Neon colors are created from special neon pigments, so they cannot be created by mixing basic colors. Oil paints are made only in basic colors. Unlike acrylic, there are no fluorescent or neon colors in oil paints. Still, there are methods and techniques for oil painters to achieve the effects of neon, including brilliance and sparkle.
Transparent Colors From the Tube
Use transparent colors directly from the tube, when possible. When oil paints are squeezed directly from the tube, they are highest in saturation and brilliance, which are necessary to achieve neon effects. Liberally use paints directly from the tube, since skimping will thin the paint and reduce brilliance.
Mix colors as minimally as possible to preserve brilliance, as the more a paint is mixed, the duller it becomes. In particular, avoid mixing transparent colors with an opaque color, including white, since a transparent color mixed with an opaque color results in an opaque color. Also, dip the brush in turpentine to remove residual paint, especially browns and other opaque colors, before using to transfer transparent colors to the canvas.
Lighten color by mixing with pure zinc white, which is more transparent than titanium white, the color most commonly used to lighten colors from the tube. Use only a tiny dab of pure white zinc, so as not to interfere with the brilliance of the tube color.
Tools and Technique for Mixing
Mix colors with a palette knife, rather than with your brush. Your brush has residue of colors that may contaminate the mixture of paints. Mix colors on the canvas, instead of the palette, as mixing colors on the canvas creates a more sparkling and brilliant effect.
Emphasize neon effects on the canvas by contrasting them with mixed opaque colors. For instance, if painting a neon sign, surround the sign with muddied and opaque colors, whether light or dark. This will make your bright neon colors stand out.