experiments on possible stone age glue types - openarch conference, kierikki 2014
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Title of the presentation
Experiments on possibleStone Age glue typesWerner PfeiferWerner Pfeifer, Marco ClauenSteinzeitpark DithmarschenAlbersdorf, Germany
Glue types produced:
1. Birch bark tar / pitch2. Pine wood tar / pitch3. Pine resin / bee wax glue4. Pine resin / bee wax / charcoal glue5. Hide glue6. Blue Bell glue
Tar and pitch
is a product of distillation of for example birch bark or pine wood.
Tar is a fluid, watery form, pitch a more solid form of a complex chemical composition, not better defined in my sources.
Tar was mainly used to seal and conserve wood and leather, but also used in medicine, mainly as desinfectant. In North- and East European countries also ingredience of food and cosmetica.
Pitch was mainly used as a glue e.g. in archery and to fill small openings e.g. in ship building.
Open and closed distillation methods used
Open distillation method:
Observations:
1. smoke within 10 minutes
2. first liquid dripping within first 20 minutes
3. after firing 2h, bark had turned into charcoal
4. consumption of a wheel barrow load of wood for each experiment
5. isolation layer sealed very good, except one experiment with higher fine clay content
6. raw clay pot turned into fine ceramic, black colour inside indicating burning without oxygen
Preparing the pipe
Stone support ring
Birch bark pile
Isolation layer
Isolation layersealed
Covered indry grass
Immediately firedfor minimum of2 hours
smoke while firing
gaining liquid and tar
after cooling downsealing layer still intact
charcoal frombirch bark
profile ofsealing layer
Conclusions:
1. method works well2. pitch yield was very low due to low quality of birch bark3. sealing layer consist of high persentage mud and sand,but just little clay works very well, too much clay results in cracks4. Sealing layer burns into soft, brittle sherds, dissolves quickly,no traces for archaeologists after several years5. No visible traces of tar in sand only experiment.6. Consumption of large amount of wood suggest prehistoric distilleries to bein former woods, not in settlements.7. Clay pot turned black inside without visible traces of tar.Thus look for these sherds and do chemical and microscopic investigationsinside the sherds when searching for Stone Age tar distillation indications.
Closed distillation methodby Marco Clauen
Observations:
1. Although most heat of the fire is going upwards, most birch bark in the pitsturned into charcoal, specially in the upper parts.
2. The yield of liquid and tar seemed to be slightly more than in the open distillingmethod.
3. It needed about the same amount of fire wood as above experiments.
4. One experiment with a 60cm deep pit failed to produce enough heat,due to reduced oxygen in the pit.
5. One experiment with building a heap over a pile of bark failed, due too thickisolation layer (8 10cm).
The pit
The skull vessel
The clay bottom
Pilar stones
Deck stoneabove vessel
Marco and hispit
Birch bark added
Filling gaps withgrass and twigs
Covering allwith grass
A layer of soilon top
Firing for2 3 hours
Let it cool down forminimum one hour
Opening itcarefully
Grass turned tocoal
It's still hot, seesmoke
Most birch barkturned to coal, lowerparts not
After removingdeck stone:
Tar inside skull,plus outside, dueto skew placementof skull
Tar in clay pit didnot enter the clayand was scoopedout later
Conclusions:
1. This method works very well.
2. As wood consumption is very high, I expect the Stone Age distilleries to be informer woods, not in settlement.
3. As the fire needs a lot of oxygen to reach high temperatures, deep pits areno good. Fires on or above ground level work well.
4. The isolation layer between fire and birch bark must be thin. More than 4 cm ofsoil seems to be too thick for the heat to enter the inner properly.
5. The remains of this distillation process leaves no long term visible traces otherthan of a normal camp fire.
Turning tar to pitch
Heating it carefully
Skull works very well
Future heatingexperiments plannedwithbirch bark container,hooves and horn,and wooden bowls
Pine wood tar and pitch
Aim: producing pine pitch to compare it with birch bark pitch
1. open distillation method (with metal container)
2. finger thick pine wood was used
3. wood turned into charcoal, used later for heating tar to pitch
4. pine pitch looks alike birch bark pitch, smells different
5. future experiments need to compare glueing abilities
Pine tar and liquidafter distillation
Pine wood distillation
after firing for 2 hours
Pine resin / bee wax glue
Pine resin becomes brittle after a while, thus is no good glue in it selv.
Mixing about 3 parts of pine resin with one part of bee wax gives, after meltingall together, a very fine glue.
The bee wax keeps it smooth, althoug the glue is very strong.
I received the recipy from Robert Berg (Thunderbird Atlatl, USA). He uses thisglue on his spear tips while hunting wild boar with Atlatl.
I use it on flint knife, arrow- and spear tips too.
As it is very quick and easy to make, I can imagine that it might have been used in Stone Age, specially when compared with the effort of making pitch!
Pine resin /bee waxglue
on arrow heads
Pine resin / bee wax / charcoal glue
Mixing above components 3:1:1 gives a very hard and strong glue
I got the recipy from Ben McNut (Woodsmoke bushcraft company, UK) and hadtested it several years ago on arrow heads. It's a very good glue.
As it is black in colour, it might easily be mistaken for birch bark pitchin archaeological contexts, just by the look at it.
As it is very easy to make, much more easy than distilling tar / pitch, I couldimagine, that it had been used in Stone Age very well.
Hide glue
Hide glue and bone glue was used until very recently a lot in binding wood, horn andhide onto each other. Friends of mine use it in making traditional Asian composit bowsor glueing reptile or fish hides on the back of a bow.
I made two experiments by boiling hides in water:
1. Pig hide is too fatty and did not melt.
2. Cow hide turned into good glue.
As hide or bone glue is effected negatively by moist weather, if not sealed, it mighthave not been used in Western Europe during Stone Age, but in dryer areas it mighthave, as it is made easily and the raw material was always available.
Cow hide glue(left)
Pig hide too fatty to melt(right)
Blue Bell glue
The Blue Bell (Hyacinthoides non scripta) grows in some areas in Western Europe.The underground onion produces a sticky, clear glue when squeezed. According to BenMcNut (Woodsmoke bushcraft company, UK) it was used in formertimes in Brittain to fletch feathers on arrow shafts.
It thus might have been used in Stone Age too. Unfortunately due to it's organic nature,it will not appear in archaeological records.
I still need to test in on arrows.
Hyacinthoides non scripta
Blue Bell
Hyacinthoides non scripta Blue Bell
Onion of theBlue Bellwhen squeezed
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