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Acrylic Lacquer: A new, low voc clear coating for wood.

    No two finishing lines are exactly the same. Nor are the finishing standards or production goals identical from facility to facility  or shop to shop. To satisfy a wide range of variables relating to application, curing, finish durability, appearance, environmental requirements, “green” sustainability initiatives, and cost, I have been on a constant search for the different coatings out in the market.  To this end we have brought in yet another product for our customers to use.

 

   First of for those who may not be  familure with some of the other products that are generally use in the world of finishing to day.

 

   Nitro cellulose Lacquer, the basics.


Nitrocellulose lacquer is made by mixing fast-drying solvents generally know as lacquer thinners with wood and cotton pulp containing cellulose that has been broken down by acids. A chemist working for the DuPont Chemical Company, is credited for inventing nitrocellulose lacquer in 1921. It was quickly picked up by Henry Ford for his mass-produced automobiles because finished cars could come off the assembly line faster. Not long afterward, nitrocellulose lacquer replaced shellac and oil-based varnishes and became the preferred finish and the industry standard for furniture and cabinet manufacturers.
: nitrocellulose lacquer is relatively inexpensive and dries quickly. The cured resins provide a reasonable protective layer of film over the wood. After the hard film cures, it rubs out well and provides it signature  smooth and silky surface that, Also, because it is an evaporative finish, each new coat of lacquer blends into all the previous coats, making it easy to repair.

The benefits for large and small production shops are considerable

The disadvantages to using nitrocellulose lacquer are also notable. The film yellows as it ages, and it can eventually shrink to the point of causing cracks (often called crazing) to form in the surface. Generally this occurs when you have over built the coating. As well, it does not hold up well in moisture i.e. your kitchen and bathroom.  Best results fore application are by spraying it on; but the overspray is highly flammable. (The same ingredients that go into nitrocellulose lacquers are also used in the manufacture of some explosives.)

Because it dries so quickly, when applied under conditions of high humidity, the lacquer film can trap condensed moisture and cause the finish film to appear cloudy — a problem referred to as blushing. You can overcome that finishing obstacle by adding a slower-drying thinner, called a retarder, which allows the moisture to escape before it gets trapped in the film.

 

  The need for something that doesn’t yellow and has a greater moisture tolerance.

 

Acrylic lacquer

 

  With the increased popularity of using unstained, light-colored woods (such as ash, birch, and maple), woodworkers and furniture manufacturers wanted to avoid the yellowing problems associated with nitrocellulose lacquer as it ages. The finishing industry responded by developing lacquers containing acrylic resins that are truly “water-white.” Acrylic resins go on crystal-clear and stay that way over time. The most widely used of these products is called CAB-acrylic lacquer, made with cellulose acetate butyrate and acrylic resins.: it is best applied by spray equipment, diluted with regular lacquer thinner to obtain the ideal spraying viscosity, and it is fast-drying. Acrylic lacquer is often used as a protective topcoat over colored pigment lacquers to make them wear better and to enhance their resistance to scratches.

Acrylic lacquer dries to a less brittle and more flexible film than that of nitrocellulose lacquer. It is also more expensive. Otherwise, the working properties are much the same

 

The acrylic Lacquer I like:

 

Renner the Italian wood coating manufacture has long provided me with exceptional water based products wanted to get into the American nitro cellulous lacquer market and released their “JL” series 161 VOC acrylic lacquer. Why they had to go and name it like that is beyond me, I would have preferred a snazzy marketing name that I could refer to it as, but, oh well.

 

Here are the qualities of this product:

 

Low VOC, more environmentally friendly and you can reduce it and still be compliant; a word of caution though, over thinning it has caused problems. Suggested total amount you thin it is not more than 5%.

 

Low Odor, It does have a smell but it’s not half as bad as other products.

 

Self Sealing, You don’t need a different product to seal this with. Best practice is to lay down two thin coat and then sand it as if it were a sanding sealer.

 

Non-Yellowing, what else do you say this doesn’t yellow as any regular lacquer or Pre catalyzed lacquer will.

 

Dies Quickly and Hard, I have had a hard time digging my nails in to this stuff, so it is almost as hard as a pre-cat if not harder. As well the acrylic is much more UV resistant,

 

18% Solids, this is a term that a lot of people don’t get but is a very important datum when evaluating a coating. Basically it’s thicker and so you get more square foot coverage. For reference the most common lacquer on the market is 11% solids it’s cheaper but you have to spray twice as much. For most shops there labor is more costly than there materials and so the few buck you save on materials ultimately cost you more in the long run.  

 

 

Cautions I have found:

 

Don’t over thin it. With a lacquer thinner, you can thin it 5 or 10% but not beyond that it will blush and do strange things. In essence when you thin some materials you are trying to increase the viscosity and make it come out of your spray gun better. If you over thin it you begin to alter the chemical make up and that is where you get into problems.

 

Don’t apply it over another manufactures sealer. A, you don’t need to use a sealer and B, the acrylics are not compatible with the lacquers when you do this the nitro-cellulous  in the earlier coating get re-wetted and then reacts with the acrylic resins and does weird stuff.

 

I now have several large manufactures using this product and having great successes with it.

 

If you are interested in this product give me a call if you have had successes or failure with this product I would like to know about them. One of the things I have learned in this business is that you test always. The greatest test of a coating is the test of time. How long did it last and where?

 

Best,

 

Greg  

 

 

 

 

April 22, 2009 Posted by | Acrylic Lacquer, Finishing failures and the fix | , , , , , | 65 Comments