To the uninitiated, primer seems like a rip off. An expensive product you put on before you paint that you never see. But primer can be essential. So here’s a primer about paint versus primer, as well as when you need it, when you can get by without it, and what paint plus primer in one means.
Paint and primer: the difference
Primer looks for all the world like another kind of paint. But its formulation is different. It tends to be a bit thinner than paint, and it contains more resins than paint does. Paint’s job is to cover and recolor. Primer has a different job. Its job is to seal and promote adhesion. That’s the major difference between paint vs primer.
Just like there are specialty paints for different applications, there are specialty primers as well. Self-etching primer for metal won’t do a great job if you use it on your house, and primer intended for painting your house won’t do so great on metal. So when it comes to paint vs primer, this is one place they have a similarity.
When to use primer
When you paint a surface that has never been painted before, you need to use primer. Otherwise, the new paint will not adhere well. You will find it takes more paint to cover the surface, it tends to run, and over time, the paint will flake off.
If you use primer, you may very well find it takes two coats to cover, but the paint job will last for years, or even decades.
It’s also a good idea to use primer when making a major color change. Red and yellow are notoriously difficult to cover, and bright colors in kids rooms can also be very difficult to cover. Using primer makes the job a bit easier.
Something else you can do when painting your house is get the primer tinted. Some paint stores don’t like to tint primer, because it can be extremely difficult or even impossible to get a perfect color match. It’s okay. The match doesn’t have to be perfect. A tinted primer that’s close will be more forgiving than trying to cover white primer with a topcoat other than white.
If you are painting a similar color, and the underlying paint is in good condition, you don’t need primer necessarily. Two coats of paint will probably do the job, so a coat of primer isn’t really saving you anything.
If the underlying paint is not in great condition, there is a special primer you can use. There are special primers for peeling paint. Big box home improvement stores sell a variety made by Zinsser called Peel Stop. Independent paint stores sell a brand called Mad Dog Primer. These primers have a rubbery additive in them that seeps under peeling paint and sticks it back down. It also provides a stretchy base that helps the top coat resist cracking. These specialty primers for peeling paint are more expensive, but they save you a lot of time. They reduce how much you have to scrape and sand, and they make your topcoat last longer.
When it comes to spray paint primer, you can get general purpose spray primer, and you can also get specialty primers that bond to plastic, etch metals, or treat Rusty metal. Spray primer typically comes in four or five different colors: oxide red, Green, gray, black, or white. When in doubt, gray is probably the one you want, but if your top coat has a lot of red or green in it, using red or green primer makes the job easier. And of course if you are painting something black, black primer makes the job easier.
What about paint plus primer in one?
In recent years, a number of products that claim to be paint and primer in one have come on the market. You see them in spray cans, but also in house paint.
These products aren’t exactly new. What they really are is a higher grade of paint with more solids in them than cheaper paints.
And when you use them under the conditions they are designed for, they really work.
As long as the paint you are covering is in good condition and is clean, these more expensive all in ones can cover in two coats. And if the color is close, you can often get the job done in a single coat.
But make sure you read the instructions on the product. For example, there is no getting around putting a primer coat on new, unpainted drywall.
But under the right conditions, these all in one products can save you a lot of time by saving you a step or two. When I need to get a room painted in a hurry and I’m not making a major color change, these all-in-one paints can be a lifesaver.