How Come all the really good glue expands

I broke the heel on my favorite shoe. So at the store I get my hands on : “THE TOUGHEST GLUE ON THE PLANET” it really says that on the bottle. The chick behing the counter says don’t use too much it expands. So I’m wondering, why does all the really really good adhesives and seals expand? BTW I used too much and had to scrape the excess off my shoe.

Perhaps epoxy would work better…

The more glue gets in contact with the two surfaces, the stronger the grip (if you can get both hands on the peanut butter jar lid while somebody else gets two hands on the jar, it’s easier to turn because you have more torque). If the glue expands, it covers more area rather than the little dab you put here or there.

Sorry let me explain. I mean what chemical/s are used to make the stuff expand? Then of course the next questions is why doesn’t it expand in the bottle?

You’re talking about Gorilla Glue, right, Tia3child? Here’s its MSDS – Gorilla Glue is a polyurethane-based adhesive, primarily intended for use with wood. The expansion is due to a chemical reaction that occurs as the glue cures – note that it requires a bit of moisture to cure properly (you did dampen at least one side before gluing, right?)

Hm? I’ve glued many a thing to many another… I’ve not experience “expanding” glue.

My personal favorite is two-agent epoxy putty. This stuff comes in stripes of blue and yellow. You cut off a little, and knead it together until it turns a uniform green. At that point, you have about ten minutes to use it, as it slowly hardens. This stuff is GREAT! Top notch! Highest recommendation! You can use it to fill cracks, or to stick things together.

What sort of shoe? If it’s a high-heel, forget about it. Take it to a professional, who will drill holes in the shoe and the heel, and insert a steel post. There is NO glue that can cope with the stresses on the heel of a high-heel shoe.

If it’s a low heel shoe, you might get by with epoxy, but I’d want to use nails also. Again, take it to a real cobbler.


Thats exactly what I was talking about. Gorilla glue and yep I had to wet it first.

The shoe is a High Heel Shoe but its a block heel and I wore them today and they held up fine using the Gorilla Glue.

Thanks for the Link.

Please be careful. I know that stuff is extremely strong, but the stresses in a heel are high and the cross-sectional area is small (unless you have a very uneven break).

I imagine it will hold up fairly well, but if it were my wife’s shoe, or my daughter’s, I would put a pin in it, too.

Sorry, I missed the “block” part. Never mind.

to expand on 3waygeeks answers. The glue contains isocyanates. These react with moisture to produce carbon dioxide gas (which slighlty foams your glue expanding it) and an amine. The amine then reacts with other isocyanates crosslinking everything and setting the glue. It is the same reaction used to make make polyurethane foams.

Isocyanates make good glue because of all the polar groups that bond well to things. However the foaming reaction will actually weaken the glue slightly depending on application - I would put my life on an epoxy glue if push came to shove