In our last blog, written by Megan Freeman, she highlighted our Adult Survival Immersion class making a big batch of pitch glue. We have made pitch glue in our Homeschool Naturalist Kids' class, as well. One of the first questions I get when I go over the ingredients of this sticky substance is "What do you put scat in it for??"
This is a great question. And while many people forgo the herbivore scat step in pitch glue, I've found its addition to a batch to help more than hinder the texture and efficacy of the final product. But first... What is pitch glue?
Pitch glue has been used as an adhesive since before Homo sapiens. It is theorized that Neanderthals were the first to use Acacia resin as an adhesive for hafting tools. But research is consistently uncovering older and older examples of "inventions" we thought were new, so perhaps its use goes much further back. It is also used to fill gaps in woodworking projects, to seal vessels like baskets for waterproofing purposes, and as a general adhesive. Throughout history, the resin from various trees (Birch Betula sp., Pine Pinus, Acacia, Cherry Prunus and more) has been used in this concoction. Of course, the resin itself is sticky as-is. But human use, as well as scientific evidence, has shown that adding a filler, or loading agent, increases the toughness, waterproofness, and malleability of the glue significantly. This is where the variation of historic and modern recipes abound... What is the best filler ingredient for making pitch glue?
It depends on who you ask. Historically and regionally, it varies. Examples of fillers include ochre, dry clay, sand, quartz grains, dry herbivore scat, sawdust, charcoal, and beeswax to start. The quality of each has a unique impact on the final product. As does the resin. I've noticed that even the hardness of the pitch (or plant resin) itself can change a batch of pitch glue for better or worse. I find that fresh, still-mushy resin creates a less-brittle glue. It is generally agreed upon that whatever filler(s) one uses in their pitch glue, it should be very dry, finely-ground, and inherently be made up of varying particle sizes (this increases the adhesive toughness of the glue).
We usually use 2 fillers: dry, ground charcoal and very dry, ground herbivore scat (deer, elk, or rabbit). The charcoal gives the glue a wonderful structure and malleability and the scat adds to this, while further increasing the adhesive strength and the malleability of the glue. Could you leave out the scat? Sure! I have personally found that this leaves you with a more brittle glue in the end. But I encourage anyone wanting to try to experiment and figure out their own ideal glue concoction.
The recipe for pitch glue that works best for me is half resin (usually Ponderosa or Lodgepole Pine here in Central Oregon) and half filler, with a little more charcoal filler than scat filler. To make this, you'll need these:
Tools and Ingredients
-A double boiler: 1 Soup pot with 1.5" of water + 1 metal bowl that sits well in the pot, but above the water line. This bowl will be virtually un-clean-able after this project. So plan for that. Alternatively, 2 tin cans can be used in the same way, but disposable.
-A sturdy stick (diameter of 1 or 2 adult fingers) for stirring and to be your "pitch stick." You'll need several pitch sticks for larger batches.
-1 part Resin (Pine, Birch, Cherry, etc)
-1 part Charcoal (grind it up into a fine powder using a mortar and pestle or by crushing in a plastic bag)
- 0.5-0.75 part Elk, Deer, or Jackrabbit scat. This should be very dry, almost grayish brown in color. Grind it up into a fine powder.
Instructions
1) Put the double boiler on the stove on low or on a bed of coals.
2) Add the resin to the bowl on the boiler. Let it soften to liquid status, stirring regularly. Don't let it get too hot. This will make for brittle pitch glue.
3) Once the resin is melted, add in the charcoal and stir until combined. using a stick, pick out any heterogenous chunks of charcoal you find in the mixture.
4) Mix in the scat bit-by-bit, testing the texture occasionally to gauge how much to add. You can grab a test pitch stick, dip it, let it dry, and test its dry, cooled texture occasionally while adding the scat. It should be firm but not brittle when cool, and smooth, not sticky, yet malleable when warm. Knowing the right texture comes with practice.
5) Pitch glue should be homogenous and very black in color when mixed. When mixed and the texture is to your liking, leave the batch on warm and load up your pitch stick(s)! You can load the ends of the pitch stick by dipping and swirling it around itself as it dries... kind of like wrapping a stick with cotton candy, or a honey stick.
So how do I use this glue?
Great question! You have it stored on your stick to use whenever you need it. To glue, just use a lighter or other flame to melt the glue onto whatever you need gluing! Careful not to melt it onto your skin (kinda hurts) or your lighter (ruins the lighter). Once it's cool enough to touch, but still warm, you can use your fingers to squish it around whatever you are gluing. The end product should be just as strong, if not stronger and more versatile than store-bought glues. There's some examples of projects using pitch glue below!
Written by Chelsea Ernst