The first Babson black, Fa-Serr, was born in 1947. He sired 20 black foals and no chestnuts.
Fa Serrīs influence was multiplied by his sons Fa-Rousse (24 black get), Khemahr (20 black get), Ozem (29 black get), and Negem (17 black get). Of these four sons, Negem was the only one that did not sire any chestnuts out of 93 offspring. Negem, who is very often forgotten, appears to be the unsung hero here and is responsible for several unbroken lines of what can be considered to be homozygous black.
The Black Mystique (Margo Weise):
http://www.arabianrun.com/black2.htm