Odorless and no unhealthy vapours. A good alternative to Vitrex. An excellent option in particular for people who work without extraction / from home. Under current legislation (REACH/CLP), alum, as we sell it, is not classified as a hazardous substance. It is not aggressive, so it works slightly slower compared to vitrex (about 2x as long).
The ratio that is often used is 1 to 15 (33 grams to half a liter)