Shadow Mask, Cromaclear
Both CRTs are more resistant against vibrations because of the hole metalsheet - but cannot perform the contrast
and brilliance of an 'aperture grille'. Moreover they tend to 'Dooming', caused by heating through the electron beam. The
heating deforms the mask and makes the electron beam impossible to correctly pass the shadow mask. Thereby arise
colour purity and brightness problems, especially in the corners of the screen.