Not all types of paint primer are created equally. The reasons to use one type over the other will depend on the type of surface you are painting, the elements the paint will face, and how much you want to seal the wood (or other material).
Choosing the right primer is easy once you know each type's differences and strengths.
There are three types of primer paint: oil, latex, and shellac. This blog post will discuss the reasons to use primer in the first place and when to use each type of primer.
Why Should I Even Use A Primer?
To understand why one would use a specific primer vs. another, it’s important to understand why we’d use primer in the first place.
Primer is used for three main reasons:
To Cover
If you are painting a surface that already has color, your new color might not be enough by itself to cover the old color. The previous color, especially dark, can bleed through and disrupt the new finish. Adding a primer layer gives you a good base to apply the new paint. Specific types of paint can’t adhere to other types, like oil paint over latex. In this case, primer can act as an intermediary.
To Seal
Most materials are porous, and some more than others. Some woods will soak up the paint, and you might find yourself applying layer after layer until you finally have the finish you want. The primer creates that base layer for you and seals the surface, so you only need one or two layers of paint. Primer contains different binders that can seal porous surfaces like wood and drywall.
For The Finish
A coat of primer helps to even out the surface so that when you do add your paint, the finished product will be smoother and more even. Your paint will better stick to the primer than the original surface, leaving you with a final layer that is less likely to crack or chip. Fewer stains and blotches will show through.
The Three Types Of Primer
Oil-Based Primer
Best For: Outdoors, raw wood and drywall, painted or stained surfaces, rough surfaces.
Oil is about versatility and can double up for many jobs that acrylic primer would be used for. Oil-based primer will adhere to almost any surface and is a master at covering up previous paint or dark stains—once the primer is on, the surface below will not show through.
If you cover an outdoor wall, you want to choose oil primer. It deals well with extreme hot and cold; if the primer stays in place throughout the year, so will the top coat. And its durability extends beyond that too. If you are painting high-traffic areas—where there is going to be a lot of dirt, touching, or scuffing—then use an oil-based primer.
If you use an oil-based primer, you must plan for it. The other two primers dry quickly, but the oil does not and needs some time to evaporate and leave the pigment. It is best to leave it for 24 hours before painting. You also need to be careful about how you dispose of it. If you have some leftovers, take them to where they can be safely discarded.
Our tip is to let it dry out and then put the dry paint in the garbage.
Acrylic (Latex) Primer
Best For: Porous materials like soft wood, concrete, and brick.
The main difference between latex and oil-based primer is the carrier. As you might have guessed, oil primer used oil, while acrylic used water. This makes acrylic primer easier to deal with during and after painting. It is also easier to clean up if you spill any. Acrylic primer is quick-drying, taking only a few hours compared to 24 hours for oil.
Acrylic primer can be applied to many surfaces and will hold up better than oil primer on some of those surfaces, especially the more porous ones. You will mainly use this indoors, which is great for places where satins might appear.
But, you will not use this primer if you need to cover a previous paint job or tough stains. It is easy and versatile to use, but it does not do well at covering, so be sure you are applying it to raw surfaces or lighter colors.
While it does not contain the same harmful chemicals that oil-based primers have, it is still best to have ventilation when you are working indoors.
Shellac Primer
Best For: Interiors, wood, plastic, plaster, and metal.
Shellac has been around for a long time, and that is because of its sealing properties. If you have a surface that you need to seal before painting or want to cover up a stained surface, then shellac is what you need.
Shellac dries even quicker than acrylic, drying within an hour in most cases, and this is perfect if you are doing a point job in one day. By the time you have finished your second or third wall, the first wall will be ready for more paint.
It is an extremely adhesive paint, so it will adhere to surfaces without soaking in, giving you a good base to start with. It also compares favorably with oil-based primer in terms of cleaning. The paint is durable and can be wiped and cleaned easily.
The only real downside is the chemicals used in the paint, and while it does not have as many as oil primer, you should use ventilation whenever you paint with shellac.
Which Primer Should I Use?
From the above information, you should now know which primer best suits your job, but use this simple guide if you are still unsure:
If the surface will take acrylic paint, use acrylic paint. There are fewer fumes and chemicals, and you will be able to deal with the paint easily both during and after the painting.
Acrylic is also best for unfinished drywall.
Choose an oil-based primer if you need to paint raw wood, stained wood, or a previously finished surface.
Choose shellac if you need to create a strong foundation or have damage to cover up.