Something about the lacquering process

 In the seventies of the past age it was quite common to use

polyurethane finishes. They are quite hard but were most of the

time only used on the lower price range instruments. In Japan

often the addition "catalyzed" (polyurethane) is used. But for 

the more high end instruments the so called "Cashew Oil" 

a oil based polymerized varnish. Wether if the cashew nut is 

responsible for its' name I dare to doubt that. It has

everything to do with the cashew nut color!

Something about lacquer and more....

Polyurethane and lacquer are two of the common wood finishes used to add a smooth and glossy coat. The other closely-linked finishes include shellac and varnish. Polyurethane and lacquer are oftentimes used interchangeably mainly due to the confusion of their identities. There is a significant difference between these finishes, and this article unfolds that.

What is lacquer?

Lacquer is a common wood furniture finish preferred by woodworkers among other finishes. This has to do with its ease of applications and quick-dry as it is a thinner finish. It provides a smooth and glossy finish while remaining durable on the wood. Again, it is resistant to damages as it penetrates the wood surface. Applying lacquer requires a high-volume, low-pressure sprayer in an adequately ventilated room.

There are basically three lacquer variances, viz. acrylic lacquer, water-based lacquer and nitrocellulose lacquer. Irrespective of these variances, lacquer is generally durable and quick-drying.

• Acrylic lacquer – Acrylic lacquer is well-known for its resistance to causing yellow color on wood finishes as others do. Instead, it leaves a clear color. Among other types of acrylic lacquers, there is the CAB-acrylic lacquer – a finish that is less brittle and more flexible. It is furthermore resistant to wear and scratches. However, it is costly. Applying this finish requires the spray if you combine it with a thinner agent.
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• Water-based lacquer – this lacquer finish is less toxic, odorless and more durable than other oil-based finishes. Comparing it with nitrocellulose, it can last for an extra period of 5 years. It also dries faster and costs lesser.
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• Nitrocellulose lacquer – the finish is characterized by its evaporative property. It was first used on automobiles and later found its way to wood furniture. It enhances the color, and so it can be used on light or dark wood furniture. Moreover, it is resistant to damages while giving your wood surface a protective film. Nitrocellulose lacquer should be applied with caution as it is highly flammable. It requires a well-ventilated room. Also, do not overspray it.

If lacquer requires repairs, it is easy to accomplish that because it is thin and thus blends effectively with previous coats. Polyurethane on the other hand may require sanding to enhance adherence of successive coats so (wet) sanding in between with a very fine grid is necessary.

What is polyurethane?

Polyurethane is also a popular wood finish applied to provide a thick and glossy finish. It is basically a plastic in a liquid form until it dries. Polyurethane, unlike lacquer, is thick and not easy to apply with the spray unless a thinning agent is combined with it. The finish comes in water-based and oil-based. These variances typically differ in the dry time and composition, but are commonly durable.

Oil based polyurethane 

This one carries the identity of polyurethane finishes. It is durable but dries slower. It can take up to 24 hours to dry hence professional woodworkers often prefer lacquer or water-based polyurethane over the oil-based one. However, the oil-based polyurethane is more durable than water-based ones. And, it can withstand heat abuse, and so using it on kitchen tabletop is the best strategy.

The oil-based polyurethane imparts odor and it is toxic. Users need to use it in an adequately ventilated environment. The downside of it is that it cures after a long time. Once it is applied incorrectly, it has to be sanded because successive coats will not adhere firmly to the previous one. Unlike the lacquer finish, polyurethane does not penetrate the wood. It only gives a surface coat that is durable. The other downside is that the oil-based one can leave a yellowish color on light wood products.

Key differences between lacquer and polyurethane

Quality

Despite being available in variances, polyurethane is more durable. It is thick and leaves a strong coating. Lacquer is thin and penetrates the wood surface. It is also durable but susceptible to scratches and discoloration after some time.

Ease of application

Polyurethane is thicker and needs a brush to apply it. There could be some brush marks on your surface after applying it. You need a fine brush to prevent that. With the lacquer, you need the high volume low pressure sprayer to spray it on your target. It applies evenly even though the spray is expensive than the brush. So, in comparison, it is easier to apply lacquer than it is with polyurethane.

Summary of Lacquer Vs. Polyurethane

• - Polyurethane is thicker than lacquer and dries after a long time
• - Lacquer is thinner and dries quicker
• - Polyurethane is available in water-based and oil-based 
• - Lacquer is available in acrylic, nitrocellulose and water-based
• Lacquer is easy to apply multiple coats because it dries quicker and the coats adhere to each other easily
• Polyurethane coat needs sanding for multiple coats
• Lacquer is applied with the high pressure low pressure sprayer whereas polyurethane is applied with the bristle brush. If a thinner is added, polyurethane can be applied with the spray too
• These finishes are both durable but polyurethane is more durable.

About Catalyzed Polyurethane.

It is equally or more water resistant than oil-based polyurethane.

Besides that it is a sprayable finish and can be built up and act as 
its own sealer. It allows easy repairs with minimal turn around time.
If you don’t mind a slightly plasticy look it holds up well.