Double Bass Sealing a Bass?

[Ike Harris]

Long ago, I used to go to a luthier who was fond of a technique he called "sealing" a bass. When he had an instrument he either wanted to use himself or put in a good amount of time to set up well he would do this: When it was time to glue the top on, instead of merely clamping the top after applying glue, he would painstakingly sand (or carve, I can't remember) the parts of the top table that didn't line up perfectly with the ribs(I may have that backwards, with the ribs being altered instead). So when it came time to glue the top, the top sat on the ribs without any gaps with a minimum of pressure, with something like a book on the top to set up the gluing. The purpose of all this was to have a bass that was to avoid undue tension in the top table and have an instrument that played very easily. He never used an adjustable bridge on a bass set up this way.

Has anyone else come across a procedure such as this?

 

[toman]

Makes sense to me; I would think it's probably a pretty normal thing to do on a bass that's being restored or extensively repaired. I'm no luthier though...

 

[olivier]

snip... So when it came time to glue the top, the top sat on the ribs without any gaps with a minimum of pressure, ...snips

...most of the time such a perfect match cannot be obtained... (not to mention when the ribs have to be shortened), then your luthier go for the clamps, I think.

 

[arnoldschnitzer]

You can fit a bass top or back up perfectly, with zero tension. Then it gets cloudy, the humidity or temperature changes a bit, or the planets re-align, and suddenly it doesn't fit so well. So you glue it up with a reasonable amount of pressing and cajoling. The most important two factors are that the glue joints are nice and square, and there is a minimum amount of pulling or pushing the ribs into position. Pushing the ribs in forcefully practically assures future cracking. Also, tops need to be glued in with weak glue, to allow seams to release in the future. Jeff glues them on with "spit".

 

[Nick Lloyd]

Adjustable bridges have more to do with the neck projection rising and falling with the seasons. There is also the factor of the instrument swelling and shrinking, but I still see basses with perfectly fitted tops that need adjustable bridges.