Waterbased finish for wood furniture

A water-based finish system is a finishing process that uses water-based finishing materials. The water-based system is the opposite of the solvent-based finishing system. The trend toward using water-based materials is increasing for several reasons. The prices of the solvents that tend to rise and the sentiment from the society for environmentally friendly products are two major factors driving this shift. Many people even believe that water-based finishes are the finishing materials of the future.

Today, water-based finishing materials are more advanced and widely available for various applications to meet different finishing requirements. Materials such as stains, glazes, fillers, putties, sealers, and topcoats are now produced in water-based versions, allowing a complete finishing process to be done entirely with water-based products. These materials can also be combined with other types of finishing systems when needed.

In principle, the water-based finishing process is similar to the solvent-based finishes.

The standard water-based finishing process is as follows:

1. Filler (if necessary)

2. Stain

3. Sealer

4. Glaze

5. Sealer

6. Topcoat

However, water-based materials have different properties compared to solvent-based ones, so they require specific handling and techniques.

The Considerations in Using Water-Based Finishing Materials

• Longer Drying Time

Water-based finishes use water as their primary thinner, which evaporates more slowly than solvents. Naturally the water-based finishing material is more difficult to dry than the solvent-based. You have to prepare this condition and provide more room and space to make sure the water-based material fully dries in the finishing process. 

• More sensitive to the weather

The drying of the water-based finishing layer depends on the room conditions, especially humidity and the temperature. On a hot day and in the dry air, the evaporation may occur quickly, and the coating can dry fast. But in the night, or in rainy or cloudy weather, when the room is humid, the evaporation will slow down significantly, making the coating dry very slowly.

To control the drying time and speed up the finishing process, you need to install an oven in the finishing room.

• Requires Better Sanding

When dry, a water-based coating forms a hard and thermosetting film layer that is not soluble in water or thinner. Since then, unlike solvent-based (NC) systems, each new coating layer does not dissolve the previous one. A good sanding between layers is essential to build the good film coating. Poor sanding can lead to film defects such as orange peel textures or visible sanding marks and adhesion problems.

• Better wood preparation

When applied directly to raw wood, water-based coatings tend to raise the wood fibers, making the surface rough. Proper sanding is therefore crucial to achieve a smooth final surface.

• Wood Moisture Content

Water-based materials naturally introduce moisture to the wood surface. During the drying process, this water must fully evaporate. The wet wood will make the drying process of the finishing layer more difficult; the drying will take longer and may cause finishing defects such as a cloudy look, adhesion failure, and fungal problems.

Make sure the wood has properly dried before starting the finishing process.

• Cloudy Appearance

Due to the resin character, water-based coatings tend to produce a slightly cloudy or milky appearance, especially when they are applied in thick layers. The development of the water-based coating technology today has significantly improved clarity; however, water-based coatings still cannot achieve the same crystal-clear finish as nitrocellulose, polyurethane, or varnish systems.

• Waste Management Is Still Required

Although water-based coatings are more environmentally friendly, they still contain chemicals that can contaminate the environment. The finishing process will produce the dust and liquid waste that must be disposed of properly. Standard waste management procedures and safety equipment are still needed.

• Finishing equipment

Water is more corrosive than solvent; thus, the equipment will be at more risk of getting corrosion. The finishing equipment for applying the water-based materials, such as spray guns, tanks, and agitators, should be made from the corrosion-resistant stainless steel or high-grade plastic to prevent the corrosion problem.