I tend do get skipped stitches when using sheets on my long arm, the reason most won't use them... I don't want you to have issues with my quilting....

I quilt on my Janome 6600 and will use what I have or can find for backing. I've used regular quilting cottons, wide backing, flannel, and sheets. I've never had any issues with any of them and always wash all of them before using. Using a sheet as a backing can be a great thing if you are doing a kids themed quilt....kids love the prints and very easy to get an extra sheet to make matching curtains.

I have a longarm, and will not use sheets. I did for only one quilt, and that was because it was a family member, whom I did not want to offend. I do not recommend ever using sheets. They are usually too poor quality, and if you do get better quality, then you have to pay more, and you might as well use a good quality fabric. I also had to take the hem out of this sheet, and wash it prior to putting it in the rack.

I buy king flannel sheets for backing for queen quilts. Perfect for summer quilts! Penny's has sales reg and I get them and just wait for a top to be ready! I normally buy netural colors and always wash them before sending them w/top to my quilter.

I would wash the sheets - to go with the washed top fabrics -

It seems to me that if one buys sheets that are similar in weight and weave to 'quilting fabric' - that there would not be any issues.

Although I have a serious issue with the words 'suitable quilting fabric' - seeing as I come from an era where velvets, denim, silks, cottons, rayons, wools - were used - probably anything and everything except cheesecloth and burlap!

(I'm not saying that all these combinations were 'successful' - just that they were used)