It has been years, like almost 20, since I did slipcovers for leather furniture. The first time I did it, the pieces had no loose back or loose seat cushions, and this made for a true slip cover -- in that it slipped because there was nothing to grab onto. I swore then that I would never do it again. And I didn't, until now.
My clients wanted to have this sofa and loveseat slipcovered. I explained to them why it might not be such a good idea, but they really liked these pieces and wanted to do it anyway. Since they were in the process of moving away from Coronado, and to make it a little easier for me, I went ahead and cut a pattern using a fabric I had, while the furniture was still close by. All they needed to do was find a fabric they liked and I would then make the slipcovers.
Jump ahead three years, and they still had not decided on a fabric. And by this time, they had moved back to Coronado. Finally, they found a heavy linen that they loved and ordered it.
Because they like a 'cleaner,' non-wrinkled look, they decided against having me wash the fabric, and will have the covers dry-cleaned.
Both pieces got the buttons down the back, more for the look than out of necessity in getting the slipcover on and off. And the wrinkles here will fall out in time. It is very difficult, oh yeah, impossible, to fold a slipcover, so wrinkles do occur. The overall look and feel, though, is not that of linen, but of a heavier fabric.
The 'new' sofa and 'new' loveseat with their existing throw pillows.
Although these turned out nicely, and having loose seat and back cushions definitely helps, I still would discourage slipcovering leather. The important thing, though, as always, is my clients were happy with the finished product and can still enjoy the furniture they love.