Why does super glue work better with less?

Factual Questions
1

If you put on too much super glue, you get a much weaker bond than if you put just a couple of drops down. Why is this?

2

There is a better air to glue ratio if you use a small amount.

Better to use Epoxy. Now, thats a strong glue that you can use more of :slight_smile:

3

Two guesses:

  1. The glue sticks to other things better than it sticks to itself. Adhesion may be stronger than cohesion for the glue

  2. Large amounts of glue result in pockets that don’t dry properly, which weakens the hold.

4

SuperGlue is an anaerobic adhesive. That is, it sets only in the absence of air. When the bond line is very thin, virtually all of the air is squeezed out and all of the adhesive sets forming a very strong bond. When the bond line is thick, there will be some air mixed in and that part of the adhesive that is adjacent to air will not set.

Haj

5

When you use superglue to bond two materials, there are 3 bonds to take into account, the surface-glue bond on each side and the bond holding the glue together (glue-glue if you like). Superglue has an extremely high surface to glue bond, but the glue adheres to itself less strongly, therefore the less glue forming this layer, the stronger the overall bond.

6

>> SuperGlue is an anaerobic adhesive. That is, it sets only in the absence of air. When the bond line is very thin, virtually all of the air is squeezed out and all of the adhesive sets forming a very strong bond. When the bond line is thick, there will be some air mixed in and that part of the adhesive that is adjacent to air will not set.

hajario, stop making stuff up. As the briefest net search will tell you, super glue (cyanoacrylate) sets with humidity from the air. Air, per se, has no effect one way or the other but the humidity in the air is what makes it set. So, in that sense, air is necessary.