In a general way, it is divided into the special magnesium oxide used in taped and directly used. The magnesium oxide used in taped has characteristics of large volume, good dispersibility and moderate activity. It will be better when the specific volume is between 80 and 120. The magnesium oxide directly used requires the activity is between 120 and 150, the specific volume is about 5. These two magnesium oxide all asked the lower content of calcium and iron.
Common qualitative questions:
The low content of magnesium oxide easily generates white suspended solids. The excessive content of calcium, poor activity and not enough fineness will bring sediment and layering phenomenon. If there is a thick white sediment at the bottom of the adhesive container, it belongs to normal phenomenon. If there is more white sediment, it is abnormal phenomena. Maybe, it is the problem from magnesium oxide, or the talcum powder of chloroprene rubber adhesive. If there is too much white sediment, it is not the problem from magnesium oxide. Maybe, it is the problem from resin or solvent. The high content of iron leads to the glue become red. Generally speaking, the content of iron can not higher than 0.05(The best is lower than 0.03). It is the problem from magnesium oxide or chloroprene rubber adhesive if it become slightly red or pink. When it becomes to dull-red, deep red or the color like hog blood, it reflects the solvent or resin has problems, but not the magnesium oxide.