Applying Lacquer in Hot Weather

How to Avoid Flash Drying, Cracking and Dry Lines

The summer times are beautiful and well needed after a nasty cold wet winter. Its great for relaxing and having fun in but not when your working in these conditions. When the mercury rises, so do the risks of lacquer failure. Weve recently see a spout of 30 + degree weather days with us only just starting the summer this could get a lot worse. Summer jobs can turn into callbacks if finishes flash-dry or crack. Prevention is better than cure. Let’s explore some real-world issues—and the fixes that work.

🔥 The Problem: Hot surface temperature and air temperature

Warm weather accelerates drying times, but not always in a good way. Instead of curing evenly, finishes can flash-dry on the surface, forcing the finish to create a skin/layer without it doing its chemical bonding and what it needs to do to the floor. This leads to:

• Weakened protection due to incomplete chemical bonding.
• Cracking The layer hardens and shrinks before it can bond.
• Dry lines from rollers / brushes- reducing the wet edge due to heat.
• Uneven finishes the carrier ha evaporated too quick before it can level

These issues are most common when applying waterborne lacquers or primers in temperatures above 25°C ( But are more common in the even hotter days)

✅ The Fix: Control the Conditions 

To achieve a flawless finish, aim for:

• Temperature: 18–25°C
• Relative Humidity: 45–65%

Tips:

• Schedule smart: Apply finishes early in the morning when conditions are cooler. Its more time for you but I would rather come back the next morning to coat up rather than have to resechdule a resand because we tried it and hoped for the best.
• Monitor the environment: Use a hygrometer and thermometer to track site conditions. Be open and honest with the customers. If they cant appreciate it. Tell them to find someone that is willing to put there finished piece on the line.
• Adjust application: Work quickly and maintain a wet edge to prevent dry lines. Working in smaller sections at a time and preferably in a team of 2. One on the edges and one on the roller.
• Reschedule if needed: If conditions are too extreme, it's better to wait than risk a poor finish. There should be a point where you can offer the best service. Most customers will understand

🧪 Use Retarders to Extend Working Time

Retarders are additives that slow down the drying process, giving you more time to work ensuring a smoother finish. Most commonly added to waterbourne finishes and avaiible from most premium quality lacquer brands on the market. It would seem like a daft thing to do and use but just like the British weather and our British houses. There not built to deal with this type of heat. Introducing an effective way to slow down the reaction time I the primer. Lets look into some great ones on the market.

Pallmann PALL-X Retarder - Pallmann Pall-X Retarder

• Use with: PALL-X waterborne lacquers.
• Mixing ratio: Add up to 5% to the lacquer.
• Benefits: Extends drying time, improves flow, and reduces roller marks in challenging conditions.
• Mix thoroughly: Ensure the retarder is evenly distributed in the lacquer.
• Apply as usual: Follow standard application techniques, adjusting for extended open time.

Bona Retarder – Bona Retarder

• Use with: Bona waterborne primers and topcoats.
• Mixing ratio: Add up to 4% to the lacquer.
• Benefits: Enhances levelling, prolongs open time, and minimises the risk of overlaps and discolouration.
• Mix thoroughly: Ensure the retarder is evenly distributed in the lacquer.
• Apply as usual: Follow standard application techniques, adjusting for extended open time.

When the Heat’s On, Your Finish Still Needs to Hold

There’s enough pressure on-site without battling the weather too. Whether you're solo and juggling three jobs this week, or running a team that’s counting on your call — the way your finish dries matters.

By keeping your conditions right, using retarder wisely, and shifting the job timing when you need to, you’re not just avoiding callbacks — you’re backing your name with every coat you roll out.

Need help choosing the right retarder for your system?

We’ll talk you through it — no pressure, just clear advice.