Poor Drywall Corner bead is very cheap, and it breaks after being folded twice. The production process is clay crucible drawing, and the glass fiber is usually made of waste glass from some beer bottles.
It is a production process prohibited by the state, and the surface coating is not alkali-resistant emulsion. From an intuitive point of view: the workmanship is relatively rough, generally sold more in the market, often lacking in length, easy to shift, and easy to pierce the skin.
This type of drywall return bead is used in poor insulation quality. The joint is not firm. The layer generally loses its strength after two months. If the mortar is knocked off and the drywall return bead is taken out, as long as it is gently rolled, the glass fiber yarn will become powder.
There is also a kind of bullnose corner cap. But sometimes it is difficult to judge the authenticity, and its quality can never meet the requirements of the exterior wall insulation with a real alkali-resistant cracked corner bead from the outside.
The fiber diameter is relatively thin, and the glass is selected through the plate broken glass, also called mixed silk yarn. This is a kind of imitation, often some flat glass fibers with good transparency.