Recipe for birch bark tar?

[Hartung]

Hi friends,

I’ve got a specific question concerning birch bark tar used as an adhesive (arrow fletching and hafting points).

I’ve already produced quite a lot of “pur” birch bark tar as a result of dry distilling birch bark and thicken it in.

In the pic on the left you can see the gum like tar, on the right side you have some tar after long time simmering; the last one is hard. The problem is that the hard one is too brittle.

Now, I know that I should add some charcoal powder to the gum like tar which should give a hard and non brittle adhesive. Does anybody happen to have a good working recipe (exact quantities) for that mixture birch bark tar/charcoal powder?

Any help is appreciated! Thanks!

 

[Tor helge]

I`ve actually never heard that people in Norway used birch tar as glue.
But I`ve heard of heating/burning birch bark and chewing it to make a sticky substance, and then use it as glue. I`m uncertain of the details (how much they heat it and so on)

Tor

 

[torjusg]

We did, Tor Helge, at least in the stone age.

Interesting procedure you mention as it may work without a tin can. From what I understand, one of the great mysteries in stone age technology is that noone knows how to make birch tar without metal.

Torjus Gaaren

 

[Hartung]

Torjusg,

I remember having read two recites about making birch bark tar without metal containers. The first one within a pot of clay the other one letting the tar drip in a hole in the ground ... but don’t remember the source.

The problem is that there are some description of how making birch bark tar...that is the distilling of it which, in fact, is not too difficult if you have gathered some experience. But I’ve not yet found a good description of how to use it as an adhesive. The craftsman I know off using it for their fletching won’t give their knowledge away

I could of course make my own trials. I just don’t want to waste the tar I have for such a kind of experience. So I first would try it by asking .... I’m however afraid that I won’t have a choice ... I’ll perhaps have to make the experience on my own.

 

[torjusg]

Hartung,
Cheap fella that craftsman.

There was an article in issue 29 of the "Bulletin of Primitive Technology" about birch tar. Quite extensive one too, it contains a recipe. Rather long, but I will read it through again and try to sum it up for you.

Torjus Gaaren

 

[Hartung]

Torjusg

That’s very kind of you. I already know how to make the tar. What I’m interested in is just the very last steps of producing the adhesive. That means do they cut the tar with any additional substances such as charcoal powder / Birch bark coal powder and if so: how much of that substances (percentage) for how much tar?

I’ve heard from several sources that the tar has to be mixed with that kind of substances. Otherwise it’ll be either to soft or to brittle. What I have heard so far is that the powder seems to act as a kind of “binder” like in epoxy glue.

Thanks!

 

[torjusg]

The author claims that the birch tar can be used without binding as it is.

He names possible errors and this one may apply to your case:

Cooking it too long leaves it brittle. The case at right in your picture.

It should be sticky and adhere to things when hot, no mixing is needed at all. Smear it on and it should work.

Please tell us if you get it right.

Torjus Gaaren