Paint primer covers imperfections and provides a smooth base for paint to stick to. But, because of its thick flow, you can encounter problems while applying primer, especially on rough surfaces.
We will look at some common mistakes, why they occur, and how to fix them.
1. Paint Primer is Cracking
A primer coating will crack if you apply thin coats. This is because thin coats won’t cover the surface properly, and the coating will have poor durability that will crack from minimal usage. This usually happens if you over-thin it.
A primer coating will also crack if the coating dries too fast. If you expose the coating to increased heat, its solvent will evaporate faster than it should, and the particles won’t have enough time to harden or become compact. This leads to a poor bond between paint particles, and this can cause the coating to crack.
To fix a cracking primer coating, remove the entire coating and re-apply it. Here’s how to do it:
- Use a trowel or scraper to remove the cracked primer coating from the surface.
- Sand the surface to remove filth and primer residue.
- Repair gouges and imperfections on the surface.
- Sand again with fine-grit sandpaper to smoothen the surface.
- Re-apply two coats of paint primer and leave to dry.
2. Paint Primer is Forming Bubbles
The finish will develop bubbles if air pockets trap inside the primer coating before you apply it. These bubbles can pop after a while and scar the finish.
Bubbles can also appear if you apply primer over a fresh porous surface. Fresh porous surfaces have lots of pores that are filled with air. So, once you apply the primer, the air trapped will cause bubbles in the finish.
Also, if you stir paint primer too hard or fast, you will trap small air pockets in the coating. So, once you apply primer, these air pockets will form bubbles.
The best way to fix bubbles in a paint primer coating is to pop them, sand the surface, and touch up the surface with another coat. If that doesn’t work, you must remove the entire coating, sand the surface, and re-apply it.
Here is a guide for this:
- Pop the bubbles in the coating.
- Remove primer from the surface.
- Sand the surface with fine-grit sandpaper.
- Apply a coat of sanding sealer on the surface.
- Re-apply two coats of the paint primer and leave it to dry.
Sanding sealer will cover the pores in a porous wood and prevent air from creating bubbles.
3. Clumps in Paint Primer
Clumps are solid particles that appear if you expose paint primer to air. If the primer isn’t sealed properly while storing, air can get into the container and cause the particles to clog or clump up.
Clumps will also appear if the coating is exposed to temperatures below 40 degrees (F). The low temperature will cause the primer coating to solidify.
The best way to fix clumps in a paint primer is to thin it. The thinning compound will dissolve the clumps and loosen the primer.
Here is a guide for this:
- Pour the primer paint into a clean paint bucket.
- To thin water-based primer, use water and to thin oil-based primer, use mineral spirits.
- Stir the mixture for a few minutes.
- Test the coating before applying it.
4. Sticky Primer
A primer coating will get sticky if you re-coat it too soon. If you re-coat while the coating is still wet, you will trap the solvent between coats; this causes the coating to turn sticky. Also, the coating will turn sticky if you apply primer over a wet surface.
To fix a sticky primer, increase the heat around the coating, so the solvent evaporates faster. You can use a hairdryer or heat for this. If this doesn’t work, you must remove the coating, fix or dry the surface, and re-apply it.
Final Words
In summary, it’s common to run into problems while applying primer paint due to the nature of the coating. However, you can always fix it by removing the coating and re-apply it.
Tony Adams
Tony is a professional painter and an author of DIY Geeks. Tony has completed over 1,000 painting projects for his clients. It's safe to say he knows what he Is talking about,