how to fix lacquer cracks on a guitar

How To Fix Lacquer Cracks On A Guitar: Fix Guitar Lacquer

Lacquer finish not only makes your guitar gleam beautifully under the spotlight, it also provides a first line of defense for your stringed instrument’s wooden parts. However, much like a shield that can be shattered in battle, lacquer is not immune to damages. This is why it is important for musicians to learn how to fix lacquer cracks on their guitar.

Just like a majority of guitar problems, early detection of any existing crack on your instrument’s lacquer is key to fixing it. Although when the crack is caused by nature and the conditions don’t change, a repeat of the same problem should be expected.

Because addressing lacquer issues will not normally compromise an instrument’s functionality, musicians can also learn how to mend these tiny fractures on their own. But fully concealing the cracks and trying to make the guitar look new again will require more effort and know-how.

For aspiring craftsmen, trying to remove a crack should not be a big problem at all. In fact, these are the challenges that young builders must take advantage of in order for them to hone their abilities further. Turning an ax into a relic is cool and all, but making a guitar look pristine once again is a higher skill level in instrument building and repair.

Conviction and patience, as well as diligent research and practice, are main requisites in handling lacquer cracks. So if you are not confident enough yet, then you may want to entrust matters to your local luthier instead.

Why do guitars need lacquer finish?

Wood is the best material for building guitars, and musicians will always be indebted to mother nature and this amazing gift of hers. But because wood is organic, it is not resistant to moisture, humidity and other harsh weather conditions.

Excessive moisture can cause wood swelling, which can distort an instrument’s shape and render it unplayable. On the other hand, a severely arid climate can make wood brittle, making it prone to cracking.

For ages, guitar builders have relied on humidity stabilizing methods such as sealing wood with paint and lacquer to prevent moisture from entering or leaving through its pores. These wood finishing agents are primarily known for their aesthetic roles, but they also contribute largely to the durability of a guitar.

When it comes to guitar finishes, there are many other options today including oil, polyurethane and polyester. For vintage guitar restoration however, the good old lacquer remains a standard that luthiers follow as part of their adherence to age accuracy requirements.

What causes lacquer cracks on a guitar?

Humidity and sudden temperature or weather shifts are the common culprit behind lacquer cracks, making it a common hurdle for traveling musicians and people living in countries with multiple seasons. 

Finish checking, also known as “weather checking,” refers to parallel or checkered patterns of paint and lacquer cracks usually appearing on guitars with nitrocellulose finishes.

Fixing lacquer cracks and deep scratches

Melting scratches

For more invasive scratches, the surfaces can be melted with lacquer retarder and let them form back together as one nitrocellulose layer. You will need a small paintbrush, almost the size of a pen, to allow easy application of the lacquer retarder. 

Follow the scratches as if you are tracing lines with a pencil and wait for the scratches to start disappearing. Some prefer spraying a wet coat of pure lacquer thinner to cover larger affected areas.

Making cracks disappear

To make the cracks vanish entirely, you will need to completely remove the finish down to the paint by sanding the area with sandpaper. You would then have to match the color of your guitar using the right paint, before sealing it again with lacquer. 

Attempt this only if you have the commitment, since sanding alone can be quite a laborious process. If you are a first-timer, be prepared to make some irreversible errors that may not affect the guitar’s playability, but could leave a lasting scar on the instrument. 

In some cases when the lacquer damage is overwhelming, more radical measures such as intentionally relicing the instrument are done to match the weathered features created by the cracks.

Also keep in mind that retarders are powerful solvents, so make sure that you are working in a well-ventilated area to avoid directly inhaling the fumes.

Finish checking cannot be reversed

Fixing a network of chipped paint and lacquer cracks on a guitar would require the same process required for a single deep scratch. But since you will be working on a wider surface, it will be more time consuming.

Finish checking is impossible to reverse and prevention is the only way to protect your guitar from it.

Final finishing tips

After resealing wood with lacquer, there is a possibility that the new application will look out of place compared to the old finish. A mixture of lacquer retarder, regular thinner and lacquer, known as a “flash coat,” works well in making the new layer look less glossy.

Using an airbrush, spray the flash coat on the area before applying the lacquer. Let it sit for an hour and half, then repeat the process before the last sanding. A combination of lacquer and colortone pigment or liquid stains can be used for the final color matching stage.

Tips on how to prevent lacquer cracks from appearing on your guitar

Storing your guitar in its case at room temperature is most ideal but if that is not possible, avoid letting your instrument sit in the trunk of your car for extended periods. If your guitar has gotten either too warm or too chilled for a long time, don’t take the instrument out of the case immediately. 

Before opening the case, let your guitar stay in there while it adjusts to the present temperature, allowing the hot or cold air to dissipate. Open the lid of your case a couple of inches from time to time and fan the air out, while occasionally lifting the guitar to also release the air trapped at the back of the instrument.

If your efforts fail to prevent cracks from forming, worry not because they are a part of natural aging. In fact, finish checking is considered a form of “patina,” one of the trademarks of weathered axes. Vintage aficionados don’t usually need to know how to fix lacquer cracks on their guitars, they’ll just leave them as they are to add more character to the instrument.

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