Before using defoamer, it should be tested first, otherwise it will not achieve the ideal effect due to improper selection, or even produce certain harm. We can test the performance of defoamer qualitatively or quantitatively according to the actual needs. What are the specific methods of defoamer test? Here are some examples.           
1、 Measuring cylinder method. The simplest and most common method is the measuring cylinder test. In the 100ml measuring cylinder, 50ml foaming solution is added. Each time the bottle is flutked 20 times up and down, the foam height and defoaming time are observed.           
2、 Spray test: spray bubble solution to make bubbles, then add defoamer to determine defoaming effect according to defoaming time.           
3. Circulation pump test: put bubble solution in closed loop flow, add defoamer to agitator, and measure foam height. The method is based on the quantitative evaluation of the anti foaming performance under the dynamic state of stirring, emulsification and shearing. When the solution circulated in the closed loop, the time needed to achieve a certain bubble height is measured to evaluate the defoaming efficiency.           
4、 Densitometer measurement: use densitometer to measure the density of foam liquid mixture. The difference between the density value and the density of foam liquid before mixing represents the foaming amount. The larger the density difference is, the higher the air content in the foam liquid mixture is, the greater the foaming force is. The percentage of density difference in the density of foam liquid before mixing represents the foaming rate. Test the foaming amount of the slurry after adding the defoamer and the foaming amount of the blank slurry The difference between the amount of antifoam and that of the blank pulp is the amount of antifoam.