Look: Look at the appearance of oil products. In general, different types of oils have different color appearances. When identifying, the color and size of the oil container are required to be the same, otherwise it has a great influence on the result of the observation and judgment. Carefully observe the appearance color of oil products. The light colors are mostly light-distillate and deep-refined oil products; deep-colored oils are mostly residual oils, low-purity oils, or heavy distillate oils. Smell: smell the smell of oil products. The smell of oil is generally divided into gasoline, kerosene, diesel, alcohol, aromatic, sour, and so on. The oil added with additives has a certain sourness; the oil with alcohol composition has alcohol taste; the light solvent oil has aromatic flavor. Shake: Observe how thick the oil is after shaking. By shaking the oil in a colorless glass bottle and observing the phenomenon of oil film hanging and the occurrence and disappearance of air bubbles, different grades of oil can be basically distinguished. Small viscosity oils have more bubbles, faster rise speeds, and disappear faster, with less hanging bottles; oils with large viscosity produce less bubbles, slower rising speeds, and slower disappearance, but more oil hanging bottles. Touch: Touch the hard and soft conditions and smoothness of the oil. The refined oil hand feels smooth and smooth; poorly refined oil has a poor smooth feel. The degree of hardness and hardness can be divided into different grades. The smaller ones are softer; the larger ones are harder. Hair Removal Machine,Hair Removal Device,Best Hair Removal Device,Laser Hair Removal Device Shenzhen Jie Zhong Lian Investment Co., Ltd. , https://www.szmeizon.com