BPO 50% paste, also known as hardener, is a uniform dispersion of dibenzoyl peroxide in a smooth, non-separating fire resistant creamy paste form, which can be easily dissolved in monomers and resins. It is soluble in ethyl acetate and slightly soluble in petroleum solvents and alcohols and also insoluble in chlorinated solvents. This product is easier to use and less hazardous than dry forms of dibenzoyl peroxide.