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Are there any precautions I ought to honor before gluing on a rosewood bridge (I never have taken any, but it's never too late to learn to do it right)?

I think it's good practice to scrape the bridge immediately before gluing, and scrape, not sand, the gluing surface of the soundboard as close to gluing as practical. Anything else?

Thanks!.

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Peter Havriluk

Good fit, fresh surfaces, fresh glue, good clamping and your good to go.

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Jim Watts
http://jameswattsguitars.com

Good job Peter scraping is important.

What are you doing to be sure the bridge is exactly where you want it? Some people use pins. We create a pocket with a rabbit on the bridge perimeter.

You don't need to have any guide but be ready to be able to wipe away squeeze-out so you can see if it's located where you want it.

I would suggest though that you do a dry run using all the clamps you intend to use and then apply pressure to the clamps. While the clamps and bridge are in place use masking tape to create a "stall" like a horse stall on three sides. I use two layers of masking tape in front of the bridge and on the sides. I have the tape butted right up against the clamped bridge.

This creates a "well" of sorts on three sides for the bridge to fit into and not shimmy around on slippery, wet glue. It also verifies that the bridge is where you want it and takes the drama out of what happens if it's slightly off and out of place.

Just be sure when you slap the bridge down into the well that it's not sitting on top of any tape and instead within the horse stall that you made out of tape. After all clamps are set and snugged remove the tape which will go a long way toward glue clean up too. Never leave masking tape on a guitar finish very long it can eat into some finishes.

Now you have it in place and located properly. You also just went a long way in your journey to learning to use HHG for bridges too since you now have a method to quick locate the bridge without having to rabbit the bridge bottom and create a pocket. There is a method to what I share with folks here by the way.

Hope this helps and good luck this should be drama free and productive.

"I think it's good practice to scrape the bridge immediately before gluing, and scrape, not sand, the gluing surface of the soundboard as close to gluing as practical."

That's what I do; so far so good.

I've always worried that using solvents to clean the rosewood surface of oils would simply pull more oil out and leave a film. Maybe one of these days I'll make time to do the experiment...

Hi Alan,
While you are experimenting with oil removal, try one with concentrated dish detergent followed by thorough rinsing and drying. It seems to remove oils better than solvents.

" (Detergent) seems to remove oils better than solvents."

Perhaps, but since I have not had any problems in more than 40 years with the process I'm using, I see no reason to change.

The why of the thing is often as important to understand as the how or the when, and the why piece of surface preparation has to do with creating a pair of joint surfaces that are optimized for greatest bond strength. Removing surface contaminants such as oxidized resins and extractives, as well as creating additional bonding sites within the cellulose/lignin composite is the reason why we plane, scrape, or sand wood as a final joint preparation step.

Trying to chemically accomplish the task may work against us by simply redistributing those contaminants while also failing to increase surface energy, which is ultimately the goal of pre-glue up joint prep. Keep in mind that, depending on the species, rosewoods may require both polar and non-polar solvents to dissolve the superficial resins and extractives present, so an acetone or naphtha bath and a some scrubbing with water and a detergent just tends to create another wetting/drying with most of that undone by that final, FINAL plane, scrape, or sand cycle. This process can go on for some time if the objective of the exercise is not kept in mind - removal, rather than redistribution - of contaminants and increasing the joint's overall surface energy.

I have wild cat mamas that bring their kittens to sun on my deck on cool days. While it looks like great fun for the little ones to chase their tails, I try to avoid doing the same in the shop. Plane, scrape, or sand to get two well-fitted, fresh surfaces and give the adhesive the best chance possible of keeping things together.

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For the times they are a changin'

- Bob Dylan

All's well that ends well. Mr Goldberg and I got it attached in the right place and it looks like somebody tried real hard to be neat about it. Onward!

Thanks folks. This was a full semester of bridge considerations.

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Peter Havriluk