It's all about the technique!!

     From the very beginning Francis Bacon has devoted himself to painting, and only painting.  Never did he produce anything in preparation to his paintings.  With the exception of his triptych of Three Figures at the base of a Crucifixion (1944), he produced all his paintings on stretched canvas. 
     Francis found out by chance that he much preferred painting on the back side of a canvas, the side that was not coated in gesso.  He had run out of material and in a last effort try to finish the work he needed to for his deadline, he had to paint on the back of an already finished painting. 
     Bacon also would mix material, such as oil and tempera, in the same piece.  Often changing in paint because of the speed at which it dries.  He never varnished his paintings, instead he'd rather cover them with glass at a later date, when he was sure it was completely dried, and would accept the glare and minor distortion it caused to the painting.
     In most cases Bacon would paint with the traditional paint brushes, but on occasion he would use his fingers, are press a cloth on to the wet surface to give it a texture.*


*Ronald Alley. "Bacon, Francis." Grove Art Online. Oxford Art Online. Oxford University Press, accessed April 28, 2014, http://www.oxfordartonline.com/subscriber/article/grove/art/T005594