 Remember to label any container before you add the liquid. This will prevent the liquid from touching the lid when you manipulate the container to write on it. Open the lid and place it back on top of the container so that it is easy to lift when you are ready to add the sterile liquid, like the Sarkocher medium, for instance. And wrapping sterile pipettes is an art. You should remove the paper wrap without touching the portion located towards the tip of the pipette that will be later on in contact with the sterile liquid. Once you have opened the paper wrap a third to half of the way, place the pipette in the pipette holder by holding the pipette towards the top away from the part that will be in contact with the sterile liquid, and making small twisted movements to firmly anchor the pipette, grab the end of the paper wrap, and quickly pull it off the pipette. Note that placing the pipette in the pipette holder can also be done last. You should always be aware of where the tip of the pipette is. If it touches anything, the pipette should be changed to reduce the risk of contamination. The main bottle of medium is the most critical container. If it becomes contaminated, every single cell culture will be contaminated during new cell seeding, as well as during times when medium is changed in the cultural vessels. As always, make sure that the end part of the pipette where the tip is never comes in contact with the neck area of the bottle or the top of the container. Go straight down the bottle with the pipette, take the amount you need, and then carefully pull the pipette up the bottle, hold the lid with the other hand if possible, and place it back immediately on the bottle after you have taken the liquid from the bottle. When placing the liquid inside a container, make sure that you do not touch the area of the top of the container with the tip of the pipette. You should hold the lid in the other hand and place it back immediately on the container after adding the liquid. Remember to put the lid back on top if you are not going to use the container soon and tighten it. The same pipette can be used to fill multiple containers at once as long as you are sure that the tip of the pipette will never touch anything but the sterile liquid. It is usually not recommended to go back with the same pipette in the main bottle of medium unless you are really expert at manipulating in cell culture.