I've not been able to find anything at fabrics stores, but I might not be using terminology which they are used to. I used to purchase good linen from woodfinishingsupplies.com, but have not found a suitable source since. Basically looking for durable linen with mild abrasive qualities that doesn't shed into the finish. Sure hope there's a supply out there outside of old tablecloths and handkerchiefs.
Millcreek, do you have a URL for the Mowhawk cotton product? I'm not seeing it with a simple google search, but again my keywords may not be correct for the fabric industry.
Thanks.