For years, I have always wondered what to do about my socks when they start getting threadbare. They either wear thin at the toes or the heel. They become embarrassing if you wear them out and have to take of your shoes in company. It seems like a waste to throw them away and they would be gross to donate. So, now I convert mine to shop rags before they are unpresentable. Since they have been washed probably close to a hundred times, they are virtually lint-free. If the clean-up is not toxic or oily, they can be washed and re-used again. I store mine in a zip-lock bag in my shop to keep them clean after washing. These are pictured next to fragrance-free baby wipes, which are another essential item in my shop.
For wood working projects, they are great to use for a final rub down prior to finishing. In the two pictures, I use a clean old sock to rub down the wood. The wood is noticeably smoother after the rub down and the sock has attracted and captured a good amount of dust that the vacuum did not get. The sock on the left was used to rub down the wood. It is darker than then one on the right from the collection of dust. For me, these work even better than the tack clothes that are sold for the same purpose. Old T-shirts perform similarly. For staining and finishing, pieces of old t-shirt also work well applying the stain or finishes. On some projects, I used go through several brushes during the finishing process. now I just cut down a small piece from a old T-shirt and use it to apply the finishes. This works best for finishes that require a very thin coat. Some finishes will need the carrying capacity of a brush.
So, instead of buying additional rags, give your old socks and t-shirts a second life in your shop!