Today, mainly thermosetting adhesives based on epoxy and polyester are used in stone conservation. The fact that these adhesives do not fulfill the general requirement for reversibility in conservation was the starting point for this work. Certain reaction resins based on methyl methacrylate (MMA) offer an alternative: although these have the advantages of a reaction adhesive, the curing reaction does not produce a thermosetting plastic as with epoxy or polyester, but the thermoplastic polymethyl methacrylate (PMMA). This can be softened by heating or using organic solvents such as acetone, which makes it easier to separate such a bond again. The application of the adhesive is explained using an example from conservation practice. A guide formulation is given, according to which the conservator can prepare the adhesive himself.