Roman Super Glue

[griffin]

Similar article in English:

http://news.scotsman.com/international. ... 1896952007

[Doc]

Well cattle fat is no problem.

Bitumen supposedly should be like asphalt or tar. However, from what I understand, Bitumen has a different chemical composition than the other two. Using asphalt or tar may not yield the same result not to mention that if it is stronger than we have not concluded anything.

Bark pitch? Does it mean sap? If so I think we can find some of that.

I think that the cow fat (I am only speculating here) works as the "solvent" to allow the components to mix. Sap as we know is very sticky and so is asphalt. Also when sap or asphalt dry out, they are quite hard and bind very strongly to what they are adsorbed on (it is not a typo since adsorption and absorption are completely different).

So the fat is a mixing medium and the other two are binders that act cohesively. The reason I am making the statment that the fat is a mixing medium is because bitumen and sap are not readily mixable unless heated appreciably. Fat on the other hand when heated can melt into a liquid and cause the other two to just dissolve (like sugar in water). This keeps manufacture simple because a liquid solution viscous or not can be spread easily by brush or cloth. This is possible because bitumen, sap, and the cattle fat are mostly if not all organic substances.

So having a vat of this stuff warm or hot (depending on the melting point of the substances involved especially the sap and cattle fat which can decompose into a tarry subsatnce if overheated) available for spreading would be excellent for quick and easy repairs.

I doubt you would get the same result with water as the dissolving medium.

Paolo

Paolo

[Gaius Julius Caesar]

Bitumen was stil lused to coat piplines in the early seventies to stop them rusting, I wonder if it is still available.. :? roll:

[Matt Lukes]

It certainly does sound like the kind of thing you'd fill a repousse piece with to protect it from being dented as opposed to strictly an adhesive- and that itself would need adhesive properties to be effective...

[Caratacus]

People have been using 'animal' glues for centuries. Things such as hooves and horn have formed the basis of most woodworking glues until the advent of the modern pva type of polymer.

I think that Doc is right. We recently used beef tallow at the Museum in Caerleon to try and make some tallow candles for a project on Roman lighting. It melts down very easily and remains liquid for quite a long period, before suddenly starting to set. We found that it penetrated the (unglazed) flower pot that we were using as a melting vessel quite a long way (we dropped the thing eventually, that's how we found this out).

Fats are esters, compounds of long-chain fatty acids and alcohols like glycerol (yes, I'm an organic chemist as well). They are therefore hydrophobic, but oleophilic (oil-liking, water-hating). A substance such as bitumen will also be largely made up of molecules with long chains of carbon atoms and these would be chemically very similar to the fats and would probably dissolve reasonably well in such a solvent.

The success of a glue lies in being able to penetrate to some degree the two surfaces to be joined. This provides a 'key' to link the two surfaces together. To do this, the solvent has to have a fairly low surface tension so that it can be drawn into the surface cracks, etc. by capilliary action. I would guess that something like liquid tallow would be able to do this quite well - it certainly penetrated our flower pot! :lol:

[Doc]

Caratacus,

Good old triglycerides. I think that heating the Bitumen and pitch bark would require a higher temperature. I am not sure however as to their melting points. However, taking an organic like ptich bark and trying to melt it may cause decomposition. Asphalt/Bitumen won't really decompose futher but have a high melting point. So to me the only logical deduction was to use the fat as the solvent.

The reduced hydrogen bonding does have an effect on lowering the surface tension (unlike water). However, the long chains on the fatty acid esters do have strong London and or Dispersive forces due to the large instantaneous dipole moments imparted by the large number of carbons. This still makes them have some appreciable viscosity and will not be that fluid.

I cannot find cattle tallow so I think I will use lard (pig fat). I am not sure how different this will be. Maybe any saturated animal fat would work equally well. I will also use asphalt since bitumen is not easy to come by.

The only problem I am having is using this pitch bark. I was thinking of using maple syrup since I read that pitch bark is like sap. Well maple syrup is maple sap. Outside of this, I would have to grind some bark pieces from a tree, use a soxslet extractor with either methanol or ethanol solvent followed by methylene chloride to assure complete extraction. This solution I would rotary evaporate and remove the solvent.

I have to see. Let me know what you think

Paolo

[caiusbeerquitius]

Pitch and sap are quite different. Read:

J. M. Grünberg: Middle Palaeolthic birch-bark pitch, in: Antiquity 76, 2002, 15-16.

J. Koller, Ursula Baumer, Dietrich Mania: High-Tech in the Middle Palaeolithic: Neandertal-Manufactured Pitch Identified, in: European Journal of Archaeology 4, 2001, 385-397.

J. Weiner: Praktische Versuche zur Herstellung und Verwendung von Birkenpech, in: Archäologisches Korrespondenzblatt 18, 1988, 329-334.

J. Weiner: European Pre- and Protohistoric Tar and Pitch: A Contribution to the History of Research 1720-1999. Acta Archaeometrica 1, 1999, 1-109. (Coburg).

P. P. Anthony Mazza, F. Martini, B. Sala et. al.: A new Palaeolithic discovery: Tar-hafted stone tools in a European Mid-Pleistocene bone-bearing bed, in: Journal of Archaeological Science 33/9, 2006, 1310-1318.

See also:
[url:1e1v5a76]http://en.wikipedia.org/wiki/Pitch_%28resin%29[/url]
Note that Tar and Pitch is the same thing.

[Caratacus]

Doc:

We bought the beef tallow (we also tried pig) from a supplier that specialises in goods for people who make their own candles. The stuff we used was purified, so it didn't stink (too much) when we set it alight. I would imagine that you could do the same in the US?

I don't know off-hand what the length of the carbon chains in these animal fat molecules is. Stearic acid has (I think) 17 carbons (not animal, I know). Certainly the viscosity was very low once we got the tallow melted and heated up. The odd thing we found (by trial and error) is that in order to make the candles, you had to dip the wick in when the tallow was fairly close to the melting point - otherwise it was just melted off as soon as you dipped the wick in! Not that this has anything to do with our problem here -interesting though!

The only thing that bothers me wrt your proposed extraction method is that it's a bit high-tech! Can't see them Romans using a Soxslet extractor, somehow.

The use of maple syrup is intrigueing me. I presume that it is a glucose/fructose mixture as it's liquid, rather than sucrose? Lots of intermolecular hydrogen bonding going on there potentially. I wonder what the high temperature would do to this? Dehydration with the formation of double bonds, possibly. It strikes me that this whole exercise is a good subject for someone to do a Ph.D. on. :lol:

Good luck with the experiment - fascinating stuff!

[Hibernicus]

Pitch? ....try searching for "rosin".

[Hibernicus]

MODERN USE: cow tallow used with asphalt

http://www.oregonlive.com/special/madco ... 4_one.html

[Hibernicus]

beef tallow.. one USA source..

http://www.welch-holme-clark.com/edible ... _spec.html

[Hibernicus]

more glue

http://www.blackwell-synergy.com/doi/ab ... .tb01025.x

[Wes]

I just got a catalog in the mail that sells Powdered Hide glue

$2.00 per Ounce

or

$21.00 per Pound

Leather Unlimited is the name.

www.leatherunltd.com

[Doc]

Caratacus,

I guess that is why it is reasonable to assume that the fat is the solvent so that there would not be the need for high temperature reactions and dissolutions.

Also I know that the romans did not have a soxlet extractor but in the interest of trying it out ourselves, I think it would do nicely.

The romans could have easily taken the bark, ground it and dissolve it in vinegar since it contains acetic acid. The vinegar soltuion could have been easily brought to a boil to maximize extraction. Hopefully, it would have not been too acidic causing any hydrolysis.

They could have then evaporated the soltuion to dryness.
(Imagine the incredible pungent smell of the acetic acid vapors; enough to clear out all the sinuses).

Paolo

[Gaius Julius Caesar]

I'm sure that wouldn't put them off LOL, after all, the did collect urine in pots for commercial use hock: bleackk