With excessive temperatures or excessive air speed in the spray booth, with the spray gun at an insufficient distance from the work piece, with insufficiently ventilated hydrogen peroxide as a characteristic of the material. In the event of doubt, spray the lacquer in question onto a glass plate. Where the lacquer dries on the neutral glass without forming bubbles, the cause is to be found with the spraying, in the spraying area or with items being worked on whose temperature is not reduced or where they are insufficiently ventilated. With wood, bubbles can also be due to air escaping from the pores or the grain being too course. Bubbles can also form with veneered chipboard where the adhesive has not set sufficiently