Do you know the difference between primer and paint? Is it possible to paint without primer? What kind of primer should you use on which kinds of surfaces?
To prime or not to prime is a subject that confuses most novice arts and crafts enthusiasts. Many often make the mistake of skipping the priming step, moving ahead to painting on a bare surface. Unfortunately, that can lead to a lot of grief as the project nears completion. It can even present problems during the life of the painted subject.
Don’t make the mistake of skipping the priming step. Primer is an indispensable asset when painting wood, metal and especially plastic objects. It’s chemically designed to act as a “beachhead” on the surface of the object to be painted, helping the paint to adhere while also keeping it smooth and durable. Priming even protects the painting subject from many kinds of damaging decay.
So what is primer, exactly?
Primer is a kind of paint that’s chemically mixed to bind to its subject material. It’s designed as an undercoat, meaning it’s not required to offer durability or shine like normal paints. It’s sold in both liquid and spray-can forms.
Because it’s an undercoat, primer is engineered to aggressively stick to its subject material, forming an intermediary between its surface and the layers of paint to be used atop it. In some cases, such as with many kinds of plastics, primer will also help slow the growth of mildew as years go by. Priming also helps prevent moisture damage and mildew on wood, gypsum board, and other porous surfaces.
Priming wood is mandatory. Bare wood will soak up solvents from paint directly applied to it, shortening the life expectancy of the paint. Bare wood surfaces will also cause the pigment of the paint – and by extension the shade or hue visible to the eye – to alter in response to its own coloring. Finally, priming will also eliminate dry rot and warping of the wood itself.
Plastics should be primed in order to “reset” a subject object’s color. As with wood, this means the primer will prevent the color of the underlying object from “seeping” through or altering the paint applied atop it. Priming also reduces the number of coats needed to obscure the original color.
Priming plastics works best when the object is small enough to be primed with spray paint.
Only some metals, such as aluminum, need priming as a means of preventing rust. Priming in many cases will also prevent flaking of the paint from the metal later on.
Experts recommend priming metal especially when working with aircraft or parts that will be exposed to atmospheric conditions.
Spray primer is typically sold in white and gray colorings. Gray primer will give the colors applied atop it a slightly darker hue than white primer.
Primer, whether liquid or spray, should be applied much like conventional paint. Painters should apply the primer outside, using all safety precautions regarding breathing, in a low humidity area. Spray primers typically dry in thirty minutes or less. More than one coat may be necessary, applying until the object is completely and evenly painted with a consistent coat.