Varnish is a thick sealer with a slow dry time, so applying it is hard. It’s common to run into problems before, during, and after applying varnish.
The common varnish mistakes, why the occur, and how to fix them, are listed below.
1. How To Fix Varnish Finish Bubbles?
To fix varnish finish bubbles, do the following things.
- Pop the bubbles if possible.
- Sand the finish with fine-grit sandpaper (220-grit).
- If the bubbles don’t disappear, sand with medium-grit sandpaper (100-grit).
- Touch up the finish with one (1) varnish coat.
Varnish finish will develop bubbles if air pockets trap between coats while applying the sealer, if moisture (or water) gets underneath the varnish finish, or if you seal a damp (wet) surface.
Air pockets will get trapped between varnish coats if you shake (or stir) the sealer too much before applying it or while thinning it. The trapped air pockets between varnish coats will create bubbles in the finish.
If water gets underneath the varnish coat or if you seal a wet (damp) surface, the water will create bubbles. Ensure the moisture levels are lower than 12% before sealing a surface.
If the bubbles are popped, the air will rush out, creating tiny gaps (holes) in the finish. So, after popping the bubbles, sand the finish and touch up with one (1) coat.
Note: Varnish bubbles can be fixed by applying another coat on the bubbled finish, but this is only a temporary fix. If you do this, the new coat will eventually develop bubbles too.
2. How To Fix Yellowing Varnish?
To fix yellowing varnish, do the following things.
- Remove the varnish finish.
- Fix the surface issues.
- Apply water-based varnish as it tends to yellow less.
Varnish develops a yellow (or amber-like) color shade due to the oily deposits on the varnish formula. Since oil-based varnish uses natural or synthetic oil as its solvent, the oily deposits will create a yellowish color shade once the sealer starts to dry.
A finish will develop a yellow color shade if the surface is dirty or stained before sealing it. Ensure to properly clean the surface before painting or sealing it.
You can reduce the varnish yellow color shade by sanding the finish with fine-grit sandpaper (220-grit) and applying one (1) more varnish coat. However, the new varnish coat will develop a yellow color shade eventually too.
Use water-based varnish as it tends to yellow less since it doesn’t have oils on its formula.
3. How To Fix Varnish Turning White?
To fix varnish turning white, do the following things.
- If the white appearance is caused by moisture, sprinkle baking soda over the finish and wait 24 hours.
- The baking soda will soak the moisture and remove the whitish appearance.
The varnish finish will develop a whitish color shade if the finish is exposed to constant water, if water (moisture) is trapped between or under the coating, or if you use bleach or the wrong cleaning product to clean it.
The varnish color shade will gradually fade until it gets white or milky if you use bleach or the wrong cleaning product.
4. How To Fix Varnish Cracking?
To fix small or light varnish finish cracks, do the following things.
- Sand the finish with fine-grit sandpaper (220-grit).
- Buff the finish with polish or wax.
- Touch up the finish with one (1) varnish coat, if needed.
If the varnish finish cracks are too deep or large, remove the entire finish, sand the surface, and re-apply the sealer.
A varnish finish cracks if you over-thin the sealer before applying it, if you apply light varnish coats, or if the coating dries too fast.
If you over-thin varnish or apply light coats, the sealer coating isn’t as durable (or strong) and will crack from minimal contact. The recommended varnish thinning ratio is 3:1 (3 parts varnish to 1 part thinner).
If the varnish coating dries too fast, the particles won’t have enough time to harden, bond, or compact naturally. Since the particles aren’t bonded naturally, the coating will crack easily. A coating can dry too fast if exposed to increased heat.
The longer it takes the sealer to dry, the more time the particles have to harden, producing a more durable finish.
5. How To Fix Varnish Wrinkles?
To fix varnish wrinkles, do the following things.
- Find the cause and fix it.
- If the varnish wrinkles are caused because you re-coated too soon or because of a cold temperature, use a hair dryer to help the coatings dry properly.
- If the wrinkles are caused by a water leak, remove the entire varnish finish, fix the surface issues, and re-apply the sealer.
Varnish wrinkles are developed for the following reasons.
- You Re-coat Too Soon. Varnish wrinkles are caused if you re-coat the sealer too soon or if you apply thick coats. If you re-coat before the old coating is dry, the wet undercoat will move and shift since it’s not solid yet and create a web of wrinkles on the finish.
- Water Leak. A water leak underneath the varnish finish will wet (damp) the bottom part of the finish and cause it to absorb water and develop wrinkles.
- Cold Temperature – If you apply varnish during cold temperatures, the coating can shrink and develop wrinkles.
6. How To Fix Peeling Varnish?
To fix peeling varnish, do the following things.
- Remove the peeling varnish finish.
- Sand the surface with medium-grit sandpaper (100-grit).
- Remove dust.
- Apply a stain-blocking primer.
- Re-apply paint if needed.
- Re-apply varnish.
The varnish finish will peel off if it’s too old (10 or 20 years old), if you didn’t apply it correctly, or if you applied it over a dirty or wet surface.
If you don’t apply varnish correctly or if you apply it over a dirty or wet surface, the varnish won’t adhere properly as the dirt and moisture will prevent proper adhesion, causing the finish to peel off.