Most painters know that one of the keys to a good paint job is priming but understanding all the ins and out of primer — from what and when to prime, to choosing the right product for the job — can be a challenge.
Primer is a coating applied to substrates before painting that ensures better paint adhesion and increases paint durability. They are actually less like paint and more like glue, since they stick to whatever you’re preparing and seal the substrate to ensure a good finish that will last for years.
There are two types of priming (1) spot priming is for small patch areas and minor spaces where peeled paint has been removed and (2) complete priming for large, bare areas or surfaces that may have dark colors or an uneven sheen. There are different primers for drywall, plaster, metal and woodwork, to properly seal the surface so your finish paint adheres and dries smoothly and uniformly.
When it comes to painting exteriors, primer is almost always needed, as these surfaces are constantly subjected to harsh conditions, such as moisture and UV rays. This kind of exposure causes surface deterioration, which makes paint adhesion a challenge. Besides providing good adhesion, primers are designed to deal specifically with common conditions such as efflorescence on masonry or tannin staining on cedar and redwoods.
Here are specific uses from the experts at Dunn Edwards:
New Drywall — Opt for drywall primer because drywall is porous and must be sealed with a sealer or self-priming paint.
Bare Wood — Use a wood primer, as wood contains tannin acids that can bleed through.
Stains — Choose a stain-blocking primer for stains, because it prevents stains from appearing through the topcoat.
Bare Metal — Use a metal primer, especially for ferrous metals, as they need to prevent against rust.
Which Primers Should You Use?
For just about every surface, there is a perfect primer. And, without a doubt, you get a better, more professional-looking paint job when you prime. But how do you choose? While some recommendations are suited for repaint and/or maintenance projects, more careful considerations must be given to primer selection when dealing with paint specifications on new construction projects. Here are some examples regarding how to choose the right primer for your surface:
Interior Stains and Odors — Some stains bleed through most primer and paints no matter how many coats are applied. The same goes for permeating odors like smoke from fires or cigarettes. The best solution is a stain-blocking primer such as BLOCK-IT® Premium.
New Drywall — Mud used on drywall seams absorbs paint differently than the rest of the drywall, which can result in blotchy, dull areas under the paint and an inconsistent sheen. In this situation, the superior option is to use a drywall primer-sealer such as VINYLASTIC® Premium.
New Wood — If your wood isn't seriously stained, a high-quality latex primer or an oil-based primer will fit your needs. If you have wood that is stained or you are painting redwood or cedar, use a stain-blocking primer such as EZ-PRIME®Premium.
Masonry — Use an epoxy-fortified primer, such as EFF-STOP® Premium, to promote excellent adhesion and resistance to efflorescence on porous masonry, including stucco, brick or concrete block.
Concrete Block — Fill a fresh surface with block filler before painting to ensure a smoother finish. If repainting, scrape off any loose or peeling paint and cover with latex paint. Use block filler such as Smooth BLOCFIL™ Premium only if the paint has been completely scraped off.
Metal — If your surface is rusty, remove the rust and apply a corrosion-resistant primer, such as BLOC-RUST® Premium for ferrous metals or GALV-ALUM™ Premium for galvanized metal and aluminum surfaces.
If you have any questions about what primer to use, please contact your local Dunn-Edwards representative.