How Much Scraping and Sanding is Really Necessary? (2024)

FAQs

How Much Scraping and Sanding is Really Necessary? ›

So here's a primer on scraping and sanding – and not always needing primer. How much scraping is enough? As a rule of thumb, you can stop scraping when the surface is no longer flaking. Remember, the paint must bond to the surface, and if that surface is loose and flaky, then the new paint has nothing to cling to.

Do I need to sand after scraping? If you've done a good job of scraping away loose chips, most people will not be able to detect the edges of pre-existing paint on the surfaces. Certainly, various wood has unique qualities, but overall, you should not need to sand your exterior prior to painting.

In short, scraping is an aesthetically pleasing activity, while sanding with a machine is a noisy, messy chore. Can you get smoothness with a scraper that is indistinguishable (after the finish is applied) from that of 220 sandpaper? The short answer is yes.

Not removing the previous paint from the wall's surface could create bumpy and uneven finishes that will only continue to build as you add more layers. When adding layers to a poor paint job, you accentuate those defects, making them more noticeable. Starting with a clean slate gives you a smooth and even foundation.

If the existing paint is of the same type and the wall is in good condition, you can go ahead and paint without sanding. However, when it comes to wood, you may have to sand for proper adhesion. However, you can also skip the sanding process and make do with a primer.

The golden rule of sanding is to start with a grit coarse enough to quickly remove surface imperfections and follow with incrementally finer grits.

Surface skin cells migrate from one side of the wound to the other, covering the wound with cells to form the new skin. Depending on the injury, the site is left with a scar. Generally, scar tissue isn't as strong as undamaged skin.

Research indicates real benefits from 'scraping therapy,' like reducing chronic pain, headaches and stress.

Choose a fine-grit sandpaper.

If you are scuffing bare wood, or another surface, in preparation for priming, painting, and/or staining, you will need something between P120 and P150. If you are scuffing between coats of paint or sealer, choose something between P180 and P220.

As mentioned earlier, the amount of stock an abrasive can remove is dependent on grit size. A three-head sander can enable you to run a grit sequence of around 100-150-180 and eliminate around 1/32” of material in one pass.

How much old paint do I need to scrape off? ›

As a rule of thumb, you can stop scraping when the surface is no longer flaking. Remember, the paint must bond to the surface, and if that surface is loose and flaky, then the new paint has nothing to cling to. Be sure the surface is clear of loose paint chips and debris to get the best adhesion.

If the current wall is smooth, clean and covered with the same type of paint (both are oil-based for example), you can head straight for the paint. You need to fill holes, spackle and sand*, maybe even cut a new piece of drywall in to the existing wall.

Paint will peel if walls weren't properly prepped before painting or if the walls were subject to a leak, high humidity, high temperatures, or too much sunlight. Paint can also peel if too many layers of paint are added to a wall.

Even if you can get away with one coat, two coats are better if you can afford it. Two coats of exterior paint will retain the color and sheen far better and longer, protecting your home more thoroughly and extending the time before the next repainting.

Latex-based paint can go bad, but it takes a while. You'll probably be able to keep it for up to ten years, with a few caveats. The biggest factor influencing latex paint's shelf life is if the can has ever been opened. If the paint is unused, you'll get more life from it.

1. Satin/eggshell: Best for siding because it's a low-reflective finish that's good at hiding surface imperfections. It has a slight gloss, so it stays cleaner, is more easily washed, and stands up to abrasion better than flat or matte paints.

Sanding may still be required:Paint strippers work well, but there are cases where you may end up spending a significant amount of time sanding after stripping to finish cleaning the wood surface.

For most projects, you only need to sand and scrape off loose, cracking, chipping, or peeling paint. However, all paint needs to be sanded off of wood that will be stained.

In most cases, you will scuff sand a bare surface before applying anything, and sand again between coats of paint or sealer. Here is what you should look for: If you are scuffing bare wood, or another surface, in preparation for priming, painting, and/or staining, you will need something between P120 and P150.

It's almost always better to strip than to sand. To begin with, except in cases where the old finish is flaking off, it's a lot more work to sand than to strip using a paint-and-varnish remover.