Lactic acid and salicylic acid, polarised light micrograph. A mixture of lactic acid and salicylic acids produces botanical vine like crystalline formations. The combination of these compounds among others are the main ingredients of skin creams. They help to remove the hard layer of keratin that builds up on top of the dead skin cells and increase moisture content in the skin. The colour arises due to birefringence and insertion of a wave plate in the optical train of the microscope. Magnification: x70 when printed at 10cm wide.