Birch Tar that didn't set hard

[jon r]

I made some birch tar about a year ago and it's still not set It should set in mins not years!

Why could this be?

I want to make some more soon and dont want the same think to happen again so is there anything i could have possibly done wrong?

Jon

[Draven]

Could there be other oils in with the tar which are causing it to stay "gooey"?

[bambodoggy]

I didn't think birch oil was supposed to set hard.....I could be wrong but I'd never have expected it too.

Cheers,

Bam.

[jon r]

I think the birch bark i used last time was fresh straight from a living tree which had just been cut down. Maybe there was lots of other sap in the bark which stopped it from setting.

[Hartung]

Jon,

if you made your birch bark tar my dry distillation it will “never” „set“ by it’s own. You have to simmer (no boiling, attention, this is a very dangerous procedure!!!) for many and many an hour until it becomes very thick …..

[jon r]

dry distilation? please explain more. And why is it dangerous to boil?

Many thanks

jon

[bambodoggy]

I think by dry distillation he means that you heated the bark until the oil was released....sort of baked it with an escape hole for the oil to drain from and something for it to drain into. What you did basically speaking was producing birch oil by dry distilation although it isn't really distillation if that makes sence?

As for it being danerous to boil it....It's a bit like simmering birch or maple sap down to make it thicker and into syrup but because you are doing it with oil you stand a very fair chance of the almost boiling (simmering) oil bursting into flames and the very last thing you want is to spill any of the hot oil on the fire!!!!!

If you just simmer it and simmer it then it should eventually thicken up and when it's thick enough it should set hard when cooled.

Hope that helps,

Bam.

[Hartung]

Excellent explanation Bam :-)!

[jon r]

Thanks for the info! Are there other ways to collect birch tar which allow it to set straight away when cooled?

[Hartung]

Freeze it…..:-) just kidding. It will never set just by letting it “dry”. The only way for it to „set“ is to simmer it until it becomes “hard” when cooled down. For applying the tar, reheat small quantities and apply hot, than let it cool down – in fact it will cool down / tighten very very fast (almost as fast as cyanoacrylate) and you have to be quite fast applying it / working with it.

Manufacturing birch bark tar is quite an art as well as a tremendous amount of work. In fact I’ve never ever seen real birch bark tar elsewhere than in very small quantities made by friends. The pitch that is sold as birch bark tar is very often nothing else than pitch made from cork oak [Quercus suber].

To my opinion, real birch bark tar, if not made in industrial quantities would be very expensive (more expensive than epoxy) regarding the labour involved in the manufacturing process.

Any other opinions?

[bambodoggy]

Thanks for the info! Are there other ways to collect birch tar which allow it to set straight away when cooled?

Not that I'm aware of Jon, however, I'm hardly a world expert! lol

[Voivode]

Thanks for the info! Are there other ways to collect birch tar which allow it to set straight away when cooled?

From a chemist's perspective, it sounds like there are other volatile oils mixed in with the bit you want, preventing it from "setting", as you call it. There are two basic ways to purify things; distillation and solvent extraction. Boiling off the volatile bits is distillation without capturing the volatile fraction, reserving only the stuff that boils at higher temperatures.

Solvent extraction doesn't require the boiling and can take relatively little time, but you would have to know what solvents to use to separate the bits you want from the bits you don't. This really only works well when you're trying to produce a pure fraction of a particular chemical; I'm certain your birch tar, even when 'purified', is still a mixture of a whole variety of compounds. That complicates matters greatly and really puts the whole technique back into the lab, unless you've got a whole bunch of raw material and a variety of solvents to play with.

On the whole, boiling it down is probably the answer, as time consuming and challenging as it is. Sorry.

[jon r]

I think i will just stick with the boiling process

Voivode, Hartung and Bambologgy, you sure know your stuf when it comes down to birch tar!!

Thanks guys

Jon

[Hartung]

Jon,

just to water your mouth …. :-)

Pure Birch bark tar, hard, not flexible, you can’t push your thumb into it.
Pure tar

Birch bark tar with ashes, hard like hard rubber, difficult to push your thumb into it but “flexible”. This one is dull but will become as brilliant as pure birch bark tar once reheated.
Tar with ashes

[Toddy]

Nice stuff Hartung

Jon r you haven't said what you were thinking of using the tar for. It's usual to mix it with fine charcoal if it's to be used like a glue since this helps to stop it shattering. It is an excellent material with a very long history. Boiling it is always a pain since the fumes it gives off are flammable.
If you intend to use it in soaps and the like please be aware that it is considered carcinogenic. I can provide the links if you need them.

cheers,
Toddy

[jon r]

I was just planning to use it for spears and maybe arrows and things like that.

[Pipistrelle]

Mix in some hot pine resin (remove all the impurities first), hey presto setting tar and boy is it strong, but takes a while to collect enoufgh resin.

[jon r]

Mix in some hot pine resin (remove all the impurities first), hey presto setting tar and boy is it strong, but takes a while to collect enoufgh resin.

sounds like a good idea. Ive used pine resin before but there are usually a lot of impurities. Is there an easy way to remove all the bits of wood, bark, chaf etc?

Maybe a metal sive would work well if it didnt set too fast. What are your thoughts?

Jon

[Voivode]

sounds like a good idea. Ive used pine resin before but there are usually a lot of impurities. Is there an easy way to remove all the bits of wood, bark, chaf etc?

Maybe a metal sive would work well if it didnt set too fast. What are your thoughts?

Jon

You can filter most anything if you can keep it liquid long enough, which can be a trick with stuff like natural resins and tars. I might suggest trying to get your pine resin nice and liquid and keeping it hot enough that it is liquid but not boiling. The sediments should settle to the bottom of your pan, allowing you to decant off the good stuff. You might also be able to filter it through a metallic strainer or seive, perhaps lined with cheesecloth? You'll need to be working with a good amount because you'll lose some in the process.

I don't actually know all that much about birch tar per se; I did a chemistry degree so am approaching it from a scientific angle.

[Biddlesby]

Made a bit of birch tar too. If you want to make glue, is mixing with charcoal enough or do you have to boil it [i]as well[i]?

[Hartung]

Some interesting points have been raised yesterday that I’d like to comment one by one.

Pipistrelle:

You suggest to mix “some hot pine resin” into the birch bark tar. How much is “some”. Could you give any, even approximate, percentage tar/resin? I would be grateful too if you could give us some more details concerning your experience with that mixture.

I once accidentally mixed “some pine resin to birch bark tar. I didn’t experiment with that mixture but here is a pic of it. After cooling down, the surface had lots of small crater like holes. Did your mixture had the same holes?

[IMG][/IMG]

[Hartung]

Jon:
You asked how to filter the pine resin. You need two pots, one metal sive with very small holes, a scoop and a spoon.

First heat some of the resin in one pot. Two to three minutes before filtering the resin put the second pot on the “fire” and the metal sive on top of it. That will heat both of them sufficiently for the filtering procedure because the sive has to be hot or the resin will occlude the sive.

Than take the scoop and slowly pour the resin in the sive. It may be that the resin passes very slowly. You can than take a spoon and push the resin through the sive. That should work quite well. The heat that comes from beneath the sive will keep it hot so that the resin will continue to pass through it.

Every now and than remove the impurities from the sive.

How to do it:
[IMG][/IMG]

Resulting pine resin:
[IMG][/IMG]

[Hartung]

Toddy:

Thanks for your nice comment. You say “It's usual to mix it [birch bark tar] with fine charcoal if it's to be used like a glue since this helps to stop it shattering.”

That is the first time that I hear someone taking about adding charcoal (powder/dust). I always heard that the birch bark tar should or could be mixed with “some” of the remaining birch bark ashes.

It is true however that the “Indians” used charcoal powder dust and added it into their pine resin-fat mixture they used to water tighten the seams of their birch bark canoes. Last year there was I time when I really did not understand how the charcoal powder would prevent the seal from shattering/breaking. So I asked someone who builds birch bark canoes for a living and he told me that the only reason why some people would add the charcoal powder is to hide “badly worked seams”. He does not add charcoal powder to the resin.

I did a small trail with adding charcoal powder to the resine and left it for more than one year but I would not say that it prevents the resin from shattering.

I also added birch bark ashes to my birch bark tar and would not say that it has a noticeably impact on the tars ability not to shatter. Its capacity not to shatter, to my opinion, is much more a question of how long you simmer it than of how much ashes you add to it.

Of course I did not add charcoal powder to my tar but birch bark ashes which are by far not as fine a dust as the charcoal. That might make a difference but I’m in doubt.

I do hope you could add more to this subject.

Left birch bark ashes, right charcoal powder dust.

[IMG][/IMG]