I am writing my bachelor thesis about alternative materials for feminine hygiene products and for testing I need to know what the viscosity is of menstruation blood. Can I use water as replacement for menstruation blood because this kind of blood exists out of a big part of water? And what is the composition of menstruation blood in percentages?
It is difficult to give a typical value as the composition and hence the physical properties of menstrual blood varies over the course of a woman's period. This reference has a good discussion which you may find useful; you can find on p. 159:
It is fair to say that a large proportion of menses samples are considerably more viscous than blood or water - about four times as viscous as venous blood and 35 times as viscous as water.