I have a jumper that is 80% merino wool 20% nylon, the washing instructions are handwash.
I have a wool wash on my machine and the coldest wash temp is 30degrees. I wash machine washable cashmere and machine washable wool on this setting/temp and never had a problem.
I can't stand the thought of hand washing this merino/nylon mix jumper another winter, is there any reason why it shouldn't go in the machine.