Hello Alison!
Thanks for bringing this great question to us at planDisney! I too had seen different reports and information about different hairstyling tools that are allowable on the Ships. So, I went right to my favorite source: a Disney Cruise Line crew member!
"Hairdryers, curling irons, and flat irons may be brought onboard as long as they support the ship's electrical system. Those items must be 230V and 450 watts or less. At this time the ship's electrical systems are not able to support Dyson or Shark products; therefore, Dyson and Shark products may not be brought onboard." Each room is equipped with a hair dryer, so no worries there. As long as your flat iron is below 450 watts, all should be well.
If your hair appliance doesn't work I think that would be a great excuse to go to the
Untangled Salon! This cleverly themed salon can be found on both the
Disney Wish and
Disney Treasure. They will get "everyone neat and pretty" in no time! On the other ships, you will find all things relaxation and beauty at
Senses Spa & Salon.
I hope this helps! If you have more questions, come on back to planDisney- we love to help!
Anne