So I am a home cook, I am interested in purchasing a Dewar. I am just not sure what size I should be purchasing. I know my local welding shop sells liquid nitrogen so I have access to it in my area. I am looking to use it to make ice cream mainly, maybe once a month, and to make some herb dust. A friend suggested I get a 4 liter because it easy to handle. However, I am not sure how much nitrogen it takes to actually make a quart of ice cream. Anyone have experience with nitrogen and suggetions?