It is a 5% solution of Paraloid B-72 used by professionals for safekeeping of finds.
The main reason for this is that paraloid B72 is transparent, not brittle, very durable and stable. It does not yellow and is easy to process. The material is completely reversible. It is always soluble and completely removable by re-dissolving it in a solvent such as Acetone.
The synthetic resin is dissolved in a solvent. Solvents can be harmful. Always wear protective clothing, gloves and goggles. Use only in a well-ventilated area or outdoors. Read the instructions for use and the safety data sheet before use.