Why we use a Lacquer or Acrylic Urethane Wood Finish & NOT a Paint Product on wood?
Wood is always breathing, expanding and contracting with the humidity changes in it's environment, any coatings applied should also have the ability to move with the wood as well as allowing the finish to breath. We all know how quickly the wood on a Deck can move and degrade, Outdoor conditions are the extreme, however the same factors are at play only on a smaller scale. The movement varies depending also on the type or species of the wood, the denser the wood the less movement there is. As wood expands and contracts the finish has to be flexible enough to move with it, should the finish/paint not be able to move as required fine cracks will begin to appear along wood grain patterns, this would be most evident when the wood is Oak as it shows a considerable amount of exposed grain. Eventually the moisture in the room will get into those cracks and begin to cause the paint to flake off. This can be accelerated when steam or moisture are present like in a bathroom, kitchen or Dining Room Table Tops.
'Paints that dry by simple solvent evaporation and contain a solid binder dissolved in a solvent are known as lacquers. A solid film forms when the solvent evaporates, and because the film can re-dissolve in solvent, lacquers are not suitable for applications where high chemical resistance is needed. Classic nitrocellulose lacquers (oil based) fall into this category. The newer waterborne Acrylic Urethanes are much higher in moisture & chemical resistance and quickly becoming the standard finish for manufacturers due to the Low VOC content and fast drying ability they have.
Performance varies by formulation, but lacquers generally tend to have better UV resistance and lower corrosion resistance than comparable systems that cure by polymerization or coalescence (paint).
Latex paint is a water-borne dispersion of sub-micrometre polymer particles. Latex paints cure by a process called coalescence where first the water, and then the trace, or coalescing, solvent, evaporate and draw together and soften the latex binder particles and fuse them together into irreversibly bound networked structures, so that the paint will not redissolve in the solvent that originally carried it. The residual surfactants in paint as well as hydrolytic effects with some polymers cause the paint to remain susceptible to softening and, over time, degradation by water.' - Wikipedia
It is even possible for the wood on the underside of a solid wood table to draw in moisture and bring it right up and under the finish on the other side. If you have ever seen a piece of wood that has cupped itself and twisted, this is due to the varying degree of moisture that is in the wood, certain grain patterns allow for more movement then others.
The general rule of thumb is that it is always best to "Do to one Side, What you do to the Other Side", This is most important when dealing with solid woods. Veeners/plywoods and proper construction techniques reduce the need to have equal finishes on both sides, however it is 'always best' to at least seal any exposed wood surfaces.
It is important to know what type and how much finish should be applied to the different wood furniture available, Lacquer is a wonderful wise choice when your looking for long lasting durability, a fine smooth finish along with resistance to chips and many household chemicals and beverages.
The furniture industry relies on Lacquer and does Not use paint for indoor wood furniture.
Nitro-Cellulose Oil Based Lacquer's are highly volatile, considered Toxic and should only be used by Professionals in a Commercial Setting where proper ventilation is crucial. Never try to spray these lacquers in your home or garage. Notice the word 'Nitro' in the name, the glycerol ingredient found in nitro gliceren is used to make this type of lacquer. A spark can ignite the fumes or vapours quick and easy.
Read More About the Process: The biggest concern with lacquer is water resistance, whether hot or cold water. Various types of lacquer's can be used depending on the circumstances, there are pre catalyzed or post catalyzed lacquer's available whether they are oil, acrylic or low VOC water based. Lacquer is used on interior wood surfaces. There are what they call Automotive Lacquers available that are specifically made for use on metal intended for the outdoors, these offer complete sealing of the metal surface it is applied to.
Paint is thicker and can tend to build up in corners and grooves leaving areas that are not even. Lacquer is sprayed on in coats that are 1-2 mil in thickness, the end thickness is usually 4-6 mils. This provides a great bond and the ability for the wood to still breath through the finish. The finish looks thinner and professional, more so then a spray painted paint finish.
Lacquer also bonds to itself better then paint bonds to paint. This is helpful when one wants to update a colour on a lacquer finish. Lacquer when applied over lacquer has a softening or melting ability that allows it to fuse itself better, this tends to lead to a stronger finish that moves together along with the wood. Paint tends to layer itself more, this requires more sanding and primers in order to get good adhesion. We use lacquer sealers in substitute for primer and lacquer replaces paint.
We 'Spray Paint Furniture' making it look like new again, using long lasting lacquer equal or better to the original factory finish.
The DIY - Paint it at Home person can find some 'paint' spraying tips & techniques here: Furniture Paint Spraying Techniques Lacquer spray painting techniques vary by type, Water based lacquer's are more difficult to spray than Oil Based lacquer's.
Water Based Lacquer or Acrylic Urethanes are heavy products so applying it to various styles of furniture varies considerably. Unlike paint, the tints can effect viscosity and the approach to spraying is crucial. Flat surfaces are considered to be straightforward (once you find the correct air to flow ratio, not all spraying guns are equal) A new approach is required where ever there are spindles, carvings, moldings or any area that requires using a different angle in order to get that even spray coverage , it takes a great deal of patience to spray these styles.
If you have furniture that will not be under regular everyday use like chairs, table tops or cabinet doors, using high quality paint to spray paint it will give you new looking reasonable results. Any high traffic items or pieces that are near water or steam should stay away from paints, especially on solid woods, you have more flexibility when veneer's are involved. Keep in mind that Lacquer's tend to have a longer warranty period when applied according to the manufacturer's method's. My research shows that lacquer has 2.0 to 3.5 (times longer) warranty periods then the average name brand paints when used on wood furniture. 15 to 25 years depending on the type of lacquer and the method used to apply it. There are brushable lacquer's available that can produce results as well. Follow instructions, do some testing and with some patience and the use of proper equipment you can mimic a pro and spray it to look like it was when new too!