Do I Need to Prime a Wall Before I Paint It?
When saving money is the goal of a do-it-yourself painting project, each expense needs to be carefully considered. Before starting a painting project, a common question for homeowners is if they need to prime a wall before painting it.
The simple answer is that primer is not always necessary, so it’s possible to save money by omitting it. However, in many cases primer will actually save you money because it reduces the number of more expensive topcoats you will need to get beautiful, lasting results.
Lions Head Painting suggests using primers before painting in the following circumstances:
New Drywall & Skim Coating
The process of drywall installation and/or skim coating leaves a great deal of highly absorbent space to paint, and it may require many coats of high quality paint to give adequate coverage. Use a coat or two of quality primer first, however, and the pores will be sealed and your new topcoat will cover nicely in one or two coats.
Patched or Repaired Drywall
If you have repaired a wall before painting, you will likely have patches of spackle or joint compound on the surface. If these repairs are small, you do not need to buy a separate primer; simply use a small amount of your regular paint and brush it lightly on those areas to “spot-prime” the wall. Then, when these spots are dry, you can paint the wall normally and those spots will not show through.
Major Change in Wall Color
Painting contractors generally assume that a dark color will cover over a light color very effectively with one or two coats. Light paints, however, will rarely cover dark colors even with many coats. In order to save money and time, professional painters recommend using a good primer with strong “hide” qualities.
Painting over Oil-based or Glossy Paints
In order for the new paint to perform well, the new paint must have a surface it can adhere to. When the current layer is oil-based or has a sheen, this surface can be achieved in two ways. You can use sandpaper or TSP to scuff up the surface, or you can apply a bonding primer which will stick straight to the underlayer and provide a good backing for the new paint. If you need to prime anyways because of color change, then use this method and skip the sanding. If you don’t need to prime anyways, however, it will probably be cheaper and faster just to do the scrubbing.
Stain or Odor Coverage
Some stains, such as greasy spots or crayon scribbles, will show through new paint. Also, cigarette smoke and other strong odors can still be detected after repainting. In order to truly block out the ghosts of these issues, painting contractors use a serious primer like Kilz or Zinsser. Note: do not use a primer to hide mold or mildew in your walls. It will only grow. Instead, first deal with the cause of the mold (usually water entry), and remove the mold. Then, you are free to prime and paint.
Many professional painters use a tinted primer before painting. This is an inexpensive way to bring your walls close to their final intended color before adding the more pricey topcoat. Ask about this at your paint store if you are painting a bold or dark color.