Wet weather = mould! I recently cleaned our venetian blinds and was shocked at the spores of mould on them. I had only just cleaned them two months ago. This time, after cleaning them, slat by slat, I liberally sprayed them with Tea Tree Liquid Spray, not only will they resist future mould, they smell fabulous. I also topped up my ever present tub of gel and hey presto, I'm good to go.