Strong Glue from Birch Bark

Researchers discovered how Neanderthals made a very strong glue from birch bark.

It's a polymer/tar forming process with heat in the absence of oxygen. Some indications of the method are listed in the article. Way cool.

https://arstechnica.com/science/2023/06/neanderthals-seem-to-be-the-first-humans-to-make-synthetic-materials/

Well that would be a project to try

Is someone game to try this?
Questions I have:
1. How specific does the species of tree need to be? I'm not sure we have any "birch" on our land, but just like other plants, there are often close relatives that have similar properties, but sometimes the close relatives lack something that's needed also!
2. How quickly does the "glue" need to be used? There are glues used in the boating industry that are very good, but they have to be mixed, heated and used in a relatively short time-frame and don't leave residue where you don't want it!
3. They refer to it as "synthetic", but then suggest that it is really a simple distillation process - their description sounds *very* similar to the method used to make Sepp Holzer's bone salve for protecting trees. (which I understand is very sticky as well as stinky, but I've not had personal experience with it and I don't know if it hardens or not, or how soon it would do so, or in reaction to what - air, heat, sunlight etc.)

The third method would distill the tar. Because there were no ceramics during the Stone Age, sediment was shaped into upper and lower structures to hold the bark, which was then heated by fire. Distilled tar would slowly drip from the upper structure into the lower one.

4. Another question is whether they type of "coals" put in with the bark made a difference? Was a specific wood burned to the charcoal stage, more of the birch itself, or would any charcoal do?

The article Douglas linked to has a link near the end which might have a bunch more info. They give it a name, "Königsaue birch tar" and those birches would have been growing a *long* time ago, so not only might they have used a specific species, but that species may have changed over the last ... how long ago were the Neanderthals in Europe? I should know, but I'm not good with dates!

I found a simpler method but it does looks it need to be used right after it's made:

Here are the steps on how to make strong glue from birch bark:

- Gather some birch bark. Usual ration is 1 part bark to 5 parts water by weight. You can find birch trees in most temperate forests.
- Peel off a thin layer of the bark. The inner bark is the best part to use for making glue.
- Cut the bark into small pieces.
- Place the bark pieces in a container.
- Add water to the container until the bark pieces are submerged.
- Heat the container over a fire or stovetop.
- Cook the bark pieces for about 30 minutes, or until they have turned a dark brown color.
- Remove the container from the heat and let it cool slightly.
- Strain the liquid through a cheesecloth or coffee filter.
- Your glue is now ready to use!

Here are some tips for making strong birch bark glue:

- Use fresh bark for the best results.
- Make sure the bark pieces are thin and evenly cut.
- Cook the bark pieces for long enough, but not too long, or the glue will be too runny.
- Strain the liquid thoroughly to remove any bark particles.
- Store the glue in an airtight container in a cool, dark place.

Birch bark glue is a natural and sustainable adhesive that can be used for a variety of projects. It is strong, water-resistant, and non-toxic. It can be used to glue wood, leather, and other materials. It can also be used as a sealant or wood preservative.

Here are some examples of how birch bark glue can be used:

- Gluing together pieces of wood to make a small project, such as a birdhouse or a toy.
- Sealing a wooden bowl or other container to make it watertight.
- Preserving a piece of leather to keep it from drying out or cracking.
- Gluing together two pieces of fabric to make a patchwork quilt.
- Repairing a broken piece of pottery.

I will be interested to see people's experiments!

I suspect simple extraction of birch bark resin in water is rather different than "destructive distillation" which is how tars are made from many materials.

I found this quite interesting and instructive:
https://en.wikipedia.org/wiki/Tar

I would guess that Native Americans likely used a version of it to seal their birchbark canoes.

I've made pitch from melting pine resin/sap and mixing it with white wood ash. tough stuff, but can be brittle in the cold.