When working with brake fluid, remember the following:
Brake fluid must be stored in such a way as to prevent accidental access to it.
Brake fluid is corrosive to metal, so contact with painted surfaces should be avoided. Spilled brake fluid must be washed off immediately with plenty of water.
Brake fluid is hygroscopic, i.e. has the ability to absorb moisture from the air. For this reason, it should be stored in an airtight container.
Brake fluid cannot be reused. Even when bleeding the brake system, always use fresh brake fluid.
DOT 4 brake fluid specification.
Care must be taken to ensure that the brake fluid does not come into contact with mineral oil, as even slight traces of oil in the brake fluid make it useless and lead to failure of the brake system.