Looking to achieve professional paint finishes every time?
Painting surfaces without any prep is by far the most common mistake made in any painting project. People pick up a brush or spray gun and start painting with little consideration for what’s underneath. Then wonder why the paint doesn’t last.
Here’s the secret…
Paint Prep is:
- Free (or very low cost) to do
- Simple to do correctly
- The difference between professional paint jobs and DIY fails
If you skip prep. You’re flushing every dollar you spent on paint away.
In this post you’ll learn:
- Why Surface Preparation Is So Important
- Selecting The Correct Abrasive Materials
- Step-By-Step Process for Prepping Any Surface
- Surface Prep Mistakes You’ll Want to Avoid
Why Surface Preparation Is So Important
Surface preparation is by far the most important step of any painting project. If done properly, paint has the best chance of lasting many years. Done incorrectly or not at all… your paint will start failing almost immediately.
One survey even found 40% of coating failures were due to poor surface preparation. That means 2 out of every 5 times paint peels, cracks or fails… It’s because of something that happened (or didn’t happen) before painting.
Paint needs a clean surface to bond to. Unless you sandblast or chemically strip every surface before painting… you need to sand in order to prepare it.
Consider this scenario…
You paint a wall or piece of furniture. It looks great! But because you didn’t sand / properly prepare the surface… cracks and peeling begins to show within weeks.
The paint needs something to key into or grip. Painting produces what is called a mechanical bond with the surface. By sanding you create tiny scratches on the surface for paint to hold onto. When there are no scratches… paint lifts right off.
And it doesn’t matter if you spend $100 on paint or $10…
If you don’t prepare the surface… you’re throwing your money away.
Painting is all about surface prep. That’s why professional painters spend more time prepping BEFORE they paint than they do actually painting.
Selecting The Correct Abrasive Materials
Notice that paint hasn’t been mentioned yet. That’s because before paint should ever touch a surface… sanding materials should be used.
Now this is where a lot of people get it wrong. Both DIYers and professional painters.
To prep large flat surfaces like doors, tabletops, decks, fencing… you need a combination of aluminum oxide sanding belts and a quality belt sander. Together they will strip old coatings and smooth out imperfections faster than any other combination. Plus aluminum oxide sanding belts can be used on wood, metal, painted surfaces and more.
Here’s why that’s important…
When prepping surfaces to paint. Choosing the correct abrasive products is key. Using the wrong abrasive can damage your surface or leave it super smooth with nothing for paint to adhere to. Aluminum oxide sanding belts remove material quickly… but leave you with a smooth surface perfect for priming.
You won’t use the same grit sandpaper / sanding belt for every stage of the surface preparation process. You start with coarse to remove old paint and material quickly. Once most of the old paint is removed, you move up through the grits until you finish with fine grit sandpaper. By starting coarse and working your way up through the grits you’ll end up with a perfectly prepared surface ready for primer.
This doesn’t just apply to painting. The abrasive market reached $47.65 billion in 2024. That’s because every industry that utilizes abrasives knows one thing…
Having the right type of abrasive for your application makes all the difference.
Buy cheap sanding products and they will wear out quicker, cut unevenly, and leave you with a poor surface to paint. Invest in quality aluminum oxide sanding belts and you’ll be setting yourself up for success.
Step-By-Step Process for Prepping Any Surface
Ok, now it’s time to learn exactly how to prep surfaces before painting.
Clean The Surface
The first step to prep any surface is to clean it. Make sure there’s no dirt, dust, grease or grime on the surface. Use warm soapy water for most applications. For oily or waxy build up, use a degreaser.
Painting over dirty surfaces is the number one cause of paint failure. Even a thin layer of dust can cause adhesion problems.
Remove Old Coatings
If your project surface has existing paint thats peeling, bubbling, or cracking… strip it off! Use a coarse grit aluminum oxide sanding belt to sand down to the bare material.
On edges, corners or tight spaces a sanding block or orbital sander will work. But for large surfaces, use a belt sander and the correct abrasive sanding belt to make quick work of the job.
Sand The Surface Smooth
Once you’ve removed old coatings, start sanding with medium grit and work your way through the grits until finishing with fine sandpaper. This will produce a smooth, uniform surface for paint.
Remember…
When sanding you aren’t trying to make the surface slick smooth. By sanding you are creating small scratches for paint to adhere to. A perfectly smooth surface will cause paint to fail.
Apply Primer
Once you’ve finished sanding, wipe down the surface with a tack cloth to remove any dust. Then apply primer designed for the surface you’re painting.
A good quality primer will:
- Seal the surface prior to painting
- Create a bonding layer between the paint and surface
Never skimp on primer. Think of primer as the glue between your prepped surface and your topcoat.
Final Inspection
Wipe down your surface with your hand. You should be able to run your hand over the surface and not feel anything. If your finger catches on something… sand lightly with fine grit sandpaper and wipe down again.
Surface Prep Mistakes You’ll Want to Avoid
These are fail-proof steps that everyone should follow when prepping surfaces. However, even the most seasoned painters make these surface preparation mistakes…
- Skipping Cleaning: Paint will not adhere to dirty surfaces. Grease and dust are the number one causes of paint failure.
- Using incorrect grit: Start too fine and you won’t remove old paint. Start too coarse and you’ll sand through your surface.
- Not allowing surfaces to dry: Painting over a wet surface causes blistering and peeling.
- Painting in extreme temps: Hot or humid temperatures can cause improper curing.
- Rushing through surface prep: Though it may be tempting to cut some corners during this step. Take your time.
Bottom Line
Preparing surfaces before painting is by far the most important step in painting. No matter if you’re painting a wall or a cabinet. Taking the time to clean, prepare and prime will set you up for success.
Let’s recap real quick…
- Clean the surface you’re painting
- Remove any old paint that’s failing
- Sand in progression with quality aluminum oxide sanding belts
- Prime the surface to ensure paint adhesion
- Inspect your work!
Painting surfaces without any prep is the best way to ruin a paint job. All it takes is a few minutes of sanding and your paint will adhere like it was meant to be there.