Guitar Reviews 4U - Guitar finishes - Lacquer or Poly? Clear and Paint Guitar finishes explained

 

Guitar Reviews 4U - Guitar finishes - Lacquer or Poly? 

Clear and Paint Guitar finishes explained

So, what's the deal on guitar finishes?

I'll give you an easy guide on the finishes used on guitars 

This special Players edition Gretsch 6120 Nashville in Azure Metallic Blue - 

a great colour against the Gold plated hardware on this Terada Japan Gretsch

Types of Finishes - in the beginning

Historically, wood on musical instruments was protected by finishes such as Shellac or French Polish from the 1800's, before that they were often bare wood. This finish was made from an insect dissolved in Alcohol.

Before the advent of modern finishes in the 20th century, French Polish provided a barrier to protect the bare wood, in those days animal based glues were used in the instrument builds and if an instrument got wet, it could unglue! Nowadays epoxy glues are the standard for most instrument makers.

With the advent of Oil being used commercially for fuels, by-products of Oil were developed by the chemical industry for vehicle finishes into that growing market.

A Terada Japan made Gretsch 6120 in Azure metallic Blue

Cellulose finish - also known as 'Nitro Cellulose'

The auto industry's requirement for weatherproof finishes that were quick drying and tough, led to them being used on musical instruments where there were obvious benefits over French Polish. 

Cellulose (Nitro cellulose) finishes were also found to be easy to apply to wooden parts on musical instruments and were quick drying, unlike French polishing, they were quicker to apply and more durable.

With the American auto industry looking for new sales features, colour paints and special finishes were developed by chemical companies like Du Pont. 

Post WW2 by the late 1940's on, cars featured any number of vivid colours often 2 tone split finishes with a light roof and darker lower body panel colour scheme.

These new finishes found their way into the guitar market, exploited as a sales tool in 1954 by Leo Fender and later by Fred Gretsch.

The drawbacks with Cellulose were fairly simple, it could chip and the dyes used in the paint like Red colours could fade. The paint would often sink into the wood grain over time as the wood expanded and contracted and would crack where extreme temperature changes occurred.

Cellulose takes time to cure harden often a few days before the solvents have evaporated.

The auto industry also had polyester finishes produced, now they use water based Acrylic with UV resistant clear coats.

The synthetic finishes - Acrylic and Polyester Finishes single and 2 part

Chemical finishes like Acrylic and Polyester types are more durable and are the most commonly used finishes today. 

Acrylic is often made as a a single part base to which a thinner is added, it can provide a tough finish.

Polyester (Poly coat) is used in the same style as Acrylic.

The exception is where 2 part paints are used, in both cases of these types above, they use a base product which is mixed with an activator catalyst and then the compound is thinned for spraying.

The catalysts activator makes the paint cure hard and faster, so the finish needs to be sprayed quickly and can cure hard in twenty minutes and the spray gun needs to be cleaned out before the finish dries inside it. 

This finish makes the sprayed guitar able to be handled after twenty minutes as the catalyst has cured the paint through the layers.

Metallic finishes and flake paint finishes are often clear coated to bring out the effect of the inclusions. 

So what is the better finish?

The deal is in how thickly the finish is applied, in the 1970's Fender applied their poly thickly, I had a 1975 Stratocaster and it was about 1mm thick it seemed from the chipped off paint on the body. 

For a chemical coat, the finish doesn't need to be thickly applied.

Most guitars now are thin coated in Poly and that works fine, custom shop guitars go the old Nitro route for the vintage reason they are trying to recreate a modern replica of an old instrument as made. That also means using Nitro you can get paint sinkage and the dangers of paint chipping.

Some of the Gretsch Player guitars have Nitro finishes, the 6118T 140th Anniversary Japan made guitars do, others in their Player range have poly coats.

As long as the finish isn't too thick, then the difference to tone will be negligible, it is the wood and the pickups that can affect the sound - play two guitars from the same batch and hear the difference.

Poly finishes can crack too but is less prone to this happening than a Nitro finish.

Applying finishes

On bare wood, you can use what finish suits your purpose, I have sprayed both paint types on bare guitar bodies, the Poly does take some work to fine sand and polish if you get any texture to the finish but is harder.

I have had 2K Poly from aerosol cans react if you put too many coats on, the problem is the stuff dries like iron!

On bare wood you can use Acrylic primer and a cellulose top but not a cellulose primer and a  Poly top coat.

Choice

For a frequently played modern guitar, Poly finishes are the best choice for durability, Cellulose has its drawbacks as we have explored and it is really down to choice.

The conclusion

The finish if applied sparingly, should not make much of a difference, I've made and sprayed up guitars and used Nitro Cellulose, Acrylic and 2K Paints (not on the same guitar!) and they all work ok as a result. 

There is a lot of 'guff' talked about Nitro Cellulose as king of the finishes, its not always the case that its the best thing 

If you are specifying your own guitar, the choice of finish is yours, but don't necessarily be put off by the Nitro snobbery view!