Magnesia boards have different properties depending on their quality. The first is the magnesium oxychloride board produced by magnesium oxide and magnesium chloride. Low-quality boards will produce water droplets when the temperature difference is large and the humidity is high, and the paint you apply will naturally fall off. If the quality is higher, you can apply oil stains, putty and other coatings. The second type is magnesium oxide and magnesium sulfate products. Although they will not produce water droplets, low-quality magnesium sulfate boards have poor strength and are easy to break. And if the flatness is not enough, then the paint on the picture is also a waste