My machine absolutely refuses to quilt microfiber sheets. Major major issues, but I haven't had a problem with 50/50 . I still look for 100% cotton but sometimes that 50/50 is the perfect colour or design. Anything that comes into the house from thrifting, goes directly into the laundry. Biggest issue for me, is previous use of dryer sheets. The 'stench' (and to me it is a stench, not a pleasant odour) gives me a severe headache.