Polyurethane black material (isocyanate component) reacts, crystallizes and solidifies when it meets water or moisture.

In the barrel containing black substances, there will be some black substance crystals at the bottom of the barrel, and a small amount will adhere to the barrel wall.

The effect of common solvents such as butanone and acetone in dissolving black substance crystals is not ideal. We usually use dimethylformamide (DMF) to dissolve the cured polyurethane black material. After soaking in it, the surface layer of the crystal will melt and soften. After cleaning the soft layer, it will be soaked in DMF until it is completely dissolved.

If the crystalline layer is too thick, the problem can generally be solved by tapping or punching vibration method combined with solvent method. Not the same as 2.

Cyanate ester (commonly known as black material) and combined polyether (commonly known as white material) must be stored in a sealed container, isolated from the air to prevent moisture absorption. Barrels of isocyanate (black material) and combined polyether (white material) cannot be exposed to the sun, and must be kept away from heat sources and placed in a cool and dry place. If the bucket stands upright, there should be no water on the lid. If the whole barrel cannot be used up at one time, the barrel cover must be covered immediately after each use to prevent water vapor and impurities from entering the barrel and affecting the quality. If two or more brands of combined polyether are used, they should be stacked according to the brands and clearly marked. The combined polyether of common flame retardant should not be stored for too long and must be used on the day of preparation, otherwise it will easily lead to deterioration and affect the foaming quality.