donrobinson

A small "Mythbusters" on glue

There have been many discussions and opinions about glues...which one to use... when to use it or not.... which is the strongest..... Many newcomers often ask these questions and I know myself I was told to use one type and have used it ever since. So for my curiosity I thought I would put some of these glues, the ones I have, to test and thought I would share the results with you.

 

 My little test consists of testing CA, Weldbond and Titebond. I applied these to bare walnut strips then to walnut strips that had three coats of wipe on poly. The laminated strips were clamped and left for ten days before I tried to separate them, to separate them I used an X-Acto knife. I inserted the blade in between the pieces and wedged a/o cut the pieces apart.

 

First photo shows the pieces, on the left are the bare wood pieces and on the right are the pieces that have had wipe on poly applied.

 

post-20628-0-79255000-1484153994_thumb.jpg

 

 

First was the CA as you can see it splintered some, as far as being hard to separate it was medium I am thinking the splintering was a result of grain pattern more than anything else. The poly treated was was difficult to separate and resulted in lots of splintering.

 

The Titebond on dry wood was very difficult to separate and caused lots of damage. With the poly applied it proved to be very easy to separate and I probably could have used my finger nail to do it.

 

The Weldbond showed no real difference when applied to bare wood or wood with poly on it. Although stronger than Titebond on poly it did not have the adhesion Titebond did on the bare wood. I would say it was slightly stronger than CA on bare wood.

 

post-20628-0-55964600-1484154015_thumb.jpg

 

What's my take on all of this?

 

Bare Wood: Titebond, Weldond then CA.....but it really is so close between these two as to which one should be second

 

Wood with Poly: CA(by a landslide), Weldbond and Titebond....

 

So if you are gluing bare wood to bare wood Titebond is by far the way to go and if you are gluing finished surfaces then CA without question is the choice to go with.

 

 This just what I have found out by doing this very UN-scientific  experiment, I am by no means advising you to change the glue you are using now

 

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I like TITEBOND on bare wood myself.  For most things other than bare wood, I will tend to use WELDBOND.  Both are easily separated using alcohol.  CA requires acetone...yucky stuff.  If I am glueing small parts, such as deck furniture, etc, I tend to trunnel the piece with a wee bamboo peg as well as glue it.

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You did the experiment for the use of PVA on prefinished wood.

Confirming that doing it is not a good idea.

 

It is not a surprise that Weldbond and Titebond yield similar results

on bare wood. Weldbond and Titebond are both PVA adhesives.

A difference may be the pH.

Weldbond   = 5.5

Titebond     = 3.5-4.5

Titebond II   = 3.5

 

Weldbond  is 10 - 100 times less acidic.

With wood the difference may be of no significance.

With cotton or linen the difference may matter but there

are pH 7 PVA products available.

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Nice topic.

I use Gorilla (wood glue, not the foamy stuff), Titebond or Elmer's wood glue on wood to wood. (I have no preference over any one of these last three. Whichever is available at the moment. I haven't found evidence to support an opinion of which outperforms the others)

 

For any other media (most frequently metal to wood) 2 part epoxy is my choice by far. Is it messy? YES!; is it a big waste? YES! is it still the best choice (for me)? YES!.

 

:)

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G'day Don

This is a great topic that you have started.

I found that I mostly used only one glue for everything. BALSA CEMENT.

This glue is very strong, easy to clean off the excess and can be painted or oil varnished over. But it relatively dries quick and hardens in about 8 hours. It takes about 2 minutes to hold two pieces together - example 4 x 1 mm timber held vertical on 1 mm edge against another same size piece.

You can even glue bare timber to preprinted timber. (This bond is not as strong as bare to bare, but it is still quite strong).

havagooday to all

Greg

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Not sure that those glues avail in AUS but I use wood white PVA for most wood to wood. Dries clear no stain. Just have to be patient for drying.

or for decks / second layer planks - Contact Adhesive as per Keith Julier.

Lateral to vertical where strength is needed/ pinned 2 part Epoxy.

Metal to wood or metal to metal CA thick/thin or as designed and invented skin to skin!!!

Plastic - Tarzan's grip or Tamiya model glue

Rope CA / PVA diluted

thibaultron, mtaylor, Canute and 1 other like this

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May seem a silly question but.......... Frames are cut and ready for assembly. On double frames do you remove the lower template paper and glue wood to wood or just glue over the paper?  Using wood glue.

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When it comes to ca glue I like to buy zap a gap and don't trust the cheap brands found in pound shops or dollar stores wherever you may be from as for white pva I have worked in the carpentry business for 18 plus years and buy it by the gallon the cheapest trade five galleon drum I can find and find no difference what so ever

This may be off subject but also when it comes to paint stop being ripped off by hobbie shops selling small tins of sand and seal and varnish it's the same stuff as a builder supply would sell to treat wood

mtaylor, davyboy, coxswain and 3 others like this

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I use different types of glue depending on the job.

For all the planking on the hull and the deck and most of the larger structures I use Jetset rapid white PVA wood glue.

For the strips on the side of the hull I need to know they will stay in place. For these I use Aliphatic Resin. This is as good as CA glue and will be used on other areas that I need a permanent set.

For other areas of the build I use Titebond Premium.

I only use CA in an emergency. I don't like using it on wood I find the resin better. I only use CA on photo etched or brass parts. And even then only if I really have to.

Paul

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Most of these comments are about wood-to-wood joints. I assume this means bare wood. Are there any comments about gluing wood that has laser char? Does the char weaken the joint? I try to remove the char; but there are many areas where that is hard to do.

 

Thanks,

Walt

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Walt, I always try my best to glue bare wood to wood. Even if I have already painted an area and find I have to glue something on I will scrape the paint off.

As for laser char I remove it as best I can. I find that it has cauterised the wood, if that make sense. This has the result of the part being glued none porous  and hard to get a good bond.

Paul

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Hello Les here. Bare wood to bare wood is always the best. CA is always a good choice for quick bonding. But be aware that as it soaks into the wood any bleed out is difficult to sand out. It won't take stain or clear coat as well as bare wood, as the surface is now sealed. PVA can be cleaned up with water. I use a cotton ear swab soaked in water to clean up squeeze out. Use less than you would think. Glueing pre finished surfaces will not hold as well as the adhesive does not have the capability to soak into the surface.

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G'day Les 

I have found that balsa glue is a good alrounder glue. It's even bind to lacquered surfaces and you can be clean the unwanted glued surface away using baby wipes when it's wet, if the gluing is a bit messy. 

Havagooday 

Greg 

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@Paul Jarman

That's mainly right. The Laser changed the structure of the wood. Also sandig the areas will not remove the charcoal. Even if there seems to be nothing left, small amounts will remain. Life's easier

for plastic modelers, they can weld their PS using plastic glue.

mtaylor and Canute like this

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Wood was once a living tree.  It is a highly organized structure of individual cells.  The cells are aligned along the grain of the wood.  Wood glue, such as titebond, works by penetrating the open pores of the wood.  Think of when water raises the grain of wood, it does so by filling the open pores and swelling them.  The strongest joint is attained when the open cells of one piece of wood are aligned with the open cells of the adjoining piece.  So straight grain to straight grain is the strongest joint (the edge of one plank to the edge of the next), gluing grain in one piece with grain in cross direction on the next yields a weaker joint (plank to frame or bulkhead).  Gluing end grain (the end of one piece) to end grain creates a very weak joint.  Anything that blocks the pores (like wipe on poly) or clogs the pores (like laser char or 300 grit sand paper dust) will prevent the glue from penetrating and will create a weaker joint.  So scrape your char, don't sand it.  Use wood glue where it would be strongest, use CA in places where wood glue would be weakest.

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2 hours ago, VACorsair said:

Wow!

 

Just learned more about wood glue than I have in the preceding 63 years!   

 

Amazing what you will find out on this great forum. This is why it is the best around. :P 

Amazing advice John. Really like your explanation.

So i am doing something correct as I scrape the char off with a hobby knife rather than sanding it off.

Paul

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