Primers 101
When it comes to exterior painting, if you know a lot about it, or even if you don’t, when and where to use primer before painting can be confusing. At the paint stores, a lot of times you’ll get upsold on a primer, because you’re told that you 100% need one. In most cases, this actually isn’t true!
A typical scenario involving an exterior repaint will be that the body, trim, fascia, etc, have all been previously painted. Even on new construction, the most common types of siding will come out pre-primed. The most important thing to know is that if the siding has been painted previously and is in good condition with no peeling, blistering, or exposed bare wood, then there is no need to prime it.
On most houses, we’re not priming anything unless there’s some type of damage, usually caused by weather, sunlight, or water. If there are any areas of the siding that are damaged, or areas where scraping and sanding is needed, then you’ll definitely want to prime those to protect the surface and elongate the life of the siding.
Depending on the climate, homeowners should be aware of the fact that they need to paint their homes every 9-12 years to ensure proper protection of the siding. A new coat of paint can do a lot to prevent damage.
You’ll also want to be priming over any surfaces that were previously painted with an oil-based paint. That’s pretty rare to encounter these days, especially on exteriors, but it is pretty common with interior rooms. Any surface that is shiny or glossy can indicate an oil-based paint. Sanding and priming will give the new top coat something to bite onto, rather than just falling off and creating fisheyes.
Regarding some specific scenarios you might run into, I usually like to prime gutters if they haven’t previously been painted and are the original powder-coated metal. This is due to some of my previous experiences, where I’ve had paint crinkle on gutters for unknown reasons. Once we started using a bonding primer, this issue began to disappear. Additionally, stucco is not a surface that you should worry about priming.
But if you’re running into scenarios where you do have damage to the siding and are needing primer, which one should you pick up? The best of the best these days comes from Zinsser - I’ve used a lot of their primers for years and years, and they are tried and true amazing.
One of the most versatile, useful, and best primers on the market is the Peel Stop Triple Thick primer. This is a high-resin primer that fills, seals, and glues, making it easy to solve blistering and siding failure. Peel Stop stops peeling paint and creates a smooth unique finish that seals weathered surfaces.
If you’re needing to do a lot of priming with this product on an exterior job, make sure you include that in the bidding process and price, as this can be a time-consuming process. The best method for application is brushing it on for the best adhesion and penetration - you want to make sure you’re getting it in every damaged spot and area, really pushing it into the wood fibers and getting under the laps of siding. Make sure to brush with the grain instead of against it! I’ll usually be using a Chinex filament brush, a 3” angled-sash like the Premier Riverdale.
I’ve been using this product for a long time, and with most homes in Idaho, I’m going to be using at least a half-gallon of the product. On the last exterior I did, where there was a lot of damaged siding, we used about four gallons on the entirety of the project. Check out this video to see Peel Stop Triple Thick in action!
After applying Peel Stop and letting it dry, depending on the scenario, you’ll most likely want to hit the area with some sandpaper or a sander to knock down any exposed fibers. Sand those down for a smoother finish. I’ll either use an Ekadiamond sponge, or hit the areas with my 3x4 sander.
Another feature I like about this product is the white colorant in it. A lot of primers I’ve used similar to this in the past dried clear, making it hard to see where you’ve primed. I like for the customer to be able to easily look and see that we’ve been priming and making progress, and when a product dries clear that’s a lot harder to do. You want everyone to know that you’re priming what you need to prime, plus it just helps you out as well too when you’re doing the work.
This is an interior and exterior water-based product that can do everything it feels like! It works super well to seal the edges of peeling paint and hangs super well on a brush, with no drips or runs. It dries fast and you can recoat or top coat within two hours with any latex or alkyd paint. Make sure that you don’t just top coat over damaged siding, because the issues will just come through, and paint won’t seal and fix issues like Peel Stop can.
This product is an excellent stain-blocking primer that seals stains, graffiti, grease, and oil. It’s a classic and universal interior and exterior water-based primer that even has a low odor profile! One of the recent times I’ve used this product has been on an exterior to deal with soot damage. There was an interior gas-burning fireplace with an external vent, leading to an exterior wall with soot damage and creating a large swath of soot up to the fascia.
In scenarios like this, you wouldn’t want to just paint over the soot, because it will likely absorb and bleed through, leading to a discoloration of the paint. So, after cleaning it off as much as possible during the pressure washing phase of prep, you’ll want to prime over the area and seal the soot in. This product comes in quarts, gallons, and spray cans, but a lot of times, it’s best to brush the product in to ensure proper adhesion.
Bullseye 1-2-3 dries in thirty minutes, and you can top coat in an hour. It sticks to all surfaces, including glossy surfaces. Plus, it inhibits rust when applied to metal surfaces, and it provides a mold & mildew resistant film. Zinsser makes a lot of really cool primers, and this one is another one of my favorites. It’s a flexible acrylic formula, and you can apply it in temps as low as 35 degrees. Watch this video to seal me deal with the soot damage!
Instead of blocking stains like Bullseye 1-2-3, Cover Stain kills stains and provides an enamel undercoat - this product will permanently seal all stands to ensure a smooth top coat. The best scenarios for this product involve when there are nicotine, smoke, and water stains. It can also be used to solve bleeding from cedar and redwood.
The last project I used this on was in the repair of a stone chimney that was in disrepair. While the internal fireplace had long been removed, the external chimney on the roof was chipping and pieces were falling away, so we needed to seal this up quickly to keep water from leaking into the home below. This video shows the process of me fixing up this chimney.
In my experience, Cover Stain works well to seal porous surfaces and stone, so I began applying it to the problem areas on this chimney to start sealing before I hit the cracks with some AU-1 construction grade sealant.
Another primer you should definitely know about is Zinsser’s Mold Killing Primer - the use for it is right in the name, this product kills mold, mildew, and odor-causing bacteria. A lot of times, issues like mold and mildew will be spotted during the pressure washing process, and you should be trying your best to remove as much of it as possible with the pressure washer, before moving onto using a mold killing primer.
With Zinsser’s primer, you can apply it right over the mold. This is a water-based fungicidal protective coating that helps to bind chalky siding and deal with spot mold on vinyl siding. One of the most common areas that people use this in a lot is in bathrooms, and also basements, locker rooms, offices, factories, etc. Use interior or exterior! On the last exterior I worked on, the back of the house featured a lot of mature landscaping that created a lot of moisture and shade and allowed a lot of water to come down on the fascia, leading to mold growth.
I was able to brush this primer right over the mold and paint over it within an hour. This is also able to be used on metal surfaces, and I was able to apply it to a metal awning where there was some spot mold growing. In this video, you’ll see the before and after of fixing up some mold on fascia. And if you’re in need of some, check out our online store and pick up a gallon or spray can today!
Whenever I’m painting cabinets or furniture, B-I-N primer is always on hand. This is another great primer to seal, block out stains, and reduce odors, but I’m usually going to be using it in cases where I’m dealing with contamination issues.
Fisheye is a result of a contaminant, usually on a wood-painted surface. The paint will begin to fall away in a circular pattern, which has led to everyone referring to it as fisheye. The reason for this is a surface tension difference between whatever the surface was painted with originally, and what it is being coated with now. Usually, this might be an incompatibility between oil-based and water-based paints. The paint will just float on top of the surface, and can dry just like that, instead of biting down into the surface.
B-I-N is a shellac-based interior & spot exterior primer that sticks to all surfaces. I usually keep a spray can of it on hand to spot prime, but if you’ve got a large surface to contend with, or a big project, you can run a gallon of it through an airless sprayer. Before applying B-I-N, make sure you sand away any fisheye or residue that you might have encountered, otherwise you will still be able to see it after you prime and top coat.
While I usually use this on cabinets and furniture, this is my favorite primer to use in cases of blocking pet or smoke odors, like that from fire damage. No matter the job, I recommend keeping some B-I-N primer around, especially if you’re frequently working with cabinets and furniture. As you can see, no matter the Zinsser primer, you’ll be able to use it for a variety of scenarios.