Windows should be washed twice a year. Instead of using spray cleaner, squeeze a drop of dish-washing liquid into a bucket of warm water. Use window washing tools like a strip applicator or a squeegee for best results.
A strip applicator has a long soft head to easily apply soapy water and remove dirt from windows without scratching. After applying soap and water, pull a squeegee over the soapy window using an S-shaped stroke. After each stroke, wipe the excess soap from the squeegee blade with a soft rag. Use a moist chamois to clean up any leftover moisture on the glass. Wipe the sills with a cloth.