Cyanoacrylate Consistently Curing Adhesives
Cyanoacrylate (also called CA, instant adhesives or super glue) are very reactive and require stabilizers to remain liquid. They cure when the minute amount of moisture on the surface of the parts being bonded deactivate the stabilizers and allow the material to polymerize.
More Cyanoacrylate Doesn’t Equal Stronger Bonding
Use only enough adhesive to cover the bond joint. When bonding with cyanoacrylates, less is best.
It is also important to note the gap fill capabilities of the CA adhesives.
Exceeding the maximum gap fill recommendations of the manufacturer can result in incomplete cure and low strength.
Adding moisture or water after attempting to cure will not produce an effective cure through a larger than recommended gap. However, cyanoacrylate bond accelerators are available to cure the surface of the cyanoacrylate and to allow a stronger bond through larger gaps.
Accelerators can also be used to treat porous or acidic surfaces prior to cyanoacrylate bonding.
Treating a porous surface with accelerator causes the adhesive to cure before it can wick into the porosities.
For consistent bonding:
- Use only as much adhesive as is needed to cover the bond area.
- Maintain a consistent gap between the parts
- Automate the process or use fixtures to assist workers in getting parts assembled accurately to avoid repositioning once cure has started.
- Maintain consistent relative humidity for bonding. The relative humidity in the room affects the level of moisture available on the surface of the parts. Or if absolute consistency isn’t a problem, expect slower cure speed in the winter if the heat is drying and faster cure during humid summer days.
- Temperature also plays a role in cyanoacrylate bonding – products will cure faster at higher temperature.