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 Post subject: glue application
PostPosted: Tue Aug 18, 2020 9:14 am 
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Koa
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First name: Richard
Last Name: Hutchings
City: Warwick
State: RI
Zip/Postal Code: 02889
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Status: Amateur
After reading the recent thread on glue bottles, I got to thinking of the mess I make using brushes to apply it. I see some utbers dabbing glue on with something. I don't think that would work with hide glue but fish or yellow it would be fine. For attaching tops and backs, I just use the glue bottle tip and run a narrow bead around the edge but it still ends up running too much. What's a good clean way of doing it?

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 Post subject: Re: glue application
PostPosted: Tue Aug 18, 2020 9:53 am 
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Brazilian Rosewood
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Joined: Sun Mar 30, 2008 8:20 am
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This will sound stupid, but use less glue and spread it with your finger tip. Keeping the inside of the box clean is more difficult than cleaning up the outside, so after I apply glue to the entire surface of the linings I push most of the glue off the inside edge to minimize squeeze out inside the box. I have used solid linings on the last several so no kerfs to leak glue onto the sides. I like to have a thinner application over the whole surface rather than a bead on the edge and hope it squeezes out over the entire surface.
I am not known for cosmetically perfect interiors, and would rather have a little squeeze out showing than a loose brace. I try not to be too sloppy, but sometimes it appears that way. pizza


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 Post subject: Re: glue application
PostPosted: Tue Aug 18, 2020 11:07 am 
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Brazilian Rosewood
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First name: Bryan
Last Name: Bear
City: St. Louis
State: Mo
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I think I'm a lot like Clay. I use less glue than most of the videos I see. Talking about titebond here. It always seems to me like people are globing on way too much glue causing tons of squeeze out. I like to spread it thin with my fingertip and make sure the surface is all wetted out with a thin layer of glue. I do this to both surfaces sometimes depending on the glue up. If I don't, I make sure there is enough glue to get the other surface sufficiently wetted. I don't have a whole lot of squeeze out when I clamp. Usually there is a small bead that forms at the edges showing me I had enough in there that some had to come out but not so much that it is drippy or messy. I tend to clamp my stuff up pretty hard.

I've never had issues with my joints but I'd be interested in feedback from those with reliable experience.

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 Post subject: Re: glue application
PostPosted: Tue Aug 18, 2020 11:46 am 
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Brazilian Rosewood
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First name: Brad
Last Name: Combs
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I had a conversation with someone a while back about those nifty dobbers that you see in the Greenfield video on YouTube. Here are some if you want to buy them. :)

https://www.amazon.com/gp/product/B01MT ... UTF8&psc=1

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These users thanked the author bcombs510 for the post: Pmaj7 (Wed Aug 19, 2020 11:05 am)
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 Post subject: Re: glue application
PostPosted: Tue Aug 18, 2020 12:14 pm 
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Contributing Member
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First name: Don
Last Name: Parker
City: Charleston
State: West Virginia
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Focused on hide glue:

You can thicken the glue a bit by using less water to make it in the first place. I find a 2 parts water, 1 part dry glue proportion (which is a standard recipe) to be way too runny for me. I tighten that up to 1.8 parts water, 1 part dry glue, or even less sometimes.

I also use masking tape in some places to keep control of where the glue goes when I spread it. For instance, if I am gluing a back brace in the go bar deck, I could spread glue on the brace and the place it, but I am more likely to mask off the areas about 1/32" outside of both sides of the brace location and just spread the glue liberally. It is mostly in the gluing area, but a little bit on the tape. Then I put the brace down into the glue. Both the back and the brace have been warmed first. This gives me plenty of time to get the placement just right (within the taped area) and the go bars sprung into place. After gelling, I lift off the tape, which takes most of the excess with it, and clean off the very small line of squeeze-out at the corner using a sharp wooden stick.

Finally, not all brushes hold glue very well. I tried the silicone brushes, but they just don't hold glue the way I want. The thin handle acid brushes seem to be my favorites these days. Natural bristle brushes seem to work better for me than nylon bristles.

I hope these things help.


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 Post subject: Re: glue application
PostPosted: Tue Aug 18, 2020 1:23 pm 
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Brazilian Rosewood
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Joined: Tue May 13, 2008 10:44 am
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Location: Virginia
It really does take far less glue then most people think, I think. At least for me anyway it took about 20 guitars before I realised I don't need to gob the stuff on. I've never used one but in videos I have seen those roll on brayer's(sp?) seem to put down a proper film.


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 Post subject: Re: glue application
PostPosted: Wed Aug 19, 2020 11:17 am 
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Location: Seattle WA
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I use a mini roller to put the glue on the perimeter for tops and backs. I can pretty much get the exact right amount. However, glue that is just the right amount and the right thickness will tend to dry quickly on thirsty wood. I pre-moisten the linings on the rim and the gluing surface on the plates with water. Then with the roller spread glue (titebond thinned with water) to both surfaces.Image

Pat

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 Post subject: Re: glue application
PostPosted: Wed Aug 19, 2020 7:55 pm 
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Brazilian Rosewood
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Joined: Fri Aug 19, 2005 4:02 am
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Location: The Woodlands, Texas
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Pat, I would be cautious about pre-wetting. I was wondering about this same thing many years ago and did some strength testing of pre-wetted and non-wetted joints using mahogany and Original Titebond. After letting the joints cure overnight I broke them apart. The pre-wetted joints came apart easily right at the joint. The non-wetted pieces broke normally in the wood and not the joint. It was a dramatic difference.



These users thanked the author Barry Daniels for the post: Pmaj7 (Thu Aug 20, 2020 12:29 am)
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 Post subject: Re: glue application
PostPosted: Thu Aug 20, 2020 12:29 am 
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Joined: Sat Jan 31, 2009 8:50 pm
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Location: Seattle WA
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Interesting. Could be the amount of water used. I just use a small piece of paper towel wetted with water. Rub it along the joining surface and the small amount of water disappears instantly. By about the third to go around it takes about 20 seconds to dry. So, pretty much putting the glue on dry wood. I believe the water I put on just slows the process down a bit.

This and the linning are the only joints where I do it. No problems after 20 instruments. I learned from my teacher who had done 85 instruments without any problems.

Pat

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 Post subject: Re: glue application
PostPosted: Thu Aug 20, 2020 5:33 am 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Sun Mar 30, 2008 8:20 am
Posts: 5968
I pre-wet or "size" end grain glue joints with glue and I just leave it open long enough for the glue to sink in, but not so long that it sets up. It is a common practice to avoid starved joints on end grain.
https://www.woodcraft.com/blog_entries/ ... -end-grain
https://blog.lostartpress.com/2019/07/0 ... s-it-work/


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