Drying Techniques for Water-Based Wood Joinery Coatings in Industrial Settings

Drying Techniques for Water-Based Wood Joinery Coatings in Industrial Settings

Drying water-based wood joinery coatings in an industrial setting demands a delicate balance of time, temperature, and technique to achieve optimal results. From the application of coatings to their final curing, each step in the drying process plays a crucial role in ensuring the quality and durability of the finish. In this blog, we will explore key aspects of drying water-based wood joinery coatings, including drying tunnels, flash-off periods, time between spraying coats, handling times, and fully curing, providing insights into best practices for industrial operations.

Understanding Water-Based Wood Joinery Coatings: Water-based wood joinery coatings offer numerous advantages, including environmental friendliness, low VOC emissions, and ease of cleanup. These coatings provide excellent adhesion and protection while highlighting the natural beauty of wood surfaces. However, their drying process requires careful attention to a range of factors to achieve the desired finish quality.

Drying Techniques in Industrial Settings:

Flash-Off Periods:

• Flash-off periods refer to the critical interval between coating application and entering the drying tunnel.
• During this period, water evaporation occurs, allowing the coating to level and release trapped air bubbles.
• The flash-off is defined by little to no air movement and an ambient temperature. If force drying is taking place, then an initial flash-off is essential.
• The duration of the flash-off period depends on factors such as coating viscosity, ambient temperature, and humidity levels.
• Proper flash-off periods help prevent defects like orange peel and ensures a smooth, uniform finish.

Drying Tunnels or drying spaces:

• Drying tunnels are essential equipment in industrial wood coating operations, providing controlled conditions for the drying process.
• These tunnels typically feature conveyors that transport coated wood pieces through a series of heated chambers, facilitating uniform drying.
• Adjustable temperature and airflow settings allow operators to tailor drying conditions to the specific requirements of the coating and substrate.
• Although purpose-built tunnels are desirable, simply having an area with airflow and a controlled temperature is sufficient. Areas with controlled humidity and temperature mean you can follow dependable drying and curing times between coats, maintaining time efficiency and finish quality.

Time Between Spraying Coats:

• After applying the initial coat of water-based coating, allowing sufficient drying time between coats is essential.
• The recommended time between coats varies depending on factors such as coating thickness, ambient conditions, and substrate absorption. Ensuring that timber moisture is between 12%-14% for exterior joinery. Water evaporates from the paint away from the timber, but also through the timber itself. Meaning the timber will get wetter before the paint dries. If there is already too much moisture in the timber, this can result in delamination.
• Typically, a period of up to 4 hours is sufficient before applying subsequent coatings.
• Adhering to proper drying times between coats promotes adhesion, minimises the risk of sagging or runs, and enhances finish durability.

Handling Times:

• Once the final coat is applied, allow adequate drying and curing time before handling or packaging is crucial.
• Handling times vary depending on factors such as coating type, thickness, and environmental conditions.
• While water-based coatings may dry to the touch quickly, full curing and hardness may take several hours to days, depending on the formulation.
• Premature handling can lead to surface defects or marring of the finish, compromising the overall quality of the coated wood joinery.

Fully Curing:

• Achieving full curing is essential for maximizing the performance and durability of water-based wood joinery coatings.
• Full curing refers to the complete cross-linking and polymerization of the coating film, resulting in optimal hardness, chemical resistance, and adhesion.
• Depending on the specific coating formulation and ambient conditions, full curing may take anywhere from 24 hours to several days. The coating will be vulnerable in this period and may be soft to touch.
• Providing adequate curing time allows the coating to reach its maximum performance properties, ensuring long-lasting protection and aesthetics.

To help with the drying process we believe that certain equipment is essential for any joinery workshop. Although in the dry ambient months this equipment may not seem necessary, there will come a time when the shop is a little too hot, cold, wet, or dry to be spraying hassle-free. With a small investment, consistent spray quality can easily be assured.

Timber Moisture Gauges:

• Pin-type moisture meters or non-invasive meters are commonly used to measure the moisture content of wood substrates.
• Regular moisture testing helps ensure that the wood substrate is within the optimal moisture range for coating application, preventing issues like adhesion failure or cracking.

We recommend the following options:

Wagner Meters Orion® 950 Pin less Moisture Meter

The meter distinguishes itself as the premier choice for multiple reasons, rendering it an essential asset for individuals engaged in woodworking. Its foremost attribute lies in its remarkable accuracy. Featuring a non-invasive pin less sensor coupled with IntelliSense technology, the Orion 950 offers precise moisture readings without compromising the integrity of the wood. This aspect holds particular significance for professionals seeking to safeguard the quality of their materials while attaining dependable moisture measurements.

Mini-Ligno DX/C Moisture Meter

You may choose this meter when dealing with diverse wood types, from domestic to tropical, and need a broad measurement spectrum for both dry and wet lumber. It includes two pin sets for depths of 3/16 and 7/16 inches, plus a port for connecting a hand probe or kiln cables. The vivid red LED display ensures readability in dim settings, and its reliability is backed-up by a lifetime warranty. Excluding batteries and pins, the meter is warranted for two years, making it a top choice for its calibration precision and stability.

Humidity and Temperature Gauges:

• Digital hygrometers and thermometers are essential for monitoring ambient conditions during coating application.
• Maintaining consistent humidity and temperature levels within the recommended range helps achieve optimal coating performance and drying characteristics.
• Digital hygrometers and thermometers are cheap and for the most part reliable, even something for £10 will do the job. However, brands like Extech, Testo, and Vaisala offer reliable humidity and temperature meters suitable for industrial use in the UK.

Heating and Infrared Systems:

Potentially the most expensive and largest upgrade on this list, Infrared heaters or drying systems can be employed to control ambient temperature and accelerate drying times in colder environments.

Proper heating ensures uniform drying of water-based coatings, reducing the risk of defects like orange peel or surface imperfections.

Brands like Cefla and Giardina offer solutions for this, but for the UK market we suggest Shuberts, they offer a wide range of infrared heating solutions suitable for industrial applications in the UK. Including the IR and heating drying systems as well as the tracking rails and everything else you may.

It is possible to get comparable results with a simple drying room with heaters placed in a drying room, with a fan to encourage air movement. If you need help designing this then contact the Anker Stuy team and one of our account managers will happily come along for a site audit.

In conclusion, the drying process of water-based wood joinery coatings in an industrial setting is a meticulous endeavour that demands careful consideration of numerous factors. From the application of coatings to their final curing, each stage plays a crucial role in determining the quality and durability of the finish. By understanding and implementing best practices, operators can optimize the drying process for superior results.

Flash-off periods are essential for allowing solvent evaporation and ensuring a smooth, uniform finish. Drying tunnels provide controlled conditions for efficient and uniform drying, while proper time between spraying coats allows for optimal adhesion and finish durability. Adequate handling times are crucial to prevent surface defects, while full curing ensures maximum performance and longevity of the coating. To facilitate the drying process, the use of essential equipment such as timber moisture gauges, humidity and temperature gauges, and heating and infrared systems is recommended. These tools help monitor and control environmental conditions, ensuring optimal drying conditions and consistent coating quality.

Investing in reliable equipment, such as the Wagner Meters Orion® 950 Pin less Moisture Meter and Mini-Ligno DX/C Moisture Meter for moisture testing, and digital hygrometers and thermometers for monitoring humidity and temperature, enhances efficiency and accuracy in industrial coating operations. Additionally, considering options like infrared heating systems from reputable brands like Shuberts can expedite drying times and improve overall productivity. By integrating proper drying techniques and utilizing suitable equipment, industrial operators can achieve exceptional results in water-based wood joinery coatings, enhancing product quality, performance, and customer satisfaction. As such, prioritizing the implementation of best practices and investing in quality equipment is paramount for success in industrial wood coating operations.