Whenever I want to clean walls or remove stains I use sugar soap (diluted) and some warm water (keep well away from children). I find on my walls it is gentle and effective. Whatever is used it is always recommended to try on a small bit of wall and then see how it looks and if it is effective. Might also be a good idea to do some google searches on this issue. Home maintenance and cleaning sites might be useful? Good Luck!
Published 21st October 2019