Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Great until you use it

I bought one of these for a Scuba Trip to Key Largo. Originally I was going to purchase two, one for me and one for my roommate, but after reading the reviews decided on one and that if it was great once it arrived I would order another.First of all the knife itself is attractive, has a hard plastic handle and the release worked well. We were thrilled with it and I gave it to my roommate to wear while were were diving.The first day of diving went well, no problems with it. We got back to the hotel and soaked everything to get the salt off of it. The knife was washed in the sink and towel dried. The next morning the blade had started to rust. I was extremely disappointed in this fact, that after a single use the blade was rusted.I did not end up purchasing a second knife.