Is there a way to tell if fabric has dry rot before you sew with it or do you have to wash it in order to do this? I have used some old (i guess) black material from my mil's stash in a quilt and it just fell apart literally when I washed the quilt. Thank goodness not much time was spent on it and it was small. The material just ripped and even seem to disappear! I just tossed it away from frustration and didn't think to take a pic to show you. Has anyone had this problem before? She had washed it but it could have been 30 years old and I don't know how it was stored.

I have never had it, but I think you would probably need to wash it just to be safe.

To me if it was dry rott then it would tear easily. Give it a tug with both hands and see if comes apart. Just like when testing thread to see if it is old.

I don't know about dry rot, but my friend used black that she had purchased from Joann's years (before 1996 anyway) ago. She used it in the center of log cabins, and when she was hand quilting it, her finger went right through the fabric. She painstakingly removed each piece & hand pieced another little square into the sandwich.

I would do some tugging, pulling and stretching on it... if it won't hold up to that, I would not use it :D:D:D

Whew after seeing this I would toss it if I had any doubts about it. I have never seen fabric with dry rott to know. That would be a major frustrator though if that would happen.
I wonder if washing it with some vinager would help though.

I wonder if this could be the same for me. It was not exceptionally thin and while I did not tug hard, I do recall pulling on it. I feel pretty sure it wouldn't rip then. Thanks for all the help/suggestions!

i have had relatively new black fabric do that. One good reason to prewash fabric.