Why does gorilla glue recommend moistening? - Woodworking Talk - Woodworkers Forum
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post #1 of 27 Old 06-29-2019, 10:31 AM Thread Starter
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Why does gorilla glue recommend moistening?

Iím curious to know the ďwhyĒ about Gorilla glue recommending moistening one surface before using Gorilla glue.

Is it that Gorilla Glue requires moisture to cure? In that case, isnít the 80% humidity in my basement enough to make the glue kick? Would lack of moisture just cause the glue to take longer to cure? Is a long curing time bad?

Doesnít the wet surface impede good bonding?

Iím not necessarily questioning the practice of moistening, just interested in learning more about the chemistry behind it.
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post #2 of 27 Old 06-29-2019, 10:43 AM
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Generally a light misting of water allows you to move the piece into final position by delaying setting.
I would think gorilla is the same.
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post #3 of 27 Old 06-29-2019, 11:37 AM
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Quote:
Originally Posted by Quickstep View Post
Iím curious to know the ďwhyĒ about Gorilla glue recommending moistening one surface before using Gorilla glue.

Is it that Gorilla Glue requires moisture to cure? In that case, isnít the 80% humidity in my basement enough to make the glue kick? Would lack of moisture just cause the glue to take longer to cure? Is a long curing time bad?

Doesnít the wet surface impede good bonding?

Iím not necessarily questioning the practice of moistening, just interested in learning more about the chemistry behind it.
It doesn't make a dramatic difference but it makes the surface more absorbent to wet it. It's like you can pick up more with a damp sponge than a dry one.
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post #4 of 27 Old 06-29-2019, 11:39 AM
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Gorilla Glue is water reacting. Just like silicone caulk, it requires moisture for the reaction needed for it to set and harden. In high humidity areas it sets and hardens from the moisture in the air. In drier climates, it doesn't get enough moisture from the air to set up quickly. Adding moisture to one surface to be joined will speed up the setting and drying action of the glue.

That being said, I have used Gorilla Glue and I don't like the foaming and the mess that it makes. I've gone back to using more traditional glues like Titebond II, III, and Titebond Extend.

Charley
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post #5 of 27 Old 06-29-2019, 12:18 PM
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They say it needs moisture to react ...


The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #6 of 27 Old 06-29-2019, 11:08 PM
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I use original Gorilla glue for gluing brass insert tubes into pen blanks. I like the foaming action, which helps it fill gaps. The slight rubbery feel leaves it less brittle than ordinary CA glue. CA glue is popular for pen inserts. Some people use epoxy.

I moisten the inside of the pen blanks with a wet Q-tip before applying the glue. I have forgotten to wet the blanks a few times, and it made no real difference, although it took longer for the glue to foam and cure. We live in a pretty dry environment and I believe that the natural moisture in the wood helped the glue cure.

For regular woodworking glue joints, I use Titebond III. It is an excellent wood glue. It is waterproof and suitable for exterior use. Even though Titebond III is more expensive than Titebond I or II, it does everything I need, so with Titebond III, I don't need the other two glues.

A very knowledgeable friend just told me that Titebond II and III may not be the best for cutting boards. He shared that the water resistance / waterproofing chemical in Titebond II and III makes the glue elastomeric (more rubber-like) which is not desirable for cutting boards. He recommended Titebond I for cutting boards. It sounded plausible, anyway.

Last edited by Tool Agnostic; 06-29-2019 at 11:14 PM.
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post #7 of 27 Old 06-30-2019, 12:30 PM
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I tried Gorilla glue but didn't like it because of the mess it made. (foaming).
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post #8 of 27 Old 06-30-2019, 03:46 PM Thread Starter
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I completely agree on the foaming. It makes a mess and even though it will fill a gap, the foam has little if any strength.

BUT....

I’ve recently discovered Gorilla Glue Clear. It doesn’t foam and it’s dead clear. I think this stuff might be ideal for gluing pen tubes to blanks.
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post #9 of 27 Old 06-30-2019, 06:07 PM
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Some chemicals need a certain amount of moisture to hasten the curing process. That moisture may even be water.
I am not familiar with Gorilla glue but fairly experienced with CA glue (AKA super glue.

if you get some on your fingers it will just cure out with much notice as to time frame. If you use an Activator, the CA Glue will set up almost immediately. I dont know what is in the activator but most often, the chemical reaction is so fast and furious that it will actually smoke. Now imagine you have a fairly decent cut from a razor on your hand. Not life threatening, but something that a normal person would go and get it stitched immediately. The not so normal person, myself included, would just squirt some CA into the wound and close it up with his other hand. THEN, the quick reaction of moisture - your blood- reacts immediately. The result is SMOKING!. I mean REALLY HOT smoking. It will bring a tear to a grown mans eyes. But.........the wound is closed and within a few hours, you will be able to use the wounded hand without too much pain. I have a few of these scars which are no more visible than if it were stitched.

Just trying to add a little more insight to the topic.

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post #10 of 27 Old 06-30-2019, 09:05 PM
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I stopped using Gorilla glue because of the foaming. Nasty stuff. Question, does the clear verision foam?
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post #11 of 27 Old 07-01-2019, 08:38 AM Thread Starter
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Quote:
Originally Posted by DesertRatTom View Post
I stopped using Gorilla glue because of the foaming. Nasty stuff. Question, does the clear verision foam?
No, the clear doesnít foam. Itís viscosity is similar to Epoxy. It seems more flexible than Epoxy. It seems good for bonding dissimilar materials. Iím using it to bond glass to wood.
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post #12 of 27 Old 07-01-2019, 10:16 AM
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I have been trying out different glues for the brass inserts in pen kits. As I said above, I use Original Gorilla Glue for most pens. Last week I tried White Gorilla Glue and Clear Gorilla Glue for brass tubes in pen inserts.

White Gorilla Glue is a polyurethane glue that foams and dries white. From my testing, I found that White Gorilla Glue was runny when compared with Original Gorilla Glue. That runny-ness caused the glue to drip from the brass tube before I could get it inserted in the blank. The regular Gorilla glue is thicker and gummier and doesn't drip. As advertised, the White Gorilla Glue cured faster than Original Gorilla Glue. It dried white, which I like. I may switch to it for pens because of the faster cure and white color, but I don't like the drippiness when applying it.

Clear Gorilla Glue is a silane-based glue. It is unlike other glues on the market. At the recommendation of a friend, I tried it on one special, challenging pen blank. It goes on clear and dries very clear. It does not foam. When dry, it has more of a rubbery feel than a "hard surface" feel. Storage is annoying: keep it cool, but keep it exposed to light.

White Gorilla Glue was the hardest to find on a local store shelf, but my local Walmart carries small bottles of Original Gorilla Glue, White Gorilla Glue and also Clear Gorilla Glue (a silane-based glue). They were the only local store I found that sells all three products.

Pay attention to the package labels: Gorilla also makes Gorilla Wood Glue, which is white, and several types of Gorilla Super Glue, which are clear. Do not confuse them with White Gorilla Glue and Clear Gorilla Glue.

P.S.
I want to add that these small bottles of Gorilla glues are very expensive at $6 for 2 oz. They are "cheap" for me, because I use very small amounts for pen making. A 2 oz bottle will easily glue 75 - 100 pens, but it would not be cost effective for a panel glue-up. I buy the smallest bottles I can find because they have a relatively short shelf life.

Last edited by Tool Agnostic; 07-01-2019 at 10:34 AM.
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post #13 of 27 Old 07-01-2019, 10:30 AM Thread Starter
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Quote:
Originally Posted by Tool Agnostic View Post
Clear Gorilla Glue is a silane-based glue.
I've never heard of that one. Can you expand on that a bit?
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post #14 of 27 Old 07-01-2019, 11:12 AM
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Quote:
Originally Posted by Tool Agnostic View Post
[...] Clear Gorilla Glue is a silane-based glue. [...]
Quote:
Originally Posted by Quickstep View Post
I've never heard of that one. Can you expand on that a bit?
I had not heard of it until a friend recommended Clear Gorilla Glue for a special, challenging pen blank that I am working on. Before I bought the Clear Gorilla Glue, I did some internet research, and came up dry. I quickly figured out that Clear Gorilla Glue is different than other glues, but it was not easy to find the type of adhesive it is. Gorilla's website does not really explain it. The Manufacturer Safety Data Sheet (MSDS) was no help. I called Gorilla customer service and asked. Gorilla's customer support person mentioned silane, which was the clue I needed.

I am not a chemist. I tried to pay attention in chemistry class, but it was a long time ago. There isn't much on the web that I can understand about silane-based adhesives. Here is the best description that I found:

http://www.adhesiveandglue.com/modified-silane.html

Functionally, the cured silane-based glue has a rubbery texture that is similar to the original Gorilla polyurethane glue I have been using. I like the rubberiness (elastomeric) properties because it might absorb the shock better if a pen is dropped on a hard surface. That is why I prefer polyurethane (and now silane-based) glues for brass pen inserts, compared with CA and typical epoxy glues, which are more brittle when cured.

Sorry I don't know more. I hope this helps.
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post #15 of 27 Old 07-01-2019, 01:18 PM Thread Starter
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Thanks for that Tool Agnostic, that's valuable information. I kind of stumbled on Gorilla Glue Clear. Time will tell, but for what I know now, its flexible nature combined with not expanding, seems to make it ideal for bonding dissimilar materials.

I'm curious about the "store in a cool place with exposure to light" storage instructions. Maybe it could be kept in the fridge since we really don't have scientific proof that the light really goes off when you close the door. :)
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post #16 of 27 Old 07-02-2019, 12:48 AM
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Quote:
Originally Posted by Quickstep View Post
Thanks for that Tool Agnostic, that's valuable information. I kind of stumbled on Gorilla Glue Clear. Time will tell, but for what I know now, its flexible nature combined with not expanding, seems to make it ideal for bonding dissimilar materials.

I'm curious about the "store in a cool place with exposure to light" storage instructions. Maybe it could be kept in the fridge since we really don't have scientific proof that the light really goes off when you close the door. :)
You're welcome. I see Clear Gorilla Glue as an excellent one-component replacement for two-component clear epoxy glues when used as adhesive, not as a structural filler.

Clear Gorilla Glue yellows over time in the dark. It needs the light to stay clear. I don't remember where I learned it, but I think it was the phone conversation with the Gorilla customer support person.

Last edited by Tool Agnostic; 07-02-2019 at 12:53 AM.
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post #17 of 27 Old 07-02-2019, 04:40 PM
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The term I read was "cross link". The article said that the Gorilla glue continues to cross-link and continues to improve in strength. The water is supposed to accelerate that process.
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post #18 of 27 Old 07-02-2019, 11:45 PM
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I just found the perfect use for Clear Gorilla Glue. I used it to glue two short wood pegs to that fibrous backing on hardboard. The hardboard is only 1/8 inch thick, so it is too thin for screws. I wasn't sure that the glue would hold, but it worked perfectly.

Background information you can safely ignore:

I made a small hardboard pad with two pegs that line up with the dog holes in a workbench vise. The workbench usually has a hardboard cover to protect it. The vise was 1/8 inch lower than the top, so I made a hardboard cover for the vise that stays in place with the two pegs. It may be "vise abuse", but sometimes I open the vise to drill through the gap with a handheld drill. Now it is easy to match levels when the workpiece rests on the vise.
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post #19 of 27 Old 07-03-2019, 06:14 AM
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Short answer, the polyurethane used for the adhesive requires moisture to kick off the polymers cross-linking process. Think of it as something like a 2 part epoxy, where the 'resin' portion is the gorilla glue and the 'hardener' is the water. Since the water is required for curing, the makers of GG probably recommend dampening the surfaces to ensure the water is there. As people have attested, its possible to skip this step and still have the glue cure with just atmospheric moisture, but 'possible' and 'will' are different things, and the instructions have to have a method that works 99% of the time.

Also, the "cool, dark place" recommendation for storing the clear stuff is likely to prevent UV degradation from making it cloudy, as well as slow down unintended curing. Plastic is permeable to moisture and heat can do weird stuff to glue, and cool air is both lower in moisture and heat

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post #20 of 27 Old 07-03-2019, 09:19 AM
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The bottom line though is gorilla glue is a poor adhesive only good where parts don't fit so well. The foaming action fills those gaps. On well fitted parts there are much better adhesives a person could use.
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