1. Intangible archaeologies of hot air
MONSOON STEEL
Intangible archaeologies of hot air

5. Sri Lanka

6. Samanalawewa

7. Archaeological survey and excavation over a number of years revealed a major industry (80+ sites) of the 7th and 11th centuries AD, based on a wind-powered linear furnace design

8. Reconstructed furnace from archaeological evidence

9. Experimental smelts in 1994 and 2007

10. mid-smelt
towards end of smelt

12. Flow of air and flame up the front wall - 2007

13. Smelting at night

14. Smelting at night gave clues to the complex air flows
through and over the furnace

15. Breaking apart the
furnace and slag
to retrieve the
metal ‘blooms’

16. Metal products of smelts
Analysis showed this to be
high quality high-carbon steel

17. High-carbon steels and Damascus swords
At the time the wind-powered furnaces of Sri Lanka were producing
high-carbon steel the Early Islamic
writer al-Kindi praised Sarandibi
steel as one of the most desirable
for sword-making

18. Data visualisation
Data sets
wind direction and velocity for region and macro-environment
wind direction and velocity for site-level environment
wind velocities at furnace level during experimental smelting
furnace temperatures at tuyere (air inlet) and charcoal bed during smelting
ore and charcoal fuel charging weights and rates
tap slag running times

19. Tangible and Intangible Archaeology
The results of the field experiments were published in Nature (379, 1996)
Tangible and Intangible Archaeology
Collected hard evidence – slag waste, metals, furnace remains, experimental experience, images, data
How do we ‘capture’ the fugitive but critical evidence of natural and managed air flow and combustion?
How do we visualise it and importantly use it as a tool for further research?

20. First interpretation of air flow through furnace based on observations and recorded data (furnace cross-section)

21. Further research using computational
fluid dynamics (CFD) at Exeter refined
the initial analysis. Paper with Gavin Tabor published in Journal of Archaeological Science

26. Arrangement of instruments to measure temperature

28. Computation of all temperature readings across furnace through duration of smelt (Matt Baker)

29. Further applications: other furnace technologies
Sri Lanka: small, bellows-driven shaft furnace last used in early 20th century
Well-recorded example with archaeological, ethnographic and documentary records

30. Furnace shape and size reconstructed from excavation and written accounts
Experimental example built and run in Exeter by engineering students (MJ Baker, R De Salis, D Dawson)
CFD analysis of airflows including quasi-sinusoidal flow model

33. POTENTIAL
With good datasets from archaeological excavations and experimental smelting
Visualise and model CFD data
Potential as a tool for study and interpretation of ancient pyrotechnologies
Potential to make visible intangible archaeology
Potential for interdisciplinary knowledge transfer and public dissemination
Potential to engage with creative industry to present science and technology
THANK YOU