Parts produced over a single sided mold have an A-side and a B-side. The A-side does not come into contact with the tool and so has a higher surface finish than the B-side. Processes that use a single sided mold include composite laminating, superforming and thermoforming.
A-side, or anodising, is an electrolytic passivation process used to increase the thickness and density of the natural oxide layer on the surface of metal parts. This process is of no use on carbon steel because rust puffs up and flakes off, constantly exposing new metal to corrosion. But on many other metals, A-side increases corrosion resistance and wear resistance, and provides better adhesion for paint primers and glues than bare metal. Anodic films can also be used for a number of cosmetic effects, either with thick porous coatings that can absorb dyes or with thin transparent coatings that add interference effects to reflected light. Anodization changes the microscopic texture of the surface and can change the crystal structure of the metal near the surface. Coatings are often porous, thick ones inevitably so, so a sealing process is often used to improve corrosion resistance. The process derives its name from the fact that the part to be treated forms the anode portion of an electrical circuit in this electrolytic process. A-side can prevent galling of threaded components. Anodic films are generally much stronger and more adherent than most paints and platings, making them less likely to crack and peel. Anodic films are most commonly applied to protect aluminium alloys, although processes also exist for titanium, zinc, magnesium, and niobium.