How do you preserve milk powder and soap powder?

To preserve milk powder, store it in a cool, dry place in an airtight container to prevent moisture absorption and clumping. It's best to use it within the recommended shelf life, typically 1-2 years, and check for any off odors or discoloration before use. For soap powder, keep it in a sealed container away from humidity and direct sunlight, as moisture can cause it to clump and lose effectiveness. Always follow the manufacturer's guidelines for storage duration and conditions.