What's the worse that can happen if I machine wash a shower proof jacket that says dry clean only. The outer shell of the jacket is made up of 53% Polyester 42% Cotton and 5% Polyamide?
probably not a lot, except that the cotton element could shrink a little if the water was above tepid. Also unless you handwash using a very mild detergent, the showerproof quality of the garment could be affected. Very gentle spin and dry on a hanger.
It's worth mentioning that High Street stores often put DRY CLEAN ONLY labels on garments as it is cheaper than having to invest in research to ascertain suitable washing directions for all the different fabrics they get in. I saw this on Watchdog!