I recently purchased some cheap silicone ice cube trays from Aliexpress. After the first use, I noticed a fatty residue floating on top of my drink. Research suggested it might be lime scale or minerals from hard water. Many websites claim it's calcium sulfate. However, my preliminary tests contradict this theory.
Experimental Evidence
- Control Test: I used a plastic ice cube tray with the same water, and no residue appeared.
- Vinegar Test: Adding vinegar to an ice cube didn't dissolve the residue.
- Hot soap wash: Boiling the ice cube trays in water with dish detergent did not fix the problem. Its unlikely to be the release agent that is ending up in my drink.
Hypothesis I believe the residue is more likely caused by a silicone additive leaching into the ice cubes. I also noticed a white film forming on the outside of the ice cube tray which feels waxy when rubbed between the finger tips. Can mineral pass through a thick layer of silicone?
Request for Help Chemists, please help! What tests can I conduct to identify the source of this residue? Are there any specific chemicals I can use to determine the composition of the residue?
