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Author Topic: holding wood together while glue sets  (Read 1692 times)

roycv

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holding wood together while glue sets
« on: May 17, 2017, 11:22:02 AM »

Hi all, envious as I am of the superb building skills of many of our members I notice that photos during construction have spring clamps and many of them.
You will get a far superior joint with a screw or lever type clamp.

This was brought home to me some years ago when I found I had made a mistake in the early construction of a hull and I had to remove a 30 inch length of wood and turn it over.  This had been held in place along its length by a series of clamps until dry.
Anyway the glue was dry and the outer parts came away fairly easilly by inserting a knife blade along the joint.
As there was more room in the middle section I had used screw clamps.  The joint there was permanent and I ended up just cutting the wood away and sanding down.  Had to make another piece up to fit.

Now I still use spring clamps and they are cheap but I just buy screw or lever pressure clamps now.
Perhaps do your own experiment and see for yourself. 
I cannot say that it is twice or more as strong, it is just one comes apart and the other does not.
Best regards Roy

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nemesis

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Re: holding wood together while glue sets
« Reply #1 on: May 17, 2017, 12:28:10 PM »

do not know the glue you were using but I have no trouble with epoxy or polyester. nemesis
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grendel

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Re: holding wood together while glue sets
« Reply #2 on: May 17, 2017, 12:50:40 PM »

for spring clamps I use those bulldog clip type, plenty strong, but most of my work is done using old fashioned G clamps, I have about 40 1" ones, and even some deep reach ones for certain uses.
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roycv

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Re: holding wood together while glue sets
« Reply #3 on: May 17, 2017, 02:23:07 PM »

Hi,if my memory serves I was using an aliphatic resin glue,  I do not tend to use epoxy on wood. My point is best illustrated with a small test piece.
I find a strong PVA glue very good on wood.  I buy some that comes in a tin I think from B & Q.
I figure that if the glue joint is as strong as the wood that is enough, sanding could be an issue.
regards Roy
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tigertiger

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Re: holding wood together while glue sets
« Reply #4 on: May 17, 2017, 03:17:37 PM »

I do other woodwork, and never buy less than a quart of PVA at a time, it is really cheap that way. It lasts for years, providing you keep it in a closed bottle or tub. I just fill up old glue bottles from the tub. I have used Gorrila glue, but to be honest, it is probably overkill, as a PVA glue joint (on the long grain) is stronger than the original wood (as mentioned above). On end grain, I will reinforce with splines or biscuits.
Clamping does not need a lot of pressure, but screw clamps would help the glue get into the fibers. The other important thing is a smooth finish on both pieces. I guess if the surfaces are rough then Gorilla glue will come into its own as the slight foaming would reach into all of the crevices.
The grab time for PVA is 5 mins, and it goes off in 30 mins, fully dry in 24 hours. One good thing about PVA is that it is water soluble. You can wipe off excess with a wet rag, and you can extend grab time by 5 mins if you add 5% water.


Sorry if I am teaching anyone how to suck eggs.
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Onetenor

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Re: holding wood together while glue sets
« Reply #5 on: May 23, 2017, 01:23:30 AM »

If you buy the right PVA it is only water soluble until cured. Once cured it is waterproof if it is the right type
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RAAArtyGunner

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Re: holding wood together while glue sets
« Reply #6 on: May 23, 2017, 02:00:37 AM »

If you buy the right PVA it is only water soluble until cured. Once cured it is waterproof if it is the right type

Do you mean water resistant a big difference.

To test if waterproof, fully immerse the joint, test piece, in a container of water for at least 48 hours.

PVA slowly dissolves when fully immersed in water.
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derekwarner

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Re: holding wood together while glue sets
« Reply #7 on: May 23, 2017, 03:19:11 AM »

 :o....yes the Americans have different marketing laws to the UK & OZ

Mr Titebond advertises his MK III version of PVA as waterproof........but if you read the test criteria it is somewhat vague  >>:-(

Derek
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tigertiger

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Re: holding wood together while glue sets
« Reply #8 on: May 23, 2017, 07:06:23 AM »

I think that for most uses, the bare joints are not immersed in water for long periods of time.
A lot of PVA construction glues are labelled waterproof.
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bj

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Re: holding wood together while glue sets
« Reply #9 on: May 23, 2017, 07:54:16 AM »

PVA Wood adhesive are labelled  from D1 to D4 grades, see below
There are 4 main types of durability grading, running from D1 to D4. The differences between these are listed below:
D1 = Interior areas, where the temperature only occasionally exceeds 50C for a short time and the moisture content of the wood is 15% maximum
D2 = Interior areas, with occasional short term exposure to running or condensed water and/or to occasional high humidity, provided the moisture content of the wood does not exceed 18%
D3 = Interior areas, with frequent short-term exposure to running or condensed water and/or heavy exposure to high humidity. Exterior areas not exposed to weather
D4 = Interior areas with frequent long-term exposure to running or condensed water. Exterior areas exposed to weather
See https://www.constructionchemicals.co.uk/blog/2015/07/13/what-are-d1-d2-d3-d4-adhesives/
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roycv

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Re: holding wood together while glue sets
« Reply #10 on: May 23, 2017, 08:24:20 AM »

Hi bj, thanks for the reference to classification details.  I looked on the 3 current containers that I have and the web site.  None of the containers I have a 'D' classification. The dearest lot was in a UniBond super strength tin and it said it conformed to minimum BBA standards.  Would that be D4?

But this is instructive as it was the glue I noted in my first post, that when 'G' or screw clamped, as against spring clamps, the joint is more than adequate for the task.

Just to clarify,  this thread was not intended to be about the kind of adhesive to use but the difference in adhesion when holding the joint together when drying.
best regards and happy glueing,
Roy
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bj

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Re: holding wood together while glue sets
« Reply #11 on: May 23, 2017, 04:58:25 PM »

D4 is the trade name of an adhesive made by EVERBUILD and seems readily available from the small (my local hardware shop) to suppliers such as TOOLSTATION.
It is less that 6 for a litre ....... As to Unibond I have no idea of their standard.
Sorry for going off at a tangent from the original post
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RAAArtyGunner

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Re: holding wood together while glue sets
« Reply #12 on: May 24, 2017, 02:11:16 AM »

BJ,

Still relevant and informative especially from the other side of the world.

Except for contact cement, am unaware of any wood glue that will result in a very good joint unless adequately clamped.

As the original post said that does not mean friction/spring clamps but a screw type of clamp of some type, such as, F clamps, G clamps, etc etc.
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