Finish crazing causes?

This Kamaka Baritone (White Label) is covered with finish crazing. What is the reason this occurs and what should be done to avoid it?

Bad lacquer in my experience....

Cold checking?

nitrocellulose + real cold weather = checking

If the uke does have nitrocellulose lacquer for a finish, this kind of crazing or checking is almost always caused by temperature and or humidity changes, in some cases extreme changes in a short time period. The finish cracks because the wood is moving under the finish, and while the wood can adapt to the temp changes without suffering any damage, the finish does not, especially if the finish is older. This happens with older instruments all the time and I know of no lacquer, not matter what the quality, that won't suffer the same over time. This is also true of shellacs and poly finishes. You can lessen this effect by taking care of the instrument from day one and avoid weather extremes. It can be repaired but we won't get into that on this thread.

Thanks for the replies. Fortunately, I don't own this instrument, but was considering buying it until the close-up photos showed the crazing problems. I don't know what Kamaka was using for a finish back then. I was curious what caused it and ways to avoid it in anything I may build. Thanks again.

Tahe heart.... EVERYONE at one time or another has finish problems. It is the bete noir of building.

Many finishes will do this. Differences in the expansion / contraction rates between the substrate and top coat. Flexibility of finish is a tricky balancing act. The harder a finish is the better it stands up to wear and tear, and takes and holds a shine better, while a flexible one is far more difficult to get a high gloss and generally is less abrasion resistant.

I don't know what they used as a finish, but from the look it appears to be lacquer checking. Too thick and / or thermal shock are the most common causes, with age most likely be a contributing factor.

Also, the finish will continue to perform it's purpose. I don't recall the age of white labels, but crazing is common on many older instruments, it comes with age.

I have a ninety year old instrument with no crazing whatsoever on it, so age isn't necessarily the cause. The crazing on that instrument wouldn't prevent me from buying it, as long as it sounded good and played well, but it would affect how much I would pay for it. Crazing is also an indication of how well an instrument has been taken care of and gives an indication of potential problems such as loose bracing or seam separations. Things that may not be readily seen in a photo.