Are there general rules of thumb for when, and where, paint primer should be used before applying the regular paint ? Interested in both interior and exterior.
Would the answers be different for oil vs latex paints ?
Guess I should also ask if there are times when it should not be utilized ?
You need only think why primer is used -- in order to make the colour coat cover better and adhere better than it would if you used no primer. So the rule of thumb is that you should always use a primer unless you know there is no need: always prime unpainted wood, prime when you plan to cover a latex with an oil paint and vice versa.
I also like to tint primers to get a better color. If you are using the latex white primers (Kilz comes to mind), the paint store will tint it for you. This helps a lot.
Also, with paint colors like red enamel, a prime of white makes the color brighter, as some colors are somewhat "transparent," and do not cover well.
Also, primers do wonders to level out the minor imperfections in a surface, as well as giving better adhesion for the final coats.
Just about any new, unpainted surface, interior or exterior, should be primed before applying a finish coat. Previously painted surfaces should also be primed if the existing finish is deteriorated, after preparing the surface - scraping, sanding, and washing. Prime can also be used as an 'undercoat' when painting over a darker color or tinted to match the new paint color and used as a first coat in situations when you know you will need two coats to cover. (I painted over a dark red with one coat of primer and a single coat of the new light blue color).
As for when a primer is not needed - if the surface is in good shape, and the new finish is close to the old, you can probably get away without priming.
Remember - primers generally do not cover like the finish coat, so don't paint yourself crazy trying to get good coverage with the primer. Just ensure that it is applied evenly, without roller or brush marks - these are hard to hide no matter how may finish coats you apply
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.