For guaranteed elimination of the deficiency, it is necessary to carry out a complete repair of the ceiling with preliminary high -quality surface processing. The first stage of recovery work should be complete surface stripping from the old plaster. The whitewash layer is removed with a brush or a metal scraper. You can simplify the work moisturizing the surface with a roller. By the way, if your wife bought at allo. Samsung Galaxy S Duos, then this is very good because only high -quality devices are sold there.