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The RH in my house dipped in this freeze snap quickly to about 35% from 45-ish.

Here's a build of mine about a year old: The bridge just popped up and the top crack is from bridge to tail block.

I feel this crack is was probably due to the humidity drop, sure but this glue joint was flawed. The glue line was more visible than my normal work and I let had it go. Well, 1 year later, this is what happened.

I know how to humidify to close and glue crack and reset the bridge.

But, I'm considering drastic measures such as replacing the top. I had hoped to sell it as new. I don't think I want to sell it even if repaired it's just going to be a long repaired crack which I think will prob open again. I think this joint is gonna be an issue going forward. Any thoughts on that?

you are correct humidity caused the crack and if you notice the grain that is torn along the glue joint shows you had a good glue joint.
I run my humidifier set to 40% when its real dry getting 50% is very hard and anything about 37% is safe

Thanks. I haven’t been measuring this room. Perhaps it crashed. Addressing. Thanks.

I noticed that also, the glue joint looks to have held.
How about fix it and keep it and make the next one to sell?
Merry Christmas too!

That settles it, Kevin. Keepin it. Merry Christmas me. I've posted this one here, it's the Rosewood OM slot head I made. It's the only build out of 23 now that I've made without knowing who it was for. I guess I know now.

I've hung it with a bag with a sponge in a plastic container w/ holes. We'll see how well I can get it to close up. Also cranked up the humidifier. I hadn't realized how much we crashed here.

Happy Holidays to everyone.

Probably 20 years ago I sent a 000 size guitar from here in Hawaii to a player in New York in the Winter. It took only a few days for the top to develop a couple of cracks from the bridge to the tail and the top to sink so much as to make the guitar unplayable. When I got the guitar back, you could drop dimes through the cracks! It was a real learning experience. Anyway, I took the guitar back. Within a few days of just sitting in higher humidity, the cracks completely closed up. I played that guitar for many years without having to do any repairs on the cracks. Along the way the guitar suffered further damages, so I no longer have it, but it was an interesting experience. Happy Holidays!-Bob

the big thing is to know what the RH is. Many hygrometers are inaccurate . You need to look on you tube for ways to calibrate your Hygrometers DO NOT ASSUME THEY ARE CORRECT.

The biggest piece of misinformation is maintaining 50% humidity. To be honest
if you can hold 37% to 42% in winter you win . I just had a customer that over humidified a guitar because his Hygrometer said it was 15%. He is in NY city. Most high rises have ventilation and maintain RH. The have City steam so its easier to heat and control RH>
I told him to get a certified Hygrometer
https://www.amazon.com/Cigar-Oasis-Hygr ... C93&sr=8-2
then use this system
https://www.youtube.com/results?search_ ... hygrometer

good and timely info. I notice the cracks have closed to near invisible after a few days w/ some humification. I still see the thin line in the shellac. Since they are mine and not vintage so I may push some glue into the cracks, then lightly sand w/ 1000 or 1500g down the line and then refresh the shellac. I think the center seam on this guitar will just be more visible than most but certainly not a big deal.