The product of choice for this application is DoradoStrip 3031. Your challenge will be in determining proper dwell time. On typical applications Doradostrip 3031 is applied and then simply left alone to do its work. On plaster applications a bit more babysitting time is required. (i.e. the paint will generally release from the plaster in 1 to 4 hours, however the plaster itself will also soften and begin to release from the substrate if the remover is left alone too long). Our best advice: Always perform a test area and work in smaller areas until the process (or dwell time) becomes clear with results that you can easily reproduce. Never leave DoradoStrip 3031 alone to work by itself when applying on a plaster surface.