You can find bluer, redder, greener, and whiter in the dictionary, but not blacker. This seems mystifying.
In his "El Paso" song, Marty Robbins sang,
"Blacker than night were the eyes of Felina."
During the recent Presidential campaign, some pundits asked,
"Is Mitt Romney blacker than Barack Obama?"
NASA has created a new nanotube material that is
"blacker than black paint," according to various published reports.
There are several official shades of black, such as taupe and ebony, leading to the presumption that some shades are "blacker" than others.
Since "blacker" is not in the dictionary, would the proper usage be "more black"?