I might have finally found a solution to protecting the back of my paintings. I haven't been painting for that many years, but it has always bothered me how vulnerable the paintings are from behind. I am also surprised at how little there is written about this subject.
From a conservational POV, I think the popular belief is to let the painting breathe, and to not enclose the painting at the back. Because it can cause problems like the back of the canvas not getting enough air to it, which can effect the paint on the other side - as the front and back are not ageing at the same speed.
But being exposed in this way makes me uncomfortable, because the painting is prone to accidental damage, particularly when it is laying around whilst waiting to be hung safely up on the wall. I very nearly damaged a painting once by not being careful enough, and I leant it against the corner of a piece of furniture, and didn't realise that the canvas was getting a small indent at the point where it was making contact.
Dust building up in-between the stretcher bars and the canvas can also be a problem. In extreme cases, I have read that this can cause the canvas to bulge forward by a large amount of dust. That does seem unlikely, but keeping dust from getting in there in the first place is another good reason for protecting that side of the paintings.
From a personal POV, having grew up with my Dad, who was a photographer, and watching him add a backing board, and sealing it into an elaborate frame with brown framer's tape, somehow it gave it a professionally finish look.
After trying to find a solution, I stumbled upon a material called, Tyvek from PEL Preservation Equipment. It's got many conservational qualities, and sounded perfect for what I was looking for. This was my first solution:
I was happy with this, but overtime whenever I handled this painting, it didn't strike me as being protected as much as it should be.
Anyway, after reading this article from the Canadian Conservation Institute, I had finally found something that agreed with me that it is good practice to use a harder board to protect a painting.
I have modified it slightly, because I was having difficulty finding the foam strips, and some of the specific boards that it recommends. My theory is that, so long as I have the Tyvek in-between the backing board and the canvas and stretches, then it would be safe to not use the foam. I was also concerned that the foam would extend the backing too much, and my paintings would stick out from the wall too much.
So time will tell, but this is a simple and professional solution to the backing of my paintings.