Total Immersion Testing

Specimen Preparation

Technicians cut the plastic sample to a precise surface area before placing it in the test tube filled with the chosen simulant. Glass spacers are often used to prevent multiple specimens from sticking together during the test run. This maintains the exposed surface area at a known and constant value.

Extraction Calculation

After the heating cycle, the concentration of the migrated substances in the simulant is measured and calculated relative to the total surface area of the plastic sample. This value is compared directly with the regulatory specific migration limit to determine compliance. It provides a conservative measure of migration since both sides of the plastic are exposed.

Method Limitation

This technique is not suitable for multilayer materials where only the inner layer is intended for food contact. Submerging the entire sample would allow extraction from the outer layers, leading to false high migration results.