT is all very interesting, I have learned to take what I am given, these days!