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I searched the forums but couldn't find the answer to this one so I need some expert advise please. I have a bridge that's just starting to lift. The separation on the back of the bridge is very small right now, maybe 1/10 mm but it runs a good inch at the back of the bridge.

Would it be best to remove the bridge and re-glue it completely, or work some glue into the lifting area and clamp it? I can't get it to close when pushing down on the back of the bridge.

It doesn't matter to me which one I end up doing, but if working some glue under the lifting area will hold for a long time (ie, not cause other problems or be just a temporary fix) then that's what I'll do.
Thanks for any advice!

It is very common to have to remove a bridge and reglue it. A heating pad on top, work a pallet knife under it. Clean all the old glue off and make sure there is no finish left in the foot print - unfortunately a lot of guitars don't have all the finish removed. Make a good clamping caul for the inside and figure out how to keep it from getting glued to the bridge plate (glue will come thru pin holes). I make my cauls out of UHMW, you can probably put waxed paper over it. Two or three or four deep clamps, be sure to get the wings and either AR or HHG depending on the guitar and your ability to work with it.

Trying to work glue into the crack rarely works - first, new glue usually doesn't stick to old unless its hide, second if you use anything other than good wood working glue it is hard to get off in the future when you decide to do it right.

Sometimes you will have damage to the top, splinters that pull up with the bridge. You just have to work with whatever you've got - sometimes you can glue them back in. Drill out the pin holes and ream, they will get filled with glue.

I've got lots of pictures if you need more help but its pretty straightforward (and unfortunately, pretty common)

How long has the crack been there? It is getting towards the dry part of the year, you know. Have you tried keeping the guitar properly humidified?

_________________
"Act your age, not your shoe size" - Prince

Thanks for your quick replies!
This is one of the guitars I built several years ago. I like to build, but I hate to repair so I don't know these types of things. Of the 16 I've built, this is the second one that had the bridge lift. The first happened fast (from no lift, to lifting... about a day). It was big enough to drive a truck under. Way too much to just squeeze more glue in. I took it off, prep'd everything, and reglued it. No problem since.
Chris - I think its been about a week since I looked at it before noticing it today. I charge my humidifiers every week and that's also when I check the bridge for lifting (since I had that other one happen, a must for me).
Freeman - I have everything I need to R&R the bridge, but thanks for input since I may not have known. When you said "Trying to work glue into the crack rarely works." That's exactly what I needed to know!! I won't bother with that then. I'll just R&R the bridge.
Both of these lifts are probably due to some dumb rookie thing I did when I built them. I admit that I used to leave about 1mm of Shellac inside the footprint of the bridge so everything would look "perfect". I thinned that area down carefully as best I could with a razor blade but you can never scrape off all the finish to bare wood with a razor blade. That's possibly the reason. Starting about 3 guitars ago, I still finish inside the footprint to about 3 mm, put the bridge down with just the two bridge pins, scribe around the bridge with an X-Acto knife, and then actually get that all off nicely with a chisel. That takes it to bare wood. So far so good....
Thanks for both your help!! R&R it is....
Joe
PS - I'll be using Fish Glue, which is what I now use to put on new bridges. I think the old glue was Liquid Titebond Hide Glue. I won't be using that anymore on ANYTHING since I also had one side of one of my X braces come loose too for no good reason!!!!!!

Everything I have heard about liquid hide glue says stay away...

As with ALL glues - make sure it's fresh. I learned decades ago to toss it away when it's one year old. I buy all new glues around the beginning of the year, and put tape on them with the date of purchase. I don't care if 75% of the glue is still in the bottle... Give it the heave-ho.

_________________
"Act your age, not your shoe size" - Prince

I agree on both counts. Thanks again for your help!

Yup I mark the date on glue bottles too. When they retire they become household glue or stuff for building forms and that sort of thing. Or it gets tossed. I built my second guitar with Franklin LHG and that was almost 30 years ago and it is STILL holding together. In fact I was playing it last night. It's a classical guitar so it's under less stress but in the end I got lucky. If your bottle of LHG is not very fresh then it's not worth using.

FWIW fish glue is prone to coming loose with high humidity problems too.

The fix for a lifting bridge is to remove it, clean it up and reglue it. If it was hot hide glue then you could get away with regluing it in place but in this case it's probably best to start over. I would recommend you use Titebond. Or what I have been doing in the last year is making my own LHG. By adding salt or urea in the right combinations you can extend the open working time of HHG. I put it in small glue bottles with a few stainless steel bolts at the bottom for weight. It's not liquid at room temperature so I put the bottle in my glue pot at 140deg F. When I'm done for the day the bottle goes in the refrigerator.