Open Glue Discussion

[tippie53]

It seems the glue thread is a hot topic.
I would love if we can determine some good testing of glues that can make sense in a comparative study. Yes tite bond is a good glue , but there are more the gram strength.
Most studies are from a structural engineer point of view , I would like to see a more guitar related study. I guess what I am asking , is what criteria of testing would make sense ?
1 strength
2 open time
3 clean up
4 tonal inference
5 creep
6 ease of removal.
So what can we add to this and what can we do to make this as scientific as possible ?

I pose this

we need to make some defined specs on the joint size , clamping procedure and clamp time
next we need to allow a cure period
the stress test must be specific as is the joint construction
tonal test and dampening effect need to be done to an exact procedure and if anyone here has access to a good spectrum analyser and signal generator that would be good.
Amount of glue used
and anything I missed.
what say guys are we up to this?
let me know as this would be a good way to collect viable data.

[tippie53]

with a spectrum analyzer , no as it takes the subjective data out of the equation. Penn state University and Martin are doing some work. The acoustic lab seems to see a difference in some woods for tonal inference
If it is at a level where a human ear can tell a difference , I don't know but I think I can hear a difference. My opinion only .

[B. Howard]

with a spectrum analyzer , no as it takes the subjective data out of the equation. Penn state University and Martin are doing some work. The acoustic lab seems to see a difference in some woods for tonal inference
If it is at a level where a human ear can tell a difference , I don't know but I think I can hear a difference. My opinion only .

I would hazard a guess that Martins analysis is geared more toward finding suitable replacement materials with similar resonant qualities to traditional materials, hopefully to improve those awful formica guitars. It is one thing, where one has a set of parameters they want to match to use a spectrum analysis to make comparisons. But in the case of a proposed study of adhesives and their effect on tone, what is that standard to which comparison will be drawn? Should the adhesive have perfect vibrational transmission, or is some damping in the system beneficial? And do different joints have different needs in these regards? What about when different wood combinations are employed, will the adhesive need to change as well to meet the standard? Testing may well be the easy part, it's finding the standard to compare to that will be hard.

I had an interesting thing happen here the other week. An HD-28 was in for some finish repair, came in unstrung. Playing comfort aside, I am not a big D model fan. I find them to be overall a bit boomy and even percussive at times. I use a pickup clip with my bench tuner, clipped on the headstock to tune up. My pickup would not read off the headstock of this guitar, at first I thought the pickup went bad but not the case. I had to clip it on at the edge of the soundhole to be able to tune it, which I figured meant there was going to be some type of structural issue I had missed. But once up to pitch I was amazed to hear a clear mellow and even tone. Easily one of the best sounding dreads I have heard. Definitely not what I expected. So in this case at least it would appear that whatever damping was occurring was beneficial, at least to my ear. And the key there is "to my ear", you may not have liked the tone of that instrument because it did not sound like most other dreads. So was that guitars tone good or bad? or just different?

But to answer the original question, yes, count me in. We just need to develop a standard to compare too.

[tippie53]

actually The study is about GLUE and the tonal inferences. The initial study shows that the wavelength amplitude is stronger with less degradation using hot hide glue over tite bond. In order for the study to be valid and the results to a true conclusion , they need to have more samples.
This has been on going for a while but I have not seen or heard any results in the last year.

[B. Howard]

I could buy into that to an extent. I can hear a difference in a french polish finish, but do not know if it has more to do with being a natural protein or less coating weight or a stiffness thing. I would propose a test scenario perhaps similar to the one Roger Siminoff did on lacquer a few years back with perhaps a few changes in actual testing procedures. Do you know the study I mean? If not I'll get a copy to you.

[B. Howard]

My initial response to this post had to be taken down but I feel the information none the less very useful. It is a link to a test done on most types of wood glue. It is very scientific and takes into account species and fit up.

http://www.oldbrownglue.com/pdf/HowStro ... ue_FWW.pdf

If you wish to share this information with others, please make sure and share the web link and not the pdf that your browser may automatically download. That was the problem with my post. I then quizzed John if by including the topic of tone in the study if we were not embarking on a chocolate or vanilla type of a thing. John responds with the spectrum analyzer.post.

[tippie53]

There is much to learn from the discussion . You are on the right track in that the glue creates a bond between 2 pieces of wood. The thickness of that material and the harness can influence the dampening effect of this joint. How can we test this to see if the effect is real or fantasy.
Many opinions on this subject for sure and I hope we can find a resolution . If we can joint resources and see what the end results are . we may as a group learn something.

Also on a side note , There was a point made to me about legalities of posting copyrighted material. Unless you have permission of the author , we need to post links to that information. Information from a government , ASE ,or the Manufactures web page are ok but private studies we need to keep to a link for legality issue.

In order to make this test viable , it will take a commitment and I hope I can get some help. Any Engineers out there that may be able to point us to proper date gathering techniques your help will be appreciated

[rienk]

I posted some thoughts on this discussion on the other thread (wasn't sure where to put it).

Does anyone have much experience with Liquid Hide glue - which did well on this study?
Would anyone be willing to briefly explain the differences between HHG and Liquid Hide glue?
Thanks!

[tippie53]

The cold hide glue is ok but has a short shelf life. Most use the Hot Hide glue.
I do not use it personally

[B. Howard]

I posted some thoughts on this discussion on the other thread (wasn't sure where to put it).

Does anyone have much experience with Liquid Hide glue - which did well on this study?
Would anyone be willing to briefly explain the differences between HHG and Liquid Hide glue?
Thanks!

My understanding is the liquid stuff has food preservatives in it it to help the shelf life, and something similar to keep in in liquid. I have used more of it over the years than HHG. I have done some testing of my own and see no functional difference as far as actual holding power versus HHG. It steams apart about the same as well. But I caution that most of this experience has not been guitar related. I will be interested to see if it has the similar sonic conductance to HHG. It's also easy to test if it is stale, put a thin smear on a piece of paper and if it hasn't dried in about 20 minutes it is no good. That same test by the way can be used for shellac and I would imagine any other protein based substance we use.