Banjo Hangout Logo
Banjo Hangout Logo

Premier Sponsors

249
Banjo Lovers Online


Want to hide these Google ads? Join the Players Union!
Sep 11, 2019 - 7:46:42 AM
200 posts since 4/2/2008

I've noticed several recently built banjos from a variety of makers, less than 10 years old, with considerable cracks in the finish. Yet, I've seen 30 - 50 year old banjos without any checking.

I am thinking the cause might be environmental, because I've also seen two banjos from the same maker of the same year - one with checking and one without.

Anyone know for sure?

Gary

Edited by - Cessna172 on 09/11/2019 07:47:22

Sep 11, 2019 - 8:39:52 AM

1637 posts since 2/10/2003

Checking in a nitrocellulose finish occurs due to the instrument being exposed to extreme temperature swings in a short amount of time. In other words, if an instrument is taken from extreme cold right into extreme heat, the finish and the wood expand/contract at different rates which causes the checking. That is why you should let an instrument acclimate inside its case so it either warms up or cools down slowly which will lessen the chance of checking. So I guess it is environmental because it is caused by temperature changes, however it is more so caused by negligent care of the instrument.

Sep 11, 2019 - 8:42:54 AM
likes this

beegee

USA

21294 posts since 7/6/2005

A lot is dependent on how the finish, especially lacquer, is applied. if too many coats are applied before the proceeding coat is cured, it can increase checking. Also, the type and manufacturer of the lacquer, the ratio of lacquer to reducer, humidity, temperature, the moisture content of the substrate(wood), the condition of the wood, filler or sealer can affect the final finish coat.

Sep 11, 2019 - 8:50:29 AM

12057 posts since 6/29/2005

It's a combination of environmental, the method of application and the kind of nitro lacquer. 

I had a long conversation with a chemist from Behlen a couple of years ago because I had a lacquer cracking problem in the winter and had to strip and refinish a neck. I needed some advice.  He told me that Behlen and several other companies make special lacquers for musical instruments called "musical instrument lacquer" (good name).

These lacquers are more flexible than furniture lacquer because musical instruments vibrate and expand and contract more than say, dining room tables.  There are a lot of luthiers out there who are much smarter than the people who make the lacquer and so they don't use the actual musical instrument lacquer (like the people who string instruments with fishing line instead of buying actual instrument strings).

The other thing is that before the first coat of lacquer sealer (which should be the vinyl kind) the instrument must be sanded to no finer than 320—the idea being that you need  microscopic little scratches in the wood to mechanically bind the first coat to the wood or it releases, no matter how many coats, which melt into one another are put on top—guess what happens when it releases.  Lois lane to Superman as he flies off with her—"You've got me, but who's got you?

The combination of sanding the neck or resonator too fine, using furniture lacquer instead of instrument lacquer, and living in a climate with changeable temperatures is a 1-2-3 punch that leads to crazing.

Sep 11, 2019 - 9:21:37 AM

Jbo1

USA

813 posts since 5/19/2007

And sometimes it is a bad batch of lacquer. Many, many years ago Mossman Guitars sold off a bunch of their guitars for really cheap because the finish that had been applied severely cracked. Rather than strip and refinish, they sold them off. If memory serves, it pretty much did in the company. Too bad, because those were really nice guitars.

Sep 11, 2019 - 9:44:02 AM

1856 posts since 4/7/2010

As a teen in the early 1970's I saw finish cracks forming in the lacquer on my parent's Martin D-28 guitar. We had a bottom of the line Dodge van with minimal insulation and no heat other than the front 2 seats. In the hour it took to drive from Cleveland to Kent, Ohio in January the guitar got exceptionally cold. Though we knew it was a bad idea to open the case, we were performing on a radio show with a schedule. The cold guitar and warm air did some quick relic'ing to our family's guitar.

There are also some lacquer formulas that are prone to finish cracks. I remember Mohawk lacquer of the 1970's and 1980's was susceptible to finish cracks, even without a 1972 Dodge van in January.

I also remember Sherwin Williams was involved in a lawsuit with Stelling and other instrument manufacturers in the early 1980's because of an unannounced change in their lacquer formula that necessitated refinishing many instruments by some instrument makers. But I don't remember exactly what the defect was. I'm sure someone will chime in.

Bob Smakula

Sep 11, 2019 - 10:46:50 AM

Jbo1

USA

813 posts since 5/19/2007

Bob Smakula , I believe that was the incident that Mossman Guitars was involved in.

Sep 11, 2019 - 11:52:58 AM
likes this

6040 posts since 8/28/2013

quote:
Originally posted by Ken LeVan

It's a combination of environmental, the method of application and the kind of nitro lacquer. 

I had a long conversation with a chemist from Behlen a couple of years ago because I had a lacquer cracking problem in the winter and had to strip and refinish a neck. I needed some advice.  He told me that Behlen and several other companies make special lacquers for musical instruments called "musical instrument lacquer" (good name).

These lacquers are more flexible than furniture lacquer because musical instruments vibrate and expand and contract more than say, dining room tables.  There are a lot of luthiers out there who are much smarter than the people who make the lacquer and so they don't use the actual musical instrument lacquer (like the people who string instruments with fishing line instead of buying actual instrument strings).

The other thing is that before the first coat of lacquer sealer (which should be the vinyl kind) the instrument must be sanded to no finer than 320—the idea being that you need  microscopic little scratches in the wood to mechanically bind the first coat to the wood or it releases, no matter how many coats, which melt into one another are put on top—guess what happens when it releases.  Lois lane to Superman as he flies off with her—"You've got me, but who's got you?

The combination of sanding the neck or resonator too fine, using furniture lacquer instead of instrument lacquer, and living in a climate with changeable temperatures is a 1-2-3 punch that leads to crazing.


Ken, I can really appreciate your sarcastic comments about luthiers being more intelligent than the people making the lacquers.  I ran into the intelligence factor many time while repairing/tuning pianos. too many clients had read some low quality book on the subject of pianos, and seemed to think that me, with some 30 years of hands-on experience and with an understanding of the actual physics, glues,  and repair techniques involved, would tell me what I should do and how to do it.

I've seen that superior knowledge in many other fields, too. My own older sister is more intelligent than her pool man, because she has experience as a chemist, whereas the pool man only knows swimming pools. (My sister is almost always more intelligent than anyone else.)

This intelligence is the prime reason for those signs in mechanics' shops that read $20 hr. labor, $100 if you help.

One company I worked for had an issue with an adhesive. I was the only person there that actually called the manufacturer to get proper advice. Everybody else was too smart to think of doing that.

Hangout Network Help

View All Topics  |  View Categories

0.171875