Also, make dead sure that the patching is 100% cotton. If it does not say that, don't buy it. You don't want to clean burn-on polymer out of your bore. Ick.
In my experience, the sizing in the patching prevents the lube from getting into the fabric, and it is stiffer at the muzzle and so makes loading harder. So yes. Wash it before use.
I buy the 100% cotton canvas (untreated, NOT teflon) from The Minute-Men patching. Only call. In the evening. I don't think he uses email and the website doesn't work. Best patching material in the world, and the price is not bad compared to Joann Fabrics. This stuff never burns through.