1. Cyanoacrylate: An overview
Cyanoacrylate adhesives (or commonly referred to as “CA” in shorthand) are one of the fastest setting adhesives available today. A variety of formulations exist that offer setting times that vary from just one or two seconds to over a minute. In general, they require no clamping, so you can simply hold parts in place until the glue sets (in manual fixturing applications). CA monomers (liquid, uncured state) will polymerize (cure, solidify) rapidly in the presence of moisture on the substrate and in the surrounding ambient atmosphere. Once the polymerization process begins, it continues on its own, making it a true one part self-curing adhesive.
Cyanoacrylates offer an excellent and very robust bond due to the long polymer chains cross linking between the mating surfaces. CAs will bond to a variety of materials including rubber, plastic, metal, ceramic, wood, etc. CA’s can be used over a wide temperature (-40 F to +250 F) range that suits most applications. In all cases, CA forms a permanent, waterproof bond, but you can reverse it with high heat (above 350 degrees F) or a special debonding solvent such as acetone or nitromethane.
- Fast setting or where clamping is impossible or not ideal
- Maintenance, repair and overhaul (MRO) applications
- Ideal for rubber and engineering plastic bonding applications
- When aesthetics are important and speed of assembly is critical
- Bonding dissimilar materials
3. Out of the Ordinary Uses (Some fun facts)
Cyanoacrylates have long been used for very unusual applications including:
- Developing fingerprints in forensic science (crime scenes)
- Stabilizing fragile fossils during archeological digs
- Repairing the crushed shell of a live tortoise
- Securing plastic worms onto fish hooks
- Mounting saltwater coral frags and colonies to reef rock and plugs
- Strengthening and sealing granular 3D printed model
4. Using the Adhesive
There are many assembly methods when using cyanoacrylates. For manual applications, you need to start with a clean, dry surface. You then apply CA to one of the parts, then quickly press the parts together and hold them until the glue sets, usually anywhere from a few seconds to up to a minute. Don’t spread out the drop or bead, but instead let it squash when you join the parts.
Use the smallest amount you need. Normally, one drop covers one square inch, but you’ll need more on porous surfaces. Excess glue does not add more strength. CA cures slower on some surfaces, but you can use an accelerator to overcome that.
It is always recommended to wear disposable plastic or rubber gloves (non-woven fabric style) and goggles to keep the glue off your hands and out of your eyes. CA is a bit like cutting onions in that the fumes can be irritating to your eyes and lungs, but not particularly harmful. However, it is flammable. In addition, it will stick to skin, so be careful not to get the adhesive on your skin.
6. Storage and Shelf Life
The shelf and storage life of CA’s depend on the size of the container. Smaller amounts have a shorter shelf life than larger ones. A bottle will last at least a year at room temperature. Do not refrigerate opened containers as that can clog the tip and make the glue harden in the container. You can double the shelf life by freezing, but only unopened bottles. Let them warm to room temperature before you open them and don’t refreeze them.
Other Important Information about cyanoacrylate’s
- They are ideal when no clamping is required
- Rapid cure time under a minute
- Sustainable and waterproof
- Submersible in water
- Apply to one surface that is to be matted to another
- Neither expands nor contracts while curing
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