1. This stuff can really burn you. I have had 3 serious burns with this -320 liquid. The worst one happen about 3 months ago when I did a demo at whole foods with my wife. I filled my sorbet bowl with strawberry puree to accommodate all the people watching. I had to much product and not enough spoon. The nitrogen will freeze your nerve endings so quickly that you don't react to the pain like you would a heat burn. My thumb was in the liquid for over 10 seconds. My thumb blistered to about 3 times it's normal size and it was pretty jacked up for about 6 weeks. Nitrogen burns take twice as long to heal as a heat burn would. I would compare the pain to frostbite if you have ever had the pleasure of experiencing it
2. When filling your dewar you need to make sure that the container is cold. Liquid nitrogen is expensive and you loose a lot of it when you are filling a warm container. I will leave our 25 L dewar in the freezer overnight before I fill it the next day. We do this so it takes less nitrogen to bring the dewar to a temperature that will hold the nitrogen.
3. Don't trust anyone to handle it. Especially look out for drunk people and small children. It is the chefs responsibility to make the demonstration safe and lets face it kids don't know and drunk people don't care.
4.Make sure the liquid nitrogen is completely evaporated before giving it to someone. The space foam is a favorite technique here. The structure of the foam will allow small pockets of nitrogen to form. I have burned my tongue pretty bad because I did not wait long enough for the nitrogen to burn off. We also like to do marshmallows in LN for the kids. Kids have very sensitive tongues so it is important to make sure that it is safe
5. Where protective glasses, not protective gloves. My first thought was to wear latex but that was a very bad idea. I have also tried to wear welding gloves but I actually had some spill inside and they are not very sanitary. My advice is to get a very long spoon. The nitrogen will splash out of the bowl so it is important to wear glasses and make sure you are far enough away from the guest so you don't splash them
6. It is a great show. Remember table side when it was fun. Ceaser salad, banana foster, you just do not see it anymore. This gives us the opportunity to say hello to the guest and make them a unforgettable course at the same time. Again I will point out that it sucks making sorbet for drunk people, everything is a joke
7. This is not science fiction. This is the best way to make ice cream and sorbet. As a chef I am always looking for the best technique to make the best product. If I could throw a steak in the microwave and it would be the best steak I ever had I would repeat it again and again. Yea its a fucking microwave but it made the perfect steak. Yea it's nitrogen, a very cold mysterious liquid, but it makes the best product. I will take a tank of the cold stuff against your hand crank any day.
8. By a new dewar and not a used one. Even a small crack in the tank or the plastic top will allow the nitrogen to escape. A 4 liter dewar will loose it's contents in less then 2 hours.
9. Have fun, this is the most amazing medium that I have ever played around with. Next I am on to liquid helium and super flows