I have owned a black leather sectional for about 20 years. For 15 years of that time it sat in front of a bank of windows. I was busy raising children and didn't notice it was fading.  When I moved it became apparent that it needed attention. It had turned a very light gray on the back. I searched the web and luckily found Leather Therapy. I treated it with the restorer/conditioner and it immediately turned back to black.  It simply drank in the product. I was so thrilled and surprised, that I left one section unfinished to show everyone how well it worked. 

Peggy S.