Do We Need To Sand Before Painting?

We know what you’re thinking: painting is laborious enough as it is – so do we really need to sand the walls down beforehand?

Well, the answer is, not always, but you should definitely do a thorough check of the area you’ll be painting and look out for any rough spots.

Do we need to sand before painting

Rough spots will need sanding whether they’ve been previously painted or not, otherwise, you won’t have a smooth surface to work with, and your paint job will look, well, shoddy.

To provide a clean, smooth surface to work with, use sandpaper or a sanding block to even out the surface and wipe away dust and debris with a damp cloth before leaving the area to dry thoroughly.

Do I need to sand before repainting?

Treat cracking or flaking paint on previously painted surfaces as a red flag.

This can be caused by several things, but the most common reason for flaking or cracking paint is poor preparation of a surface prior to painting.

It’s not a good idea to attempt to conceal cracked paint with a new coat, either. You should instead remove any flakes by sanding or scraping the wall before repainting.

The type of paint that was previously applied will also dictate the sandpaper you use.

  • You will need to sand walls before repainting if they’ve been previously painted with a gloss or high-gloss paint.
  • For walls that were previously painted with water-based paint, use fine-grit sandpaper to gently buff the surface, and
  • For oil-based paint, a medium-grit sandpaper (100- to 150-grit) will do the job.

As usual, be sure to wipe away any debris and leave the wall to dry completely before you start painting.

What happens if you don’t sand before painting?

You’ll simply end up with a less impressive paint job.

When you sand down a surface, you’ll not only be left with a smoother surface to work with, but you’re creating a more adhesive area for the primer, paint, or stain to stick to, resulting in a more even finish and longer-lasting results.

In some instances, you may get away with not sanding, and you won’t be able to tell.

For example, if you’re just doing minor touch-ups, there may be no need to sand, however, it’s always best to do so if you want to ensure the smoothest results.

Things to bear in mind

Remove wallpaper

It’s not recommended to paint over wallpaper, especially if the wallpaper has a high sheen or a heavy texture.

Plus, even the highest quality paint struggles to hide wallpaper seams. You’ll want to strip all wallpaper first and then prepare the walls for sanding and priming before painting.

Clean the area first

While coarse sandpaper is effective at removing dirt and debris due to the friction, it’s important to always clean the area before sanding.

Water and detergent will provide a far more thorough job of cleaning away any dirt or dust, and ensuring you have a super clean surface to work on.

If you’re planning on painting your home’s exterior, power washing should be the first thing you do before sanding.

Then once the facade has dried, you’ll be able to sand down any rough patches and ensure the strongest adhesion for your paint.

Remove mildew

It can be tempting to just cover up imperfections, but when it comes to mildew, this isn’t a good idea, as it’ll only come back to haunt you.

Mildew will simply grow through new paint, and you’ll then be faced with a much harder cleaning job.

Be sure to wear gloves and goggles, and then tackle mildew stains with a sponge and a solution that is three to four parts water to one part bleach.

Apply the solution, allow it to act for a few minutes, then scrub the affected area with a soft brush, before rinsing with clean water and allowing it to dry.

Grit rating

The grit rating of sandpaper ranges from 40 to 400 and this refers to the sandpaper’s coarseness and particle size.

Higher-grit sandpaper is finer and characterized by smaller particles, while lower-grit sandpaper has larger particles and is generally rougher.

The grit size you use to sand down the surface will depend on what you’re trying to achieve, and at what step of the sanding process you’re in: coarser, lower-grit sandpaper will usually be used for initial sanding purposes as it is effective at getting rid of more material quickly, whereas finer sandpaper is typically reserved for the end of the sanding process, to finish off the job and provide a smooth finish ready for painting.

Prime, prime, prime

Never underestimate the power of a good primer. Primer helps you get the most out of your paint, and will also help conceal stains and provide a barrier on porous surfaces.

It creates an optimal surface for your paint to adhere to, providing a smooth, uniform finish.

Leave a Comment

Your email address will not be published. Required fields are marked *