Small bubbles in DiamondFinish Clear usually form when the coating cures too quickly at the surface and traps released carbon dioxide beneath the top layer. The fix is straightforward: let the affected coating cure, sand it smooth, prepare the surface, and apply another thin covering coat under moderate, dry conditions. This guide covers what causes micro-bubbles, how to prevent them on the next coat, and how to repair a finish that already has them.
What Causes Micro-Bubbles in DiamondFinish Clear
DiamondFinish Clear is a moisture-cured urethane. During curing, released carbon dioxide must escape from the coating. If the top surface cures before the gas can escape, small bubbles can remain in the finish.
| Common cause | How to prevent it |
|---|---|
| Heavy coats or puddling | Apply thin, covering coats. Build protection with multiple coats instead of one heavy coat. |
| Recoating too soon | Wait until the prior coat is dry to the touch and does not leave a fingerprint, typically 2 to 4 hours. |
| Wet, hot, or high-humidity conditions | Apply in moderate to dry conditions. Ideal application temperatures are 50°F to 82°F. Avoid rainy conditions and high heat or humidity. |
| Overworking a brush or roller | Apply the coating to an area, then move on. Repeatedly brushing or rolling the same area can make it cure too quickly. |
| Shaking or aggressive mixing | Stir gently and thoroughly from the bottom of the can. Do not shake the can or whip air into the coating. |
| Moisture or residue on the surface | Start with a clean, completely dry surface. Do not use solvent wipes or tack cloths, because they can leave residue that creates surface-tension problems. |
How to Prevent Small Bubbles
- Prepare a clean, dry surface. Follow the applicable surface-preparation steps in the DiamondFinish Clear application directions.
- Stir gently and thoroughly. Touch the bottom of the can and lift while stirring to disperse settled material. Do not shake.
- Apply a thin covering coat. Avoid puddles, pools, and heavy passes.
- Do not overwork the coating. Brush or roll an area, then move on and allow the coating to level.
- Use the fingerprint test before recoating. The previous coat should be dry to the touch and should not leave a fingerprint. This normally takes 2 to 4 hours, depending on temperature and humidity.
- Adjust for the conditions. Avoid wet or high-humidity conditions. In high heat or humidity, additional thinning with KBS #1 Thinner or Xylene can help reduce gassing and micro-bubbling.
How to Fix Cured DiamondFinish Clear With Bubbles
- Let the coating cure before sanding. If the sandpaper gums up, allow more cure time.
- Sand the affected area smooth. Remove the visible defects, then finish-scuff the cured coating with 600 to 1200 grit sandpaper.
- Clean and dry the surface. Follow the cured-coating preparation instructions, rinse thoroughly, and allow the surface to dry completely. Do not use a solvent wipe or tack cloth.
- Apply another thin covering coat. Use moderate, dry application conditions and the thinning guidance above when needed.
If bubbles extend through several coats or the coating remains soft, remove enough material to reach a stable surface before preparing and recoating it.
Frequently Asked Questions About DiamondFinish Clear Bubbles
What causes small bubbles in DiamondFinish Clear?
Small bubbles can form when the surface of DiamondFinish Clear cures too quickly and traps released carbon dioxide beneath the top layer. Heavy coats, recoating too soon, wet or high-humidity conditions, overworking the coating, and shaking the can can contribute to the problem.
How do I prevent bubbles when applying DiamondFinish Clear?
Stir gently and thoroughly without shaking, apply thin covering coats, avoid puddling, and work in moderate to dry conditions. Apply the next coat only when the previous coat is dry to the touch and does not leave a fingerprint.
How long should I wait between coats of DiamondFinish Clear?
DiamondFinish Clear is typically ready to recoat in 2 to 4 hours, depending on temperature and humidity. Use the fingerprint test instead of relying only on the clock: the coating should be dry to the touch and should not leave a fingerprint.
Can I thin DiamondFinish Clear to help prevent micro-bubbles?
Yes. Use only KBS #1 Thinner or Xylene. About 10% is suitable when brushing for improved flow, 10% to 20% may be used when rolling, and 10% to 15% is normally adequate when spraying. DiamondFinish Clear may be thinned up to 30% when conditions require it.
How do I fix cured DiamondFinish Clear that has small bubbles?
Let the coating cure until it can be sanded without gumming the sandpaper. Sand the affected area smooth, finish-scuff the cured coating with 600 to 1200 grit sandpaper, clean and dry the surface according to the application directions, then apply another thin covering coat.
Conclusion
Micro-bubbles in DiamondFinish Clear come down to the surface curing faster than trapped gas can escape. Thin covering coats, gentle stirring, the fingerprint test between coats, and moderate, dry conditions prevent them, and a bubbled finish is almost always recoverable by sanding smooth and applying one more thin coat. When in doubt, review the full application directions before you recoat.
