Light Stabilizers - HALS HALS are radical scavengers that trap radicals formed in the coating or sealant layer during exposure to light and heat. HALS additives are particularly suitable for the surface of product, where UVAs offer less protection. Moreover, HALS stabilizers provide protection against surface defects such as cracking and water permeability. The cyclic nature of the stabilization mechanism of HALS means that they typically show higher and longer term protection compared to other stabilizer additives.