Airframe 8083 - CH 8: Aircraft Painting and Finishing

Solvent

A chemical that is added into other liquids in order to thin the liquid, making it sprayable. Solvents must be volatile, and will cool the surface that it is applied onto once it evaporates. Think about sweating and how it cools your body. Due to their volatility, these are one of the many chemicals you want to avoid inhaling.

Acetone

A highly flammable, volatile, clear solvent, used for removing grease from fabric before doping, and most often used for paint thinning. It can also be used for varnish removal. Ideally this would be used for thinning fiberglass resin, polyester resins, vinyl, and adhesives.

Methyl Ethyl Ketone (MEK)

A highly flammable, volatile, clear solvent, that is ideal for varnish removal, paint and primer thinning, in surface coatings, adhesives, printing inks, polyester wax catalyst, and resins. MEK is effective at reducing emissions during coating operations due to its volatility. Wear gloves while applying. Overall, a really versatile solvent.

Methylene Chloride

An extremely effective paint stripping solvent. This is the more dangerous, not so environmentally friendly stripper. Also great for degreasing/cleaning metal parts. Despite its danger, its flash point is actually very low under normal use conditions, so it can be used to reduce the flammability of other substances.

Toluene

A clear, water insoluble liquid with a distinct benzine-like odor. Commonly used in paints, paint thinners, lacquers, and adhesives. Acceptable thinner for zinc chromate primer. Toluene is likely linked to brain damage, so respirators and PPE is priority.

Linseed Oil

The most common liquid carrier in oil paint. It makes the paint more fluid, transparent, and glossy. Makes brushing easier, and provides a better final product. Linseed oil is more subject to spontaneous combustion, so disposal of soaked rags must be done carefully and diligently.

Thinners

A plethora of solvents used to reduce the viscosity of any primers, subcoats, and topcoats.

Varnish

A transparent protective finish for wood. Viable for interior and exterior grades, however the exterior grade will not dry as hard as the interior to allow for thermal expansion without damaging the finish. Commonly is a combination of a drying oil, a resin, and a thinner or solvent. Polyurethane and epoxy varnishes will remain liquid after the solvent evaporates, while resin varnishes will harden once it evaporates.

Primers

A primer is the foundation for the final topcoat finish. Its bonds to the surface, inhibits corrosion of metal, and provides an anchor point for the finish coats. The primer pigments must be either anodic to the metal surface or passivate the surface (should moisture be present). The binder MUST be compatible with the finish coats or else the finish could peel/be unsatisfactory.