Paint primer is a “glue” like substance that adheres itself to walls before a coat of paint to help make the walls easier to paint. Primer serves not only to hide previously dark paint, mold, dirt, or drywall putty, but can also help you smooth out the entire wall to give a uniform painting surface to apply a fresh coat to.
When is Priming Necessary?
Paint primer is a “glue” like substance that adheres itself to walls before a coat of paint to help make the walls easier to paint. Primer serves not only to hide previously dark paint, mold, dirt, or drywall putty, but can also help you smooth out the entire wall to give a uniform painting surface to apply a fresh coat to.
Which Primer is Best for My Job?
Unfortunately, there are often an overwhelmingly large number of paint primers to choose from and many first-time painters are unsure of which primer is best.
Luckily, primers can be broken into three basic categories: hiding raw materials like drywall, hiding underlying colours, or hiding stains. While you may have to get an additional primer for painting doors or trim, these three basic undercoats should mask just about anything hiding beneath the surface. Each primer is designed to flatten the drywall or plaster surface or spread on thick to hide old colours or stains.
If you are painting over existing paint, know that if a the previous paint was oil-based and glossy, you will need to use a ‘bonding primer’ instead of a traditional water-based primer to get the job done. Water-based paints will not stick to a previously glossy wall.
Regardless of what was underneath before, it’s worth noting that if you would like to paint a room a dark colour, you should use a tinted primer instead of a standard white. Tinted primers prevent the dark colour from bleeding into the existing paint or drywall.
How to Apply Your Primer
First, cover all door and window frames with painter’s tape to prevent accidental colourings and use a putty knife to press the edges of the tape into the cracks.
Primer should be applied just like paint, with large fluid brush or roller strokes across the entire wall. Always start painting or priming in the middle of the wall to prevent large amounts of paint from gathering in the corners or near trim. Also, don’t overfill your roller or brush with primer before starting. A common amateur mistake is to overfill the roller or brush and have paint drip down the walls because you aren’t able to move it around quickly enough.
You should also make sure to finish entire walls at a time. Because drying paint tends to blend together, finishing just trim first and coming back later to paint the large sections of the wall will lead to an uneven drying pattern.
Some painting professionals also employ what’s known as “spot-priming.” This technique applies a small amount of primer only to areas of the walls that may shine through to the new top coat. Stains or mold can be spot-primed so that the entire wall doesn’t need to have an expensive priming coat added.
