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Wood-Tar Pitch: Tar Boiled Down (Ure, 1839)
Pitch is tar with its volatile part boiled away. Ure (1839): boil tar in an open iron pot until the volatile matters are driven off. What is left is brittle when cold and soft when warm, the binder for a chaser's pitch bowl. Boil birch tar outdoors over a gentle fire, test a drop on a cold stone, and pour it out to set.
The picture: our diagram of the pot and the drop test.
Beginner
A few hours
Instructions
1
1
Heat the tar outdoors
Heat the tar outdoors
Weigh birch tar into an open iron pot and set it over a gentle fire outdoors, away from buildings. Keep a lid at hand to smother a flare-up.
Materials for this step:
Birch Tar1 kgTools needed:
Cast Iron Pot
Fire Pit
Digital Kitchen Scale
Leather Work Gloves2
2
Boil it down
Boil it down
Boil it gently, stirring, until the volatile part has been driven off.
Tools needed:
Cast Iron Pot
Wooden Stirring PaddleLeather Work Gloves3
3
Test a drop
Test a drop
Drop a little on a cold stone. When the cooled drop is brittle and snaps, the pitch is done; if it stays soft, boil longer.
Tools needed:
Flat Stone SlabWooden Stirring Paddle4
4
Pour and keep
Pour and keep
Pour the pitch onto a wet stone slab to set and weigh it. It softens again with heat.
Tools needed:
Flat Stone Slab
WaterDigital Kitchen ScaleLeather Work Gloves5
5
How much boils off
How much boils off
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