Oil Paint- Oil-based paint that contains oil as the basic vehicle ingredient. Oil paint can be designed for interior or exterior use. It must be thinned and cleaned up with solvent. Pure oil-based paints have largely been replaced by alkyd paints.

Oleoresinous- Film former containing oil and resin.

Opacity- The ability of a paint to hide the previous surface.

Opaque Coating- A coating that hides the previous surface.

Open-Time- The amount of time a glaze or paint stays wet and workable for desired finish.

Orange Peel- Film having the roughness of an orange due to poor roller or spray application.

Organic- Containing carbon.

Organosol- Film former containing resin plasticizer and solvent; colloidal dispersion of a resin in plasticizer containing more than five% volatile content.

Orifice- Opening; hole.

Osmosis- Transfer of liquid through a paint film or other membrane.

Osmotic Blistering- Formation of blisters containing liquid.

Overcoat- Second coat; top coat.

Oxidation- Combination with oxygen; drying; burning; rusting.