In order to make sure the thread knots that I tied in the back did not pull through our chip board backing, I used two leftover buttons as a backing before tying the knot. Nothing pretty of course, just two buttons from our stash of extras that are saved for that unfortunate incident when you pull your pants out of the dryer, only to realize they are now buttonless. And in the end, our technique stands up to our tests of sitting down into the chair in the bounciest ways possible. Luckily all of Andrew's handy man (or as he calls them, handy Andy) tricks have been concealed with the final backing of fabric.
In the process of making a new cushion, I lined the old springs with burlap and then covered that with the seat cushion before adding the final upholstery. All in all, our final product is spectacular-- keeping to the old chair's vintage look, yet adding a modern and contemporary flair. And of course, now for the obligatory before and after photos. Enjoy!