Mad About Science: Polyvinyl acetate

By Brenden Bobby
Reader Columnist

Don’t be scared away by the title, you’ve encountered polyvinyl acetate on a daily basis. What is it? Could it be some kind of noxious chemical polluting our waterways, gassing unsuspecting civilians, melting the flesh from our bones?

No. It’s Elmer’s glue.

PVA glue is one of the most versatile and accessible adhesives available. Beyond its obvious uses in classrooms around the world, it is employed virtually everywhere. From construction to book binding, polyvinyl acetate is one of the most useful tools in our arsenal.

Finding in-depth information about the manufacture of polyvinyl acetate was admittedly difficult.I did manage to suss out that it’s the result of a reaction between a chemical reaction of ethylene and acetic acid (a component of vinegar), along with oxygen and a palladium catalyst. 

You’re going to have to ask your chemistry teacher for a more thorough explanation if you want one; because, admittedly, that was one of my weakest subjects in high school.

PVA is often mixed with water to help efficiently disperse the polymer across an area. Adding water to Elmer’s glue thins it out, but it makes it exceptionally good at seeping into cracks and crevices to completely seal an item without leaving big chunky bits of dried glue.

This function of PVA glue is most commonly seen in paint. Latex-based paint is pigment suspended in a mixture of polyvinyl acetate and water. As the water evaporates from the glue, the PVA forms an extremely thin and translucent polymer layer to trap the paint below. It’s a lot like throwing a sticky clear tarp over your garden.

This form of glue is vastly different from another form of powerful glue: superglue, or cyanoacrylate. PVA primarily dries and seals as water evaporates from it, leaving a dry sealant effect over things. Cyanoacrylate instead reacts with water, primarily water in air, to create a rapid polymerization reaction to grip anything it comes into contact with. These features make for two distinctly useful tools when applied in different ways. PVA glue does its best work when it comes in contact with porous surfaces, such as paper, wood or plaster. Superglue effectively binds two smoother surfaces together, such as plastic or resin.

Bonus fact: If you are struggling to bond two objects together with superglue, try dusting one surface with a little bit of baking soda. The baking soda causes rapid polymerization of the cyanoacrylate. This can be used to fill in the heads of stripped screws, which you can tamp down with your desired sacrificial bit to rip the screw right out with a cordless in seconds.

Bonus bonus fact: Never put superglue in the oven. While PVA is a thermoplastic and will melt when exposed to heat, superglue will break down and create a poisonous cyanide gas.

PVA has surprising uses beyond construction and crafting. Library nerds rejoice, for PVA is the primary adhesive responsible for binding your books. The fact that it’s not acidic also benefits the book binding process, as other glues would react with the paper and destroy your favorite book over time.

The process of book binding could fit into its own article, but it’s worth exploring a little here. It’s not uncommon to have sections of a book threaded together before its total assembly, particularly in important or rare books with a limited number printed. These bundles are stacked together and slathered multiple times on the spine with PVA glue. Have you ever checked a well-read book out from the library and witnessed little chunks of yellowish substance flaking from the spine? This is glue, and you should probably let a librarian know.

We have a dedicated mender for our library books here at the library, but we cannot offer this service to the public. We have hundreds of thousands of books in our collection and maintaining them is a massive undertaking. If you’re looking for a dedicated mender that could fix your well-loved tome, a librarian can redirect you to a specialist that can perform it for a fee, but the library won’t be able to do the mending for you.

Do you enjoy licking envelopes? Envelope sealant has a distinctive taste, and while your neighbor may view your love of letter-licking as something obscene, you can let them know it’s not any different from chewing gum. PVA is used in both of these applications, in addition to cigarettes — though let’s be honest, a long life of paper cuts on your tongue beats an abbreviated life of coughing up a lung.

My personal favorite use of PVA glue is used to seal flocking grass used in miniature terrains. Elmer’s glue or Mod Podge mixed with water in a spray bottle gets spread over a foam block covered in flocking, tile grout and whatever else I’ve cobbled together to mimic life at 28-millimeter scale. The water covers everything, evaporates and leaves a nice sealant over the piece that keeps it durable and somewhat waterproof. This is especially important for modular pieces that link together with magnets, like a teeny-tiny Minecraft world. 

Crafters, if this is your cup o’ tea, you know how to reach me.

Finally, PVA has one more amazing application. When mixed with borax and saline solution, something happens to the glue. It begins to get very sticky, stretchy and just plain… weird!

Slime is a family favorite, and easy enough to make at home with these simple supplies. It can even be done with baking soda in lieu of borax and liquid starch in lieu of saline solution.

All of these supplies can be found at a department store for next to nothing, providing an evening of scientific experimentation and fun for the whole family.

Stay curious, 7B.