Super glue really does deserve its name – a 1-square-inch bond can hold more than a ton. It looks like water, so what makes it so powerful? The primary ingredient in super glue is cyanoacrylate. (C5H5NO2 if you’d like to mix up a batch.) That explains its other commonly used name; CA glue. Cyanoacrylate is an acrylic resin that cures almost instantly when triggered by the hydroxyl ions in water. Almost any object you might want to glue will have at least trace amounts of water on its surface. Even air contains water in the form of humidity. As super glue cures, it forms long, strong chemical chains, which bind the two surfaces together. Super glue forms an almost unbreakable, waterproof bond within seconds.
Almost any material or combination of materials can be bonded with CA glue; everything from wood, aluminum, steel, neoprene, rubber, nitrile, ABS, PVC, phenolic resin, and most plastics, to vinyl, leather, and many other materials. Materials that won’t bond well with super glue include teflon, polyethylene, polypropylene, materials with acidic coatings, and some plastics that are very oily and flexible. Glass will bond, but not reliably.
CA glue can be liquid and runny as water or thick like a gel. It helps to match the viscosity of the glue to the materials you want to bond. You want to use the thinnest glue that will fill the gap between the pieces you want to bond. So for a clean break on a piece of china, the gaps will very small because the pieces fit tightly together. If you used a gel-type CA glue, the parts would not fit tightly and you would see a gap. On materials that are more porous or have rough surfaces like bare wood, you will need a gel glue to fill the gaps and make a solid bond.
Be sure to use just the right amount of glue. You don’t need to cover the surface with a thick layer or even cover the whole surface. To bond two pieces together a spiral pattern or a series of dots will work just as well. The downside to using too much glue is that it may not cure completely. Thin layers are always better. If you are filling a crack, you should continue applying glue in layers until it no longer wicks into the crack. The layers will ensure the glue cures completely. A larger gap may require a gel but apply it in layers: a large blob of glue may seal itself and never cure.
If the glue isn’t curing there are several things you can do. If there isn’t enough moisture to activate the glue you may need to moisten one of the surfaces or use an accelerant. Oils or other contaminants can also slow the curing – be sure your bonding surfaces are clean.
Whether you call it Super Glue, Krazy Glue, Instant Glue, CA Glue or any other name, used correctly, it can really be super!
