If Heinz made window cleaning equipment. ?Think a lot depends on rubbers, sqeegee and technique ,in past i have used washing up liquids and window cleaning soaps . At the moment using a pressurized hand pump connected to wagtail with moerman channel fitted with syr rubber with fliq . 1 litre of water with 5ml GG£ and 1ml of added sparkle works a dream for me and last all day my need top up if really hot day.