Appearance in places of gloss on external surfaces, which over time shows black vertical stains.
In repairs, which are mainly wrong repair of cracks, losses (of) acrylic “mastic” or elastic putty and transparent primer before the final paint. Over time, mastic plasticizes the color (ie softens it in these areas) and increases its gloss (increasing adhesion). At the same time in this area the color becomes more waterproof, with the consequence that the rain does not wash away the blackheads from the air pollutants.mounted on the masonry. Instead it forms droplets, which join in a vertical imaginary line carrying the blacks. When the surface dries, the black lines, like black vertical runs.
For the repair of cracks, it is recommended to use the elastic putty with pellets, without the need for primer. Due to the composition of this putty, the surfaces do not appear in places glossy and black runs.