When Should You Use a Primer?

Prime Walls

You may not be familiar with primers, however there are many painting applications where using primer is not just optional, but mandatory for creating a beautiful finished project.

Primer’s purpose is to:

  • Provides a uniform and attractive paint finish.
  • Blocks tannin, water, grease and smoke stains that can bleed through your topcoat.
  • Improves adhesion of the topcoat 

How do you decide whether or not to use a primer? Much will depend on the existing surface that you are painting, the color of the surface, how dark the paint is that you are applying, and whether or not the surface is porous or has any water damage. Here are some tips for deciding if you should use a primer when painting. 

It is always a good idea to use a primer regardless of the paint job you are tackling. Primers help the paint to go on uniformly and create a beautiful finished project. In the circumstances mentioned below, primer is a necessity, not an option. Always be sure to analyze your painting project before you begin to decide whether using a primer will be in your best interest or not. 

Primer Selection:

New wood – If your wood isn’t seriously stained, use a high-quality latex primer or an oil-based primer. If you have wood that is stained or you are painting redwood or cedar, use a stain-blocking primer. 

Painted wood – If your paint is in very good condition, a primer may not be needed. However, if you have exposed wood, chalking or chipped paint, use an oil-based primer. Before you prime, scrape away as much chipped paint as possible and wash off any chalk. (Just because you are using a primer doesn’t mean you get to skip surface preparation.)

Weathered Wood – Use a high-quality latex or oil-based primer. Sand and scrape away as much paint as possible. When you start to see new wood fibers, start priming. 

Masonry Fill a fresh surface with block filler before painting. If repainting, scrape off any loose or peeling paint and cover with latex paint. Use a block filler only if the paint has been completely scraped off.

Aluminum and Galvanized Steel – If your surface is rusty, remove the rust and apply a latex or oil-based, corrosion-resistant primer. If the surface is new and rust-free, you can apply a high-quality latex paint and no primer.

Drywall – Use a latex primer. Don’t use an oil-based primer unless you are putting up wallpaper or covering a stain. Oil-based primers raise the grain of the drywall and make the finish look uneven.

Stains – Crayons, water, smoke and grease can bleed through the topcoat. Prime these areas with a stain-blocking or stain-killing primer. Oil-based stain killers work the best on water stains and for spot priming. Latex stain-blocking primers work better on large areas and hold up better on exterior surfaces. Pigmented shellac primer works well to block smoke and soot damage as well as to block animal urine smells and graffiti. 

Dark Colors – If you are painting over a dark color with a much lighter color, you can use a high-hide latex primer to reduce the number of top coats required to hide the existing color.

Light Colors – If you are painting a dark color over very light walls, you can use a general latex primer tinted to the color of your top coat to help reduce the number of top coats required.

Shiny surfaces – Bonding primers will stick to glass, tile, Formica and previously painted surfaces. Use bonding primers for interior surfaces only. They tend to crack when exposed to the elements because they aren’t flexible.

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