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The two merchandise – each helpful – are fairly completely different.
Dating again a minimum of 100 years, the time period “lacquer” has referred to a non-crosslinking end that thins with lacquer thinner. The commonest sort is nitrocellulose lacquer.
In the late 1980s water-based (or waterborne) finishes grew to become accessible and a few have been labeled “lacquer.” The cause, as one producer confided on the time, was to make woodworkers suppose they have been utilizing a well-recognized end, one that will apply and carry out like the standard lacquer they have been used to. This would possibly make them extra prone to attempt it.
To justify the identify, producers claimed that their water-based end “burned in” like conventional lacquer. That is, every freshly utilized coat dissolved into the earlier coat, creating in impact one thicker coat. So the instance of equivalency was burning in.
To a point that is true. Water-based finishes do bond pretty nicely to earlier coats, however the similarities fairly nicely finish there. In just about each different vital high quality, the 2 finishes are very completely different and may have completely different names to keep away from confusion. Manufacturers, writers and academics ought to cease referring to water-based finishes as lacquer, or water-based lacquer.
The greatest distinction, after all, is that water-based finishes comprise a whole lot of water and lacquer doesn’t. Consider these penalties of water.
■ Water raises the grain of wooden. To get a clean remaining consequence it’s important to sand the raised grain degree and accomplish that with out sanding by means of to the wooden or a stain. Though you also needs to sand the primary coat of lacquer or lacquer sanding sealer, it’s a lot simpler than sanding the raised grain brought on by water.
■ Water-based end is rather more delicate to temperature and humidity than lacquer. There’s not a lot you are able to do to manage the drying price of water-based end aside from management the temperature and humidity in your store, which might be costly. In distinction, the drying price of lacquer might be managed by including lacquer retarder in scorching or humid circumstances and acetone in chilly circumstances.
■ Even in reasonable temperatures and low humidity, water evaporates extra slowly than lacquer thinner, rising the chance of runs and sags. Moreover, most lacquer thinners comprise six or extra solvents that evaporate at completely different charges, additional lowering the probability of runs and sags.
■ Water-based finishes usually comprise coalesced particles that may mess up your end; that isn’t the case with lacquer. So it’s doubly vital to pressure water-based finishes earlier than utilizing.
While these traits might be seen as negatives, water contributes one crucial constructive high quality: decrease odor. Water-based finishes are far much less smelly and worsening to use than lacquer.
A second vital distinction is the resin used.
Lacquer consists of lengthy stringy molecules of nitrocellulose that entangle in liquid kind (like stirred spaghetti in a pot of water) and kind a tough movie after all of the solvent evaporates. This movie can simply be returned to liquid kind by bringing it into contact with lacquer thinner.
In distinction, water-based finishes are composed of emulsified droplets of acrylic or polyurethane resin that come collectively and stick to one another when the water (which evaporates first), then a solvent evaporate. Inside the droplets, the resin molecules crosslink – that’s, kind chemical bonds – however with few exceptions the droplets themselves simply stick to one another. They might be separated with a number of solvents, however with extra issue than with lacquer.
The completely different resins and the best way they treatment account for important variations in the best way the 2 finishes might be manipulated.
■ Lacquer might be repaired invisibly by melting (with warmth) or dissolving (with solvent) extra lacquer into the harm. Because of the crosslinking inside the water-based droplets, nonetheless, there’s often a visual boundary with water-based finishes. This boundary needs to be disguised with coloration, usually a tough activity.
■ Lacquer is simpler to rub to an excellent sheen as a result of the spaghetti-like molecules are simply separated with an abrasive, whereas the crosslinked molecules inside the water-based droplets resist separation. They should be torn aside, making a extra uneven sheen.
■ Also due to the crosslinking, water-based finishes are harder to strip. Lacquer can merely be dissolved and wiped off with lacquer thinner or paint stripper.
■ Water-based finishes are additionally harder to wash from a twig gun. You often should disassemble it to take away all of the end. In distinction, lacquer might be left in a twig gun for every week or longer and nonetheless be completely cleaned when extra lacquer, or lacquer thinner, is sprayed by means of it.
Though the crosslinking inside the droplets might be seen as an issue for manipulating water-based finishes, it’s a bonus for higher abrasion resistance and even some solvent and warmth resistance. This is because of the complete floor space being composed of crosslinked molecules besides the place the droplets stick collectively.
Coloring and filling steps are harder with water-based finishes than with lacquer. For instance, lacquer might be thinned infinitely with lacquer thinner to make toners whereas water-based end can not. Adding an excessive amount of high-surface-tension water causes water-based finishes to bead up.
Also, due to lacquer’s capacity (because of the lacquer thinner) to penetrate by means of layers of coloration (stain, glaze, pore filler) and bond to washcoats or full coats of end beneath, it’s potential to construct a multi-color-step end that has significantly extra movie integrity (resistance to separation on the coloration layers) than might be achieved with water-based end.
As a consequence, factories usually do their ornamental steps with a solvent end, then topcoat with water-based end to adjust to VOC legal guidelines.
Finally, one of the important variations is coloration, or lack of it, the end provides to the wooden. Lacquer provides a heat orange coloring whereas most water-based finishes add no coloration.
The orange coloring warms darker woods corresponding to walnut, cherry and mahogany in distinction to water-based finishes, which deaden the colour (except you apply a stain). On the opposite hand, most water-based finishes preserve the white coloring of woods corresponding to maple, birch, ash and pine, which I discover engaging.
I hope I’ve made the case that water-based end could be very completely different from lacquer and shouldn’t be referred to as lacquer. PWM
Bob is a contributing editor to this journal, and writer of “Flexner on Finishing,” “Wood Finishing 101” and “Understanding Wood Finishing.”
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