To the glue factory!

Although this picture looks like a still from the movie "Black Beauty" it's actually a re-creation of a common horse nightmare. Running, endlessly running, along a beach, hoof-deep in an advancing tide of glue ...

Amy and I had a discussion the other day (I spoke, she tolerantly listened) which eventually led to my post on whether or not you had to wash an organic apple. One of the questions that came up concerned the little stickers that grocery stores put on produce. When you have to pick a sticker off the skin of an apple, what kind of adhesive is left behind? And, if it’s organic produce, is the glue used in the sticker organic, too?

Because I haven’t yet worked up my nerve to call 1-800-SAFEWAY (that’s 1-877 in the US) to find out about what I’ve started to mentally call “The Organic Glue Dilemma,” I came up instead with various possible scenarios:

1. It could be regular old glue. Just like if you buy organic produce, you don’t have to put it in an organic bag (although, really, you could/should).

2. It could be some kind of natural glue, which could also be organic.

Normal glue is based on yucky things like polyvinyl acetate. No thanks. But didn’t they once ship horses off to the proverbial “glue factory.” Don’t they, you know, make glue there? And, supposing you had an organically-fed horse, which you turned into glue, wouldn’t that make it organic glue?

And, to be honest, shouldn’t a glue made from animal products be edible? I’ll even include bone and hoof here, because if you can nibble at your fingernails, you should be able to eat a hoof. See also: gelatin.

Then I did some research. I found out some interesting things, like that organic apples aren’t waxed post-harvest, but that apples produce some natual wax of their own. Also, that the glue used in stickers is a food-grade glue, so the government thinks it’s okay for you to consume it.

I also found out an awful damn lot about horse glue. Turns out that horses (and other livestock animals) are regularly slaughtered and rendered in Canada — many horses are shipped up here from the States, which only recently legalized horse slaughtering again. Horsemeat is shipped overseas to countries that have a taste for it. It’s also used in zoos, to feed carnivores like lions and tigers (and bears? oh my!). Some of it probably goes into pet food. And yes, some of the connective tissues are rendered into what’s called “hide glue.”

Hide glue has important properties that make it different from regular glue. Says Wikipedia:

Hide glue creates a somewhat brittle joint, so a strong shock will often cause a very clean break along the joint. In contrast, a joint glued with PVA will usually break the surrounding material, creating an irregular, difficult to repair break. This brittleness is taken advantage of by instrument makers. For example, instruments in the violin family require periodic disassembly for repairs and maintenance. The top of a violin is easily removed by prying a palette knife between the top and ribs, and running it all around the joint. The brittleness allows the top to be removed, often without significant damage to the wood. Regluing the top only requires applying new hot hide glue to the joint. If the violin top was glued on with PVA glue, removing the top would require heat and steam to disassemble the joint (causing damage to the varnish), then wood would have to be removed from the joint to ensure no cured PVA glue was remaining before regluing the top.

Hide glue also functions as its own clamp. Once the glue begins to gel, it pulls the joint together. Violin makers may glue the center seams of top and back plates together using a rubbed joint rather than using clamps. This technique involves coating half of the joint with hot hide glue, and then rubbing the other half against the joint until the hide glue starts to gel, at which point the glue becomes tacky. At this point the plate is set aside without clamps, and the hide glue pulls the joint together as it hardens.

And now you know!