When the solid has a high affinity for water - in which case it is called hydrophilic (high energy e.g. glass)- water spreads. In the opposite case of hydrophobic (low energy e.g. teflon) surfaces, water does not spread but, instead, forms at equilibrium a spherical cap resting on the substrate with a 'contact angle'.
Infections such as trichomoniasis, gonorrhea, and Chlamydia (all STDs); and yeast infection can all cause vaginal discharge. Vaginal discharge can be associated with other symptoms such as burning or itching. Antibiotics are given for infections that cause vaginal discharge.
If you have bacterial vaginosis, yeast (Candida), trichomoniasis or any other sexually transmitted infection you want to know as soon as possible. Familiarizing yourself with the characteristics of your vaginal discharge on any given day can help you know when things are not right. So wash your hands, give yourself some good light and explore. Color. If discharge is clear or milky white, that's normal. It can also look very pale yellow when it's dried. If you are seeing grey, green, yellow, pink or red, that's not. Blood-tinged mucous may be a sign of pregnancy.