Common Finish Issues
Lacquer Checking / Crazing
This is an extremely common, somewhat expected condition on older instruments with lacquer finishes. Checking will vary according to the extremes the instrument has been through. As an instruments wood expands and contracts with moisture content stress is placed on the finish.
Heavy finish checking /crazing
The lacquer itself is put thru allot of stress as this takes place and the finish may develop checking/crazing is a result of this movement. Checking looks like very fine finish cracks running in all directions.
Extreme and sudden temperature changes can also cause finish checking, regardless of the instruments age.
Can I avoid checking?
If you travel with your instrument and it is subject to severe temperature changes, you should allow it to acclimate to room temperature before opening the case. When instruments are shipped to me they are left unopened until I am sure the contents have had the opportunity to warm/cool to room temperature slowly.
You should also insure you are properly humidifying your instruments to avoid sever dryness. See my humidity article for more information.
Can you repair finish checks? Because checking is a common occurrence on vintage instruments most should avoid refinishing as it is likely to happen again. An additional deterrent would be the negative effect on value.
Instruments finished in nitrocellulose lacquer not only tend to craze with greater ease than the newest catalyzed finishes but they also yellow with age. An instruments finish can consist of a color coat and clear top coat or simply a clear coat.
With age this clear top coat begins to turn yellow. That means a white guitar may eventually turn yellow and, since blue and yellow make green, older blue instruments can eventually turn green. This phenomenon is a simple fact of life and a natural occurrence with aging lacquer.
While it's true that UV rays may accelerate the process (just peak under a pickguard), nothing can be done to stop nitrocellulose from yellowing. In fact, like crazing, it is a common and expected occurrence.
Can you sand off the clear coat to remove the yellowing? As simple as that may sound the answer is no. Trying to sand off just the top clear coat and not damage the color is a lesson in futility.
That being said, when I was young I attempted to sand off a refinish color to reveal the original finish on a vintage Fender Strat. What I found after days spent removing small amounts of finish was that the original coat had been sanded thru in areas as it was prepped for the refinish. Futility only a do it yourself er would attempt!
Soft, Gooey Finish
Lacquer is the most common finish used on vintage instruments and while it has great properties for touch up it can be damaged with certain solvents.
Lacquer is a solvent based finish and can be damaged by contact with acetone and lacquer thinner. It can also be damaged with prolonged contact with water and denatured alcohol.
One reaction that many are unaware of is lacquers nasty reaction to prolonged contact with vinyl. Vinyl will soften lacquer to a point that it will roll up under your fingers. Refinishing of the effected area is necessary.
Peeling Paint (Delaminating)
Different manufacturers have had issues with de-laminating finish at different times. De-lamination occurs when the top coat can not adhere to the underlying sizing or sealer. Much like the white Dodge's we see driving around with large patches of exposed gray primer, the top coat let's loose and chips off with little effort.
Because this is an adhesion issue, overspraying without stripping to bare wood often results in a repeat. The surface must be re-prepared for refinishing.
Cloudy White Finish
Finish clouding on peghead
of Alvarez guitar.
Clouding refers to a milky white coloring that makes the clear coat far less transparent and foggy.
I have only witnessed this phenomenon on inexpensive poly finished instruments.
Due to the time and cost involved to strip and refinish one of these instruments it is a condition most are forced to live with. Because the clouding is in the finish, buffing and polishing have no effect.
This is not usually seen when the instrument is new but develops over time. While I have ideas as to the cause I do not know for certain.
Acoustic Guitar Repairs
- Action / Set Up
- Bridge Plate
- Bridge Pins
- Buzzing - Noise
- Care / Maintenance
- Convert Rt. to Lt.
- Fret Replacement
- Fret Types
- Neck Damage / Issues
- Neck Angle
- Neck Resets
- Part Glossary
- Strap Buttons
- String Changing
- String Choices / Effects
- Truss Rod
- Tuning Machines
- Tuning Troubles