Why Water-Based Paint Matters in Office Furniture: A Complete Guide

Eco-friendly furniture has long been popular with consumers, but when it comes to whether furniture is finished with oil-based or water-based paint, many people don't fully understand the difference between the two.

What is water-based paint?

Any coating that uses water as its solvent or dispersion medium can be called water-based paint. Water-based paint is harmless to the human body, doesn't pollute the environment, and produces a full, crystal-clear, flexible film. It is also water-resistant, wear-resistant, aging-resistant, yellowing-resistant, quick-drying, and easy to use.

The biggest difference between water-based and solvent-based coatings is that water-based coatings use water as the dispersion medium, while solvent-based coatings rely on organic solvents. Compared with solvent-based coatings, the environmental advantages of water-based paint are striking: its VOC emissions are roughly one-tenth of those of traditional solvent-based paint. According to relevant statistical analysis, of the main sources of PM2.5, vehicle exhaust accounts for 30%, VOC emissions account for 21%, and residues from other daily power generation, industrial production, and similar combustion processes account for 49%. Of those VOC emissions, roughly 18% come from solvent-based paint.

As it happens, beyond cost, the more decisive reason water-based paint has yet to be widely adopted is that at the point of sale, consumers still find it hard to identify and judge the respective merits of water-based and oil-based painted furniture. In principle, the two solvents produce different volatility profiles: oil-based paint has a stronger formaldehyde smell, while water-based paint is virtually odorless, so consumers could tell them apart on their own. But industry insiders point out that if paint manufacturers use masking agents, the formaldehyde smell of oil-based paint gets covered up, making the two very hard to distinguish. As a result, the more expensive water-based painted furniture can't compete with oil-based painted furniture, and many furniture companies balk at "going water-based."

Types of water-based paint, and their pros and cons

Water-based paints mainly include water-solution (water soluble) and water-emulsion (water emulsion) types, with the water-emulsion type in relatively wider use. Water-based paint is generally divided into one-component and two-component formulas. One-component paint can be thinned with clean water or applied directly; two-component paint requires adding a water-based curing agent, stirring thoroughly, then thinning with clean water before application.

1. One-component water-based wood paint

Advantages: With advances in water-based wood paint technology, one-component water-based paint performs better and better. Its film is flexible, highly transparent, quick-drying, and well-adhered, with a fine, soft, attractive finish. Fullness of film, water and chemical resistance, hardness, and scratch resistance have all improved markedly, meeting the coating needs of vertical furniture systems such as cabinets, wall panels, bookshelves, display cases, and beds. One-component water-based wood paint is now mature in pine children's furniture and outdoor coatings, already holding more than half of that market share. As water-based paint companies focus on promoting and developing water-based door and window coatings, the qualities oil-based paint lacks — breathability (permeable to air but not water); high elasticity and toughness; long-lasting weather resistance — can protect wooden doors and windows far longer against the dual tests of indoor and outdoor environments. Its application processes and results increasingly meet the needs of wooden doors and windows, and water-based coating of solid-wood and aluminum-wood windows is now entering a period of rapid growth.

Disadvantages: Because water-based paint uses water as its thinner, it changes the moisture content of the wood during application, and shifts in moisture content can cause swelling, bending, and warping — which makes water-based paint harder to apply. In addition, water-based paint suits thinner films with open-pore or semi-closed finishes, so sanding during processing must be more meticulous. That demands a high level of craftsmanship from furniture makers.

Since one-component water-based paint forms its film through natural evaporation of water, it has certain requirements for application temperature and humidity. Its film dries slowly in practical terms, its degree of cross-linking is low, the film it forms isn't dense enough, and the final film quality can't be well guaranteed. As a result, one-component water-based paint offers limited hardness, scratch resistance, and chemical resistance, and weak sealing power — so it is not suitable for furniture that demands high hardness, such as flat-surface systems like tables and floors. It also struggles to seal in the oils of resin-rich woods such as pine.

For the furniture industry, the quality of one-component water-based paint currently varies widely, and the results can differ enormously. Some low-grade, inferior water-based products have distorted the market's understanding and development of water-based paint. But as the mainstay of the water-based category, one-component paint will see rapid development from raw materials to application, meeting coating needs and gaining ever-wider use.

2. Two-component water-based wood paint

Advantages: Two-component water-based wood paint offers far better all-around performance than the common one-component kind, because a curing agent is added on top of the one-component base to assist film formation. Since two-component water-based wood paint cures through a chemical reaction, its film performance improves dramatically — especially water resistance, chemical resistance, stain resistance, anti-blocking, hardness and scratch resistance, heat resistance, and wear resistance. Film hardness can reach 2H, rivaling traditional PU oil-based paint. It can be used for flat-surface furniture coatings, meeting demands for hardness and scratch resistance. It can also serve as a sealing primer paired with one-component water-based wood paint, effectively sealing in wood oils, tannic acid, and more.

Disadvantages: While the curing agent boosts the film performance of two-component water-based paint, it has some impact on the paint's eco-friendliness. Although water-based curing agents likewise contain no formaldehyde, benzene, or similar substances, they do add some VOC emissions and odor. At the same time, coating costs for two-component water-based wood paint are at least twice as high as for the one-component kind. For furniture companies, two-component water-based paint can satisfy both environmental performance and furniture coating requirements — but the added cost is hard for them to accept. That said, coating costs can be effectively controlled: a sensible pairing of processes can meet coating needs while keeping costs in check.

As an emerging force in the coatings industry, water-based paint will, in China, ultimately be driven into full use by consumers' demands for a healthy home. If furniture companies ignore consumers' preference for environmental safety and lag in transitioning, they will inevitably lose competitiveness in the future market — and may even lose their place in it.

In recent years, China has rolled out a dense series of environmental policies, including a consumption tax on coatings. Notably, after the policy took effect on February 1, 2015 imposing a 4% consumption tax on coatings with VOC content above 420 grams/liter (inclusive), traditional solvent-based industrial coating companies have been racing to transform toward water-based, powder, and other eco-friendly directions. Facing ever-stricter environmental policies, whether raw material suppliers, coating manufacturers, or coating equipment makers, all are accelerating their transition around eco-friendly products such as water-based coatings — and water-based coatings are headed for major growth.