ANSWER – The first thing is deciding how to obtain it as that will determine some of the methods you can use for storage. For witches who are comfortable using a moon cup (a small plastic cup that sits inside you and collects the flow) the blood can easily be poured directly into a container. The most hygienic way of doing this is to freeze the blood – have a specially designated ice cube tray and freeze into small manageable sections so you can use as and when required.
If freezing your blood is not an option (and let’s face it many family members might object to you using the household freezer to store menstrual blood) then you can store neat drops of the blood in oil or alcohol to act as a preservative. These can be sealed in small bottles and kept in a dark cupboard until use.
Another option is to saturate a tissue with the blood, dry it out and then store it in a jar where pieces can be ripped off for use when required.
For witches who prefer to use sanitary towels or tampons the procedure can be a little messier. Place the used sanitary item into a bowl of warm water and agitate gently. Once soaked through wring the item out to squeeze as much blood as you can from it into the water. Discard the item and then the diluted blood water can be frozen or stored in a jar. Be aware that the problem with this is that you are using diluted blood which may not suit your purpose. I’d also caution that this is by far the least pleasant smelling method of storing menstrual blood. A month or so in a jar (no matter how tightly sealed) will smell pretty strong when you open it. Refrigerating it will increase the longevity but again you have the problem that family members may not like your blood on the shelf next to the milk.