Inappropriate application, in the exterior, of interior reparation dough. Dust that was not previously removed. Repainting over a poor quality paint, in which the humidity of the new paint permeates in the old paint, causing bubbles. On the elastic membranes, when poorly used, or when there are water infiltrations in the wall, this problem is common to appear. POSSIBLE REPAIRS
Scrape off existent repair dough and apply some new adequate dough to repair the surface in order to paint after drying. Sand all the surface to remove the old paint. Apply the adequate primer and apply the finishing. Sand only the affected areas, properly eliminating dust, apply an insulating and the finishing paint. Eliminate existing moisture and infiltration, repairing de cause of this problem. Allow to dry, sand, remove dust and finally proceed to paint.