.

[charlotte]

I always think of pre-washing fabric as a thing invented our friends across the pond who put everything in their tumble dryers... That said, I do try usually prewash if I am planning to wash the finished garment in the machine, or at the very least (when I am impatient to get started) give it a good spray and a hot iron. As others have said, it's not worth the risk.

[elephun]

I think that's me! Across the pond.

I've had countless storebought blouses/tops shrink from perfect to past wearable the first time they were washed in cold and hung to dry. I would never wash clothes from a store at anything but cold or tumble dry them- they would be ruined! Denim continues to shrink over many washes, so jeans that are just barely long enough when purchased start to look silly in short time.

Yes, I wash and tumble dry pretty much all fabric as soon as I get it to shrink it, get nasty chemical finishes off, and give it a chance to start pilling or otherwise going bad before I've spent anything but money on it. I can't afford to waste money, but as I don't feel well so often, I can't bear to waste good time on bad fabric!

[UttaRetch]

I always wash everything. Why not? It just seems silly to me to take the risk when it requires you to do so little work to wash it (bung it in, hang it up).

What about pressing it to get out the creasing caused by the washing?  I didn't prewash fabrics or even press before cutting and all I ever needed to do was smooth out the folds. 

[Francesca]

What about pressing it to get out the creasing caused by the washing?  I didn't prewash fabrics or even press before cutting and all I ever needed to do was smooth out the folds.

I usually press just before I start sewing, with my steam iron. I don't find things that are either hung or tumble dried take much time at all to press, 5 minutes tops for 3m which is my standard (it's usually just the edges that crinkle the most). It's also a good way to get an idea of the handfeel of the fabric and how it behaves so you can prepare whether you might need to cut it in a particular way or starch it.

[BrendaP]

If it takes a lot of pressing after pre-washing you know in advance that the finished item will need a lot of ironing.