Sticky business
Five glues I always have on hand
There is a seemingly unlimited variety of adhesives, with many unique formulations, each often designed for a specific purpose. There are glues for wood, paper, cloth, leather, plastic, and metals. Indeed, for nearly every material, there is a glue for it. Plus, many types of glue can bond different materials together, such as plastic to wood, or wood to metal. With all these options, it's easy to get stuck sorting through for the right adhesive. Fortunately, I've compiled a short list of go-to glues every maker should have on hand.
PVA glue (a.k.a. white glue, wood glue)
What it is: polyvinyl acetate, a vinyl polymer that air dries to a semi-solid, rubbery consistency
Uses: porous materials such as wood, paper, leather, and cloth
PVA glue is nearly everyone's first experience with an adhesive (think "Elmer's School Glue"). This non-toxic glue is excellent for all kinds of crafts and is safe for kids. Plus, it dries quickly and is relatively forgiving. Another reason it's great for kids (and all of us) is that PVA easily washes from hands and clothes with soap and water. But don't be fooled by this glue's gentle nature; a thoroughly dried (cured) PVA bond is often stronger than the glued material.
Many specific PVA formulations exist, such as those explicitly made for wood. I have both regular white (all-purpose) glue on hand and a few different formulations of wood glue always available. The latter have additives that make them more impervious to water, but most PVA glues will work well for most porous materials. I do have a specific PVA for leather, but I suspect any old white glue would work well here, too.
CA glue (a.k.a. super glue)
What it is: cyanoacrylate, a fast-curing polymer with a strong bond
Uses: lots - paper, plastic, wood, metal... even skin.
CA glue is nothing short of miraculous. This stuff bonds almost everything and works particularly well for detailed applications such as modeling and repair work (e.g., broken ceramics or plastic parts). While the bond is very strong, it does not have a lot of "sheer strength," so applications expecting a lot of twisting, bending, or sliding are not necessarily the best use of CA glue.
I employ CA glue when working on most projects where speed is paramount. Model making, repair jobs, and sometimes even woodworking all benefit from the quick drying time. But you don't sacrifice strength even though it's quick. Anyone who accidentally bonded their fingers with CA glue will attest to the bonding power this truly "super" glue has. Speaking of skin, I’ve been known to “repair” minor cuts using CA glue (although I am by no means offering medical advice here).
I keep a couple of different formulations on hand, including thick or "gel" CA glue, useful in gap-filling applications and thin for those aforementioned repair jobs. Having a can or bottle of activator is also useful; these agents speed up the already fast curing time of CA glue and can enhance the sheer strength of the bond.
Two-part epoxy (a.k.a. epoxy)
What it is: epoxy resins mixed with a co-reactant before application
Uses: often a structural adhesive but can be used in a number of ways; bonds plastics and metals as well as a variety of porous materials
If you need a super-strong bond that'll take abuse, two-part epoxy is your glue. A common name-brand version, J-B Weld, refers to it as a "cold-weld" suitable for attaching or repairing even metal parts. While not a proper weld, the stuff is strong and often forms nearly unbreakable bonds. I once repaired a broken toilet with J-B Weld, and it held water like new.
I keep several types of epoxy on hand, each differing in their overall strength and cure time. Quick-set epoxies cure in less than five minutes and form moderately strong bonds. Standard set epoxies take longer to harden but offer superior strength and durability. Clear epoxy is also available and is excellent for applications that will not be finished or painted after gluing.
Hot-melt adhesive (a.k.a. hot glue)
What it is: thermoplastic adhesive, melted before applying and then allowed to cool
Uses: forms simple, moderately durable bonds between paper, wood, plastic, cloth, and foam
Hot glue and their dispensers - hot glue guns - make the craft world go round. Hot-melt adhesive is a quick and easy way to connect things and can also serve as a gap-filling compound or even an insulation in electronics work. The beauty is in its simplicity - hot glue needs only cooling to reach its full strength. That said, hot glue is not all that strong, so don't expect it to serve any major structural purpose. But in the right application, reaching for the hot glue gun is a quick and easy way to get things stuck.
I use hot glue when making prototypes or short-lived projects like costumes. I'll use any of the other adhesives listed here if I need a more permanent bond. But hot glue is fantastic when brainstorming builds in model form and can glue together corrugated cardboard quite well. I also occasionally use it to "lock" small nuts on bolts that'll receive a bit of vibration. It's less messy than a thread-locking compound and more easily removed later.
Contact cement (a.k.a. impact glue, contact glue, neoprene glue)
What it is: fast-acting, neoprene-based polymer with extremely high bond strength
Uses: laminating and attaching almost all materials, including wood, plastic, foam, metal, and glass
Contact cements have been around for decades and were the first "super" glue before super glue (CA glue) became popular. One of the strongest fast-acting adhesives, contact cements excel in lamination and can cement disparate materials, such as wood and metal. The adhesive must be applied in thin, even layers to both surfaces and allowed to air dry before sticking the parts together. The process looks counterintuitive; if you put the wet pieces together, they don't stick. But when dry, look out. You only get one chance with contact cements; once the parts are stuck, it's virtually impossible to reposition them.
I always keep two types of contact cement on hand: brush-on that comes in small jars (various manufacturers) and spray-on, specifically 3M's Hi-Strength 90. I use the brush-on when joining small parts or edges where overspray will be problematic. But for almost any lamination job, I reach for the 90. This stuff is arguably the best spray adhesive available, but it requires patience and exactitude to use well. As mentioned, you only get one shot with contact cement, so lining up two large sheets of something to laminate together using 3M 90 is daunting. But if and when you get it right, it will be a job done right for the ages.
Okay, I hope this list of glues helps you stick your next project. Have a favorite glue yourself? Any other suggestions? Let us know in the comments!
Until next time.
JRC