Experiences in Waterborne Finishing

I want to share some experiences I’ve had in adopting the use of waterborne finishes. Hopefully, some of my encounters will help those of you who consider exploring this most challenging aspect of green practices.

About five years ago, I was working for an architectural woodworking company that had embarked on a campaign to become green. As Director of Research and Development, I had the privilege of working with a consultant from the Rochester Institute of Technology. We examined the all aspects of production looking for opportunities to improve not only the environmental impact of the operation but the health and safety of the workers, as well.

By far the biggest and most challenging opportunity was in the finishing department. Finishing is where the largest amount of hazardous waste is produced. It’s also a process that impacts the long-term health of the workers in a very significant way. We considered low-VOC conventional finishes but due to the ambitious nature of our task, we turned to waterborne finishes as the most effective solution. We began to examine products from various manufacturers; I would evaluate the workability of each product while she (the consultant) evaluated the health and environmental aspects. We proceeded enthusiastically, finding and testing products from dozens of manufacturers, both domestic and European.

Since the products that the company produced included a lot of open pore woods such as mahogany, walnut, and oak, we needed to find a finishing material that would “bridge the pores” in a manner similar to conventional finishes when sprayed. Finishes that don’t adequately bridge the pores leave the pores severely open and have a “crater” effect where the finish builds up around the open pore. The result is a finished product that looks like a plastic imitation of wood. For almost six months, all the products we tested ended up with this unacceptable appearance. Finally, we found products from two companies that succeeded in bridging the pores adequately. However, due to scheduling and other concerns, implementation was not carried out.

I continued testing on my own as part of my consulting and furniture restoration business. For refinishing furniture that was not antique, I had been using conventional lacquer. In order to adopt the use of waterborne finishes, I knew that I had to accept some compromises. A certain degree of clarity would be sacrificed since waterborne finishes can’t achieve the clarity of conventional lacquers. Also, more work would be required to achieve a smooth finish. Waterborne finishes tend to leave a rough surface “off the gun” so hand rubbing would need to be more extensive.

When I started using these waterborne finishes on actual jobs rather than just samples, additional problems revealed themselves. Since my business also required finishing of open grained woods, I continued to use the products that bridged the pores. Primarily, I pursued the use of the product that had the greater clarity. As I proceeded, I found that it failed to hold adequately on vertical surfaces, resulting in sags and runs. The only hint I got was that there may have been trade-offs in the formulation of the finish but I got no definitive answer.

Another revelation occurred in the middle of finishing a kitchen. I had previously sprayed two coats of waterborne finish, sanding in between with 320-grit non-stearated sandpaper. When I sprayed the third coat, the finish was rejected and pushed back from large areas of the surface. Although the manufacturer had seen this phenomenon before, no definitive explanation was ever provided.

Again I encountered a sobering situation when I finished a table top with a waterborne finish that was certified to be acceptable for kitchen use. Several weeks after I delivered the table, water had dripped on the surface and went unnoticed for two or three days. The finish in that area had completely dissolved.

After several years of using waterborne finishes, surprises still came up that needed to be addressed. I’ve managed to work through them but at a significant cost. Not being a finish formulator, it’s impossible for me to fully understand why these things happen or to make sure they don’t happen again. Manufacturers don’t always have the answers. Certifications and other independent test results have proven inadequate. Although I haven’t entirely given up on waterborne finishes, I finally had to go back to using conventional lacquer.

While waterborne finishes work for some woodworkers, I don’t feel that the technology has yet been developed adequately to address the needs of woodworkers in all situations. Hopefully, it will be here soon. Along with this development, I hope to see access to information that addresses specific problems encountered in the real world along with realistic solutions. Without this, I don’t see how regulators and certifiers can reasonably expect woodworkers to adopt waterborne finishes as a standard.