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.
Yellow vaginal discharge can be a symptom of several conditions and diseases. Several factors can cause vaginal discharge that is yellow in color, thick and bears a foul odor. Some women can get such yellow discharge before period, while others can get it after period. Yellow vaginal discharge could be associated with vaginitis, cervicitis and/or sexually transmitted diases (STDs).