What do you use in your water?

This is the most common question I get.

For external glass surfaces which haven’t been washed for years, or which have a lot of debris such as bug droppings, I use a mixture of a detergent plus ammonia, otherwise just detergent.
For internal surfaces, it’s usually window-cleaning detergent, unless the client/tenant has an allergy to chemicals, in which case I use a special detergent made from organics.

Why detergent?
Detergents provide two valuable qualities for cleaning windows – they lift water-soluble dirt from the glass into suspension and lower the friction of a squeegee on the glass surface.

So, which detergent?
Window cleaners are split between using household dishwashing detergents and special detergents made for window cleaning.
Those against using detergents such as Dawn, Fairy, Palmolive etc, claim these detergents as well as being too sudsy, contain perfumes, colourings and other non-essentials.