Flexibility

Gentoo's flexibility was assessed using standard mandrel bend testing at room temperature and at low temperature (-51°C), and its thermal stability was characterised by thermogravimetric analysis (TGA). Together, these tests establish the operational temperature range and mechanical flexibility of the Gentoo coating system.

Mandrel Bend Testing — ASTM D522

Initial flexibility assessment was performed using a mandrel bend test in which coated metal coupons are bent around mandrels ranging in diameter from 1/8 inch to 1 inch and evaluated for cracking or delamination from the substrate, per ASTM D522. Cold temperature flexibility was assessed per MIL-PRF-85285, bending Gentoo-coated panels over a mandrel at -51°C.

Room Temperature Results

Gentoo demonstrates excellent flexibility at room temperature. On both direct-to-metal substrates and on panels coated with MIL-PRF-85285 grey urethane topcoat, Gentoo passed the ¼ inch mandrel bend without cracking or delamination. The underlying paint system showed hairline cracking at the smaller mandrel diameter, but the Gentoo film itself did not crack — indicating that the sol-gel coating has superior flexibility relative to the polyurethane topcoat it was applied over.

Low Temperature Results (-51°C)

At -51°C, Gentoo-coated panels with MIL-PRF-85285 grey urethane topcoat were bent over a ¾ inch mandrel. Cracking occurred, but investigation confirmed that failure originated at the primer-to-aluminium panel interface — not within the Gentoo film itself. The ragged failure edges observed were consistent with Gentoo attempting to maintain coating system cohesion despite the underlying substrate delamination. An aluminium panel coated with Gentoo alone (no primer) was re-evaluated at -51°C and passed the ½ inch mandrel bend. Hydrophobic performance of the Gentoo film was retained on the tested surface following cold temperature flexure.