Since Roc-Lon is supposed to be a higher grade of muslin, do you still pre-wash it?

I bought a bolt to use for quilt backs, but I need to know...

Thanks,
MJ

I prewash everything except precut fabrics-I always have this fear of bugs or bug eggs being on them while they have been sitting in storage somewhere.

I would cut off a strip, measure it and then wash and dry it to see how much/if any it shrinks. :D:D:D