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I didn't get as far along with my build this winter as I had hoped. I got the box built and the neck fairly close to final fitting. As spring slowly approaches here in eastern Canada though I am wondering if it is too late to glue my bridge on. My honeywell30 buck gauge says 41% but I don't have complete confidence in it. It's jus rainy a lot now & it feels damper. At what humidity do you think it's too high to glue a bridge on.

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Mike McNerney

Theoretically I would think that the closer you are to what the relative humidity was when you closed the box the better.

That’s where the top should be happiest and move the least.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Sounds like you need to calibrate your gauge.

I don't have a climate controlled shop so I do pay attention to humidity, for things like shaping and gluing braces, closing the box, attaching the fingerboard and applying finish, but.. I have never worried about RF when gluing a bridge. The only thing I do is dry fit it. As long as it still fits nicely, and hasn't curled up on me, I glue it. I have never noticed a problem.

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Joe Beaver
Maker of Sawdust

I agree with Joe, I have never overly concerned myself about when I glue it on. Living in the pacific northwest where rain is a way of life,we often have months where it rains everyday, there is not a great relationship between rain and relative humidity. Sure evaporation of the rain might raise it a bit. We rarely go over 50% RH.

In a cup put a half a cup of salt in a 1/4 cup of water. The salt will not totally dissolve. Seal that and your gauge in a seal-able plastic bag. Wait eight hours and see how close your gauge is to 75%.

I suspect that you are well in the range to glue on a bridge. Spring is probably the best time of year out east. It is not so cold that heated air is super dry also the summer humidity has not started.

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http://www.Harvestmoonguitars.com

Potassium carbonate is a better salt to use to calibrate a hygrometer for our purposes, because it creates a relative humidity in the range we want (around 43%).

What Don said. ^^^

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

thanks all

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Mike McNerney

Fwiw, at the largish factory that was my last job, all guitars were put in the climate room before bridge fit...

Do you remember what the RH was kept at in that room & for how long. My guess is that thin soft wood (spruce) would stabilize in a few days??

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Mike McNerney

42%, from an environment that was not too far off from that most of the time. At least 24hrs, often longer...