This is the second part of a series (I did epoxy before) in which I will review various glues etc.
Superglue / cyanoacrylate is a staple in almost all neuroscience labs. While there are some applications for super glue, in the lab setting there are usually better glues for the job.
- Thin films can cure very rapidly, this is the main advantage of superglue, but one that is not often needed in lab.
- Not great at filling gaps. Thick globs of gap-filling superglue take forever to cure, negating the main advantage of superglues.
- It is not immediately obvious whether a glue joint has cured.
- Comes in liquid form, can make thin coatings and fill tiny cracks.
- Gives off cyanoacrylate fumes, these are irritating to mucous membranes, and generally pretty reactive. You can’t for example use super glue on some plastics (acrylics get seriously messed up by super glue) and particularly you can not use it around any coated optics.
- To re-iterate, keep super glue away from optics.
- Not very shelf-stable, test older glue on test pieces before ruining your part with expired non-curing glue.
- Cures to a pretty brittle solid, not particularly useful in anything but thin coatings.
- Great at adhering to water-containing materials, such as skin, bone, etc.
- Cures faster in presence of extra humidity, so breathing on it can help.
- Generally cures by reacting with water vapor from the air, so thick films can take a while to cure. Don’t be fooled by the outside of a joint looking done, the center will cure after the surface.
- You can get special accelerants to cure superglue much faster and in absence of water. If you have methyl methacrylate at hand (for using with old-school dental acrylic cement), this seems to work in a pinch, but is in itself a source of very nasty fumes and requires a fume hood or other safety measures.
- Can be removed with acetone, ethanol does not work amazingly well.
How to use:
- Fix parts in place and apply small amount of glue to the gap, or apply thin film to one side, and hold in place.
What to buy:
- Get a bottle of some thin and medium-thickness stuff, or grab ~20 of these tiny one-time-use tubes. They dry out after the first use anyways so you may as well go all in on the one-time use stuff.
What to use instead:
- If you can stand the effort of a bit of mixing and can wait 5 minutes, epoxy is usually a better choice for things that you need to have good mechanical stability.
- If you have a gap you need to fill with the glue, need speed, and can handle a somewhat flexible, weak and messy looking joint, consider using hot glue instead.
- If you have well-aligned, gap free surfaces that you need to glue, or multiple small glue joints done quickly, and the fumes aren’t an issue, go ahead and use superglue.