Always wash ground glass and fresnels with your finger tips only rubbing the fresnel in the direction of the ribs only. I use Dawn dish soap. I spray mildewed bellows with Lysol Disinfectant Spray on the inside after washing the outside down with Isopropyl Alcohol. Treat the outside of the bellows with Pledge Furniture Polish in the yellow spray can as a final step. The bees wax and lemon oil is good for vinyl and leather.