Water-based finish and HVLP spray-gun technologies owe their existence to the clean-air legislation passed since the 1960s. Both technologies made their commercial appearances in the late 1980s â€” each with a goal of reducing solvent emissions into the atmosphere.
HVLP (high volume low pressure) technology showed up originally in the form of portable turbine-air-supplied spray guns that produce a soft spray with up to a third less bounce-back (and resulting waste) than high-pressure guns. By the mid-1990s, manufacturers of high-pressure, compressed-air-supplied spray guns had modified their guns to produce the same soft HVLP spray and still atomize as well as turbine and high-pressure guns.
Thus, with both turbine and compressed-air HVLP guns producing the same high quality results as high-pressure guns, there was every incentive for finishers to switch because of the significant cost savings in finish materials. Almost everyone now uses HVLP, and even among those who don't, there's no vocal resistance.
HVLP has won the day, and we, as finishers and manufacturers, should be proud of ourselves for adopting this pollution-reducing technology.
But the same can't be said for water-based finishes. There's still a lot of resistance in small and medium size shops, even though there are some clear incentives to adopt these finishes. These include health benefits (avoiding the noxious fumes produced by lacquer thinner), lower insurance costs and protection of the environment.
It's clearly possible to make the switch. If you doubt this, simply read any of the numerous stories in trade magazines about shops that have done it.
A comfort level
So why is there still so much resistance to water-based finishes when there is essentially none to HVLP technology? Why, for example, do so many shops in the most strictly regulated part of the country, Southern California, go to such great lengths to avoid switching â€” even to the point of bootlegging non-compliant solvent finishes in from neighboring states at the risk of heavy fines?
I believe there are several reasons, starting with the basic conservative nature of finishers who resist any change when what they're doing is working. Then, there's the less-than-helpful marketing practices of some of the water-based finish suppliers.
Getting consistent results in a production situation is tough. It's not the macro differences in finishes that are the problem: whether to use nitrocellulose lacquer or conversion varnish, wiping stain or non-grain-raising (NGR) dye, glaze or toner. It's the micro differences in products of the same type that can drive finishers crazy.
Even the smallest formulation changes by a manufacturer or a change from one brand of stain or finish to another can result in days of adjustment to get everything working right again. Weather changes also cause problems that need to be resolved.
Bottom line, it takes a great deal of time and effort to become familiar enough with a finishing system and a set of products to minimize problems. Once a finisher has achieved a level of comfort, it takes an awful lot of prodding to get him or her to change anything voluntarily.
The need to adjust
HVLP doesn't feel all that different from high pressure. The necessary adjustments to achieve smooth results without orange peel or runs aren't very great, so finishers made the switch relatively painlessly. But the adjustments necessary to achieve good results using a water-based system instead of a solvent-based system are considerable:
***Water-based finishes run and sag on vertical surfaces far easier than finishes that thin with lacquer thinner.
Though formulators have managed to reduce some of the tendency, they will never duplicate the run resistance of lacquer because of the nature of lacquer thinner. It's made of six or more solvents that evaporate at different rates, causing the finish to seize up quickly on the surface while still retaining enough solvent for the finish to level out. With water-based finishes, the finisher has to adjust his or her spraying technique to compensate for its propensity to run.
***Water-based finishes raise the grain of the wood.
Again, formulators have managed to reduce this tendency somewhat, but it will never reach that of solvent-based finishes. Most finishers have learned to ignore raised grain by "burying" it under the sealer coat and then sanding the surface level; but more sanding is required so there is greater risk of sanding through.
***Water-based finishes are more sensitive to weather changes than solvent-based finishes.
There are widely available and well understood thinners that can be added to solvent finishes to compensate â€” primarily lacquer retarder and fast lacquer thinner. But there are no established, industry-wide, problem-solving thinners available for water-based finishes. Some suppliers provide solvents that help, but most don't. More on this later.
***Water-based finishes don't have the same intercoat adhesion ("burn-in") characteristics as most solvent-based finishes.
Formulators have improved the adherence of water-based finishes, but it's doubtful they will ever achieve that of solvent-based finishes because adherence depends so much on the ability of a solvent to penetrate and soften the surface of the existing coating. Finishers have to adjust their procedures to ensure good bonding and avoid "ghosting," or layering, when rubbing.
***Water-based finishes have a slower dry time than solvent-based systems (not counting varnishes) because of all the water that has to evaporate out of the finish.
Ovens can be used to speed up the drying (they can also be used with solvent-based finishes, of course), but ovens introduce problems of their own, including bubbles. Finishers have to adjust to the slower dry time.
***Water-based stains often dry too fast for even wipe-off, especially on large surfaces.
Solvents can be added to slow the drying, but these aren't widely available or understood, and adding a solvent changes the intensity of the color, requiring another adjustment. Finishers have to adjust their coloring procedures to take into account the fast drying of water-based stains.
***Spray gun clean up with water-based finishes is much more critical and difficult than with lacquers (but not more critical than with conversion varnish).
Lacquer can simply be rinsed out by running thinner through the gun and hose, if there is one. But spray guns often have to be disassembled and cleaned when water-based finishes are used. Running warm water, or even a solvent thinner, through the gun is not the sure cleaning procedure it's often made out to be. Finishers have to adjust their gun-care procedures.
This is not a complete list of adjustments that have to be made. For example, it doesn't include the critical minor adjustments in gun speed and distance necessary when spraying any new finish to get an orange peel-free surface. Clearly, finishers are faced with a considerable task when switching to water-based finishes. It's no wonder there is resistance.
The situation is further complicated by the objection of many to the appearance of water-based finishes on some woods and the absence of a cost-benefit incentive such as that associated with HVLP. In fact, contrary to the claims of many suppliers, there is usually a significant cost increase, even factoring in the higher solids of water-based finishes and possible reduced insurance costs.
I believe some of the resistance to switching to water base is caused by manufacturers, who over-hype their products, especially the small companies that sell only water-based products. The over-hyping is not as common among companies that sell a variety of solvent and water products; these companies don't care as much which product you buy, as long as you buy it from them.
The most obvious cases of over-hyping are the continued claims some companies make of improvements â€” often referred to as "generational" changes â€” that now make their water-based finishes equivalent to solvent-based when, in fact, the changes are just at the margins.
Over the last decade, finish companies working together with raw-materials suppliers have made noticeable improvements in durability, leveling, adhesion and reduced bubbling. But all of the problems listed above still exist, and finishers have to adjust to them. There is a limit to what can be done to make a finish not act like water when, by its very nature, it does contain a lot of water.
There was also hype surrounding turbine HVLP when it was introduced, but it tended to be more industry-wide rather than supplier-specific. For example, there was an often-repeated claim that the hot air produced by turbine HVLP spray guns reduces or even eliminates blushing in lacquer. This isn't true, because the air doesn't contact the finish until it has already left the spray gun. The atomization causes the finish to cool much more rapidly than the warm air can heat it.
In contrast, consider the claims of some water-based suppliers that their finish "burns-in" to the coat below, making the product equivalent to lacquer. Well, as mentioned above, the burn-in isn't equivalent. But this isn't the issue. Even if the burn-in were equivalent, the finish still isn't lacquer. There are many other significant differences, including the propensity to run on vertical surfaces, grain raising, drying time and ease of repair, that separate the two finishes and are ignored in these claims.
Some manufacturers also tend to muddy the understanding of water-based finishes with their naming practices. You can find water-based finishes that are essentially the same (in that they contain water and cure in the same way) labeled lacquer, varnish, polyurethane, pre-cat, etc. In some cases this is so blatant you have to look for the clean-up solvent listed in small print on the back of the can to learn that the finish is really water based.
This level of attempted deception â€” that is, trying to make you think the finish is something else â€” doesn't exist with other professional finishes.
What can be done?
We are all in favor of protecting the environment, and water-based finishes help do this. But clearly, the present strategy of persuading shops to switch isn't working. Few of them are willing to take on the effort and expense necessary.
I suggest two changes in the marketing of water-based finishes that may make them more acceptable: promote the health benefits more than the environmental benefits, and create an industry-wide standard for naming and application procedures.
Small cabinet and furniture shops rarely have an exhaust set-up that totally eliminates solvent fumes. Solvent finishes, for example, out-gas for hours after each coat of finish is applied, but the exhaust fan is rarely left running during this time. As a result, the noxious fumes usually filter through the shop, irritating employees to the point that they don't feel all that well at the end of the day.
Water-based finishes don't out-gas anywhere near the quantity of noxious fumes, so the workplace becomes a healthier environment. This is an advantage all finishers can understand and appreciate. Almost every finisher I've ever talked to who has switched to water-based cites how much better he or she feels as a result.
A big factor that makes solvent-based more user-friendly than water-based is the industry-wide understanding of the finishes. There's virtually no formal education available for finishers, so most learn what they know primarily by trial and error. When suppliers make exaggerated claims for their products (and sometimes misname them as well), finishers become frustrated. Much of the incentive they may have had to switch is lost.
Because they are inherently resistant to change anyway, many just continue using what they are accustomed to, even to the point of breaking the law to do so.
It would be so much better if the water-based suppliers got together in some way and standardized the naming and the solutions to the common problems, including making the solvents that solve problems (propylene glycols and glycol ethers) widely available â€” such as lacquer retarder. The goal should be to make the knowledge needed to successfully apply water-based finishes as widely known and accepted as it is with lacquer.
Instead of competing to take market share from others, adopt a policy of raising all boats.
Bob Flexner will present a two-hour seminar, "Cabinet Grade Finishing for the Small Shop," at IWF2008 in Atlanta on Friday afternoon, Aug. 22.