Can I Get Away With Avoiding Primer When Repainting My Walls?
Repainting walls can quickly become an irritating and tedious task that will consume days, if not weeks, of your life.
Your hands will become permanently marred with paint, you will smell paint no matter where you go, and any oblong-shaped objects you encounter will remind you of another can of paint, simply waiting for you to throw it at a wall in a ritualistic sacrifice, begging the new colour to come through.
Okay, maybe it's not that bad. The work is simple, satisfying, and generally speaking, it's not the worst idea possible to try and paint your home yourself. However, if you do decide to do so, it's entirely understandable to want to try to skip any step imaginable, including applying primer before the first coast of paint.
The Hard And Fast Of It
Unfortunately, there's only really one context in which you'll be able to effectively and safely skip primer every time, and that's if you're using the same colour and coat as the previous layer of paint on the wall and the wall is in good condition.
For instance, if you would like to repaint a dark green wall that has been painted with an oil paint, then you can simply buy a few tins of the same shade of oil-based paint and begin applying it directly to the wall.
You can even brighten the shade a little without needing to worry about primer, and the new colour will begin to show clearly within a coat or two, or you can darken it entirely, which will show up fairly immediately.
In every other circumstance, though, you're probably going to need to reach for the primer. If your wall is in poor condition and needs to be patched up, whether that's as simple as some spackle or as complicated as some fresh drywall, then you're going to need to apply a layer of primer across the entire wall to make sure the surface is entirely smooth, creating a clean final coat.
If you're aiming to change the paint type, such as from oil-based paints to a new latex coat, then you'll also need a primer. Most paints don't adhere to paints of another type, and so you need to apply a specific layer of primer in-between them to make sure the overcoat goes on properly.
Should your wall be in good condition and you're simply trying to change colours, though, then you begin to have more options. If the two coats of paint are opposites, then you might want to put down a layer of primer, or you may instead for an all-in-one solution, looking for a combined can of paint & primer.
A lighter shade over darker walls doesn't require a primer but will require a good number of coats to show up properly, which means you might want to consider putting down a coat of primer anyway.