Violin Forum/Message Board

kubasa · Member Joined: 13 Sep 2007 Posts: 212

So I was gluing my spruce top together and everything went really well. The plates grabbed tightly after rubbing back and forth. I had a slight amount of glue squeeze out. All seemed good until I was cleaning up and realized that I had only applied glue to one side of the billet. Not sure what I was thinking....

(now I'm thinking out-loud....) It's drying right now and I think I'll probably just have to wait and test it out tomorrow. Part of me is saying it will be fine but part of me is quite annoyed. Again, not sure what I was thinking. I'm not worried if I have to take things apart. I've had to do that before so it's no big deal.

Anyone ever done something (stupid) like this before?

Michael Darnton · Posted: Sat Jan 05, 2013 1:15 am Post subject:

Well, there's only glue on the stamp, not the envelope, but the stamp still sticks. I don't think I'd be too worried. There was enough to squeeze out and run down the sides, right? So the other side most likely got its fair share.
_________________
new blog at my site! http://darntonviolins.com/blog
my work sites: http://darntonviolins.com and http://darntonhersh.com

kubasa · Member Joined: 13 Sep 2007 Posts: 212

That's a very good analogy. Yes, I had glue squeeze out all along the joint and run down the sides in a few places. I do think I'm okay like you say but I still can't believe I did that. I suppose there are plenty worse things to forget and have to deal with after words!

Thanks - James

Michael Darnton · Posted: Sat Jan 05, 2013 11:35 am Post subject:

If it didn't work and opens up at some point in the future, you just glue it again. Maybe that will never happen.
_________________
new blog at my site! http://darntonviolins.com/blog
my work sites: http://darntonviolins.com and http://darntonhersh.com

Janito · Member Joined: 08 Oct 2007 Posts: 114 Location: USA

When you start carving the plate take some deliberate cuts across the join at various points.

You can then test the integrity of the join by examining the wood chip that has the glue line.

Because it is relatively easy at this stage, if in doubt about integrity of the join, I would cut the plate along the glue line, replane and reglue.

violinarius · Member Joined: 14 Dec 2007 Posts: 171

I watched an expert, who made his living developing adhesives for the industry, give a lecture and this question came up.
=========================
Q: Should I glue 1 side or 2 sides?

A: If you are going to be a while before clamping, then both sides, and if you are going to be clamping quickly, then just one side is enough.
================================================================
For a quick answer you can skip to the last line.

The reason given is that all you need the glue to do is 'wet' the other surface. A glue that is exposed to the air for a while will tend to loose it's ability to 'wet' the other surface effectively.
In the case of hot hide glue, the enemy is gelling, but doing a quick rub joint, will wet both surfaces, and distribute the glue evenly.

Another problem is a 'starved' joint which is due to not enough glue to wet all of the surfaces, or too much clamping pressure that drives most of the glue out of the joint.

'Squeeze out' from applying clamping pressure shows that there was more than enough glue to do the job applied, and leads to 'peace of mind' that the joint was not 'starved', but too much sqeeze out from excessive clamping pressure can be a problem. This is where 'rub joints' come into play, with the rubbing wetting both surfaces well, and the excess glue running down the sides of the plate, and no need for clamping, therefore no starvation from over clamping pressure.
Note that with the rubbed joint you can not 'spring' the joint with no clamps, since clamping pressure brings both surfaces into mateing contact.

A 'hungry' joint is one that has too much adhesive sink into a porous substrate, leaving not enough glue in the joint.

Now hide glue is unique in that it has no glueline, or very very little, so for a successful joint, you need wood to wood contact, with either no pressure, or if you 'spring' the joint, then you need wood to wood contact with clamp pressure that is not excessive so it will not squeeze/starve all the glue out.

This unique property of hide glue, which is that it does not need to form a glueline, and as such, it is a very poor gap filler, means a very little glue goes a long long ways.

I said all that because gluing failures can have many different sources, and more that one possible explanation, so that is something to keep in mind.

If this joint fails, it should not be because only one surface was glued, but it could be because other criteria were not met.
============================================
So IF all other things being right, the joint should be just fine.

Janito · Member Joined: 08 Oct 2007 Posts: 114 Location: USA

It would take me ~15min to saw, replane and reglue a questionable spruce join.

Michael Darnton · Posted: Sat Jan 05, 2013 7:37 pm Post subject:

Are you sure it's worse than what he'd do the second time? :-)
_________________
new blog at my site! http://darntonviolins.com/blog
my work sites: http://darntonviolins.com and http://darntonhersh.com

Janito · Member Joined: 08 Oct 2007 Posts: 114 Location: USA

Michael Darnton · Posted: Sat Jan 05, 2013 9:50 pm Post subject:

Me, I cut it twice, and it's still too short. . . .

At a shop I worked in, one guy would take his apprentices' glued plates, lay them on the floor, roof-peak down, place one foot on each side (not too far out, or you break the wood, regardless), and lightly jump. If the plate stayed glued, it passed.

I later learned that it really depends how you do it. You can break any joint (glue is NOT stronger than wood, regardless of what they say) if you want to crush the spirit of the person who did the joint. The "maestro" was a class-A passive aggressive.
_________________
new blog at my site! http://darntonviolins.com/blog
my work sites: http://darntonviolins.com and http://darntonhersh.com

kubasa · Member Joined: 13 Sep 2007 Posts: 212

I was out ice fishing today and finally got back to testing the joint. The joint seems very secure to me. Before I glued, both surfaces were warmed and completely touching with no light showing through or gaps so for now I'm not going to pull it open and redo. Just like you mention violinarius, I literally had the glue on and did the rub joint in probably less than 10 seconds.

It was one of those moments that you think to yourself - "did I really do that?" but it appears that all is well! As I start carving, I'm going to do exactly what you said Janito and double check things. Thanks everyone.

As for ice fishing, my son and I caught 16 fish. My son caught 11 and I caught 5 so he out-fished me. I must be getting older because I had more fun watching my son catch his fish than I had catching my own fish!

violinarius · Member Joined: 14 Dec 2007 Posts: 171

violinarius · Member Joined: 14 Dec 2007 Posts: 171

violinarius · Member Joined: 14 Dec 2007 Posts: 171

I found a picture while over at Maestronet of the BACK plate being tested.

Photo by PeSt at Maestronet.com

Would not try this with a front plate ..... or dirty socks! Shocked