Official Luthiers Forum!

So here's what the boys used to call the 'rack and stack' on bridge glue-ups for small shops:

- Perfect joint on new production: pretty much anything will work, as the glue line can be easily closed, but usually fresh AR/PVA or HHG (192g minimum) and reasonable clamping in a commercial shop setting.

- Re-glue on bridge patch in reasonable shape which can tolerate fairly aggressive prep (e.g., the usually AR/PVA-contaminated 1970's Martin): AR/PVA with higher clamping pressure at glue line or 315g HHG with reasonable clamping across the bridge patch.

- Re-glue on vintage instrument with bridge patch issues: 315g HHG with good clamping across bridge patch

- Cheap plywood-top guitar with bridge joint failure and delamination/extensive damage to the bridge patch; West 105/205 epoxy or equivalent

In other words, pick the glue that matches up with joint quality and ability to effectively clamp.

I did not say "...don't use Titebond" despite my general loathing of the stuff for use on an instrument. I did suggest that there is a decent correlation between condition of the joint and success using ANY glue, but especially Titebond. Having done lots of bridge re-glues at Greenridge over the time I was there, and seeing what did NOT worked coming in the door for repair, I developed a reasonable understanding of what will not result in call-backs. In general, our bridge repair work was done with 315g or - in a very limited number of cases - overnight cure epoxy.

Again - pretty much any suitable glue will work on a near-perfect joint with effective clamping. Not the case on a 1934 000-18 with significant prior damage to the patch, but how many of those or similar will you have in the door this year? Is this scenario the usual bridge re-glue use case for the average OLFer? I hope not.

For that more general case, IF you can close the glue line to < 1 mil, it does not really matter what glue is used, as even a thermoplastic adhesive is unlikely to display noticeable cold creep with a very thin glue-line, and that same thin glue-line will be more resistant to hot creep given exposure to owner carelessness.

If you can do 315g, the combination of zero hot or cold creep, reversibility without significant clean-up, insane strength in applied loading after minimal drying time, and tolerance for truly horrendous combinations of bridge patch condition after allowable prep and clamping pressure make the stuff the lowest risk option for a commercial repair operation. If not in that particular situation, just shoot for a good joint and clamping such that you get that thinner glue line. Things will likely work out just fine.

_________________
For the times they are a changin'

- Bob Dylan

Woodie, is there a specific benefit for loading the bridge after a few hours cure when using the 315 hhg?

I usually let every joint sit overnight before removing clamps, even though I read from Franklin’s website that you will get a stronger joint when using Original Titebond if you remove the clamps after a couple of hours and let the joint reach full 24-hour cure in a relaxed state, before applying a load.

Besides the issue of having to leave a guitar under clamps and unmolested for 24 hours of cure (Titebond) or drying (HHG), it allowed me (a not quite weekend warrior... 3.5 days per week at most) to glue up a bridge in the AM by 8 AM, unclamp after lunch, then refret and nut/saddle to string up by 3 or 4. It left less on the bench for others to do, so there is certainly benefit in the right shop.

We did push that for a bridge reglue that was walked in at 10 AM for a 4:40 sound check at Strathmore... not something to try with other glues or without complete familiarity with 315g. IIRC, that was an Olsen that was glued up with TB that showed a lot of evidence of cold creep in the finish in front of the bridge as well as the separation the player noticed.

_________________
For the times they are a changin'

- Bob Dylan