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Hafting Adhesives
Asphaltum & Bitumen as Hafting Adhesives
“Bitumen” is a component of crude petroleum - a fossil derived viscous liquid or semi-solid mostly found underlying or soaking through sedimentary rocks or deposits. The precise term would be “crude bitumen”. The term without the word “crude” is used interchangeably with the term “asphalt” (or the more archaic “asphaltum”) in the States. Elsewhere (eg in Europe), the term bitumen is usually reserved for material that has been refined by modern distillation techniques and the term asphalt most usually for man-made road-surfacing material… ie tarmac.
When found naturally as a liquid, heating will drive off the lighter volatile components to leave you with “pitch”. It also occurs naturally in hardened form, having already lost its volatiles. Pitch is a generic term and covers both petroleum-derived material and plant-derived material (resins) with a sufficiently high viscosity that they behave as hard plastic solids at room temperature. That’s what ancient people used as an adhesive cementing (and waterproofing) material – either petroleum or plant derived.
You don’t need too much control to process either of these into a useable form – it can be done on top of a hearth-stone or even on the end of a stick in an open flame, just being careful not to set it alight. Crude bitumen is normally black or very dark brown to start with and lighter colour plant resins will readily carbonize to take on pretty much the same appearance after rendering. You often can’t tell them apart by appearance alone, but analysis of residues suggests that plant pitch was much more widely used than petroleum pitch in North America – except perhaps in specific areas where the latter was geologically abundant. In some cases, archaeologist have been able to narrow the resin down to a specific tree species. The known plant resin pitches used for hafting (as opposed to feather-gluing and other adhesive uses) are:
Sitka Spruce (Picea sitchensis) used by the Hesquiat [Turner & Efrat, 1982] and by the Makah [Gill, 1983]
Twoneedle Pinyon (Pinus edulis) used by the Hualapai [Watahomigie, 1982]
Slash Pine (Pinus elliottii) used by the Seminole [Sturtevant, 1954]
Bishop Pine (Pinus muricata) used by the Kayasha Pomo [Goodrich & Lawson, 1980]
Ponderosa Pine (Pinus ponderosa) used by the Crow and Nez Perce [Hart, 1992] and by the Paiute [Mahar, 1953]
Black Cottonwood (Populus balsamifera) bud-scale resin, use by the Okanagan-Colville [Turner, Bouchard & Kennedy, 1980]
Douglas Fir (Pseudotsuga menziesii) used by the Kashaya Pomo [Lawson, 1980]
As far as glues for hafting is concerned, there was a gradual shift away from pitch adhesives in the archaic period to the use of animal collagen glue in the early historic period. The latter can be derived from the boiling of hide shavings, sinew, hoof, velvet antler and fish skin among others. But it needs the kind of heat control that was only possible after the move from indirect heating with boiling stones to clay pots of good enough quality to withstand direct heating. The switchover broadly corresponds to fire-worthy pots becoming commonplace (post about 700 BC).
Those kinds of residues would be paler in colour (buff through to reddish-brown), but survive only very rarely since they are much more prone to weathering and disintegration from bacterial action.
“Bitumen” is a component of crude petroleum - a fossil derived viscous liquid or semi-solid mostly found underlying or soaking through sedimentary rocks or deposits. The precise term would be “crude bitumen”. The term without the word “crude” is used interchangeably with the term “asphalt” (or the more archaic “asphaltum”) in the States. Elsewhere (eg in Europe), the term bitumen is usually reserved for material that has been refined by modern distillation techniques and the term asphalt most usually for man-made road-surfacing material… ie tarmac.
When found naturally as a liquid, heating will drive off the lighter volatile components to leave you with “pitch”. It also occurs naturally in hardened form, having already lost its volatiles. Pitch is a generic term and covers both petroleum-derived material and plant-derived material (resins) with a sufficiently high viscosity that they behave as hard plastic solids at room temperature. That’s what ancient people used as an adhesive cementing (and waterproofing) material – either petroleum or plant derived.
You don’t need too much control to process either of these into a useable form – it can be done on top of a hearth-stone or even on the end of a stick in an open flame, just being careful not to set it alight. Crude bitumen is normally black or very dark brown to start with and lighter colour plant resins will readily carbonize to take on pretty much the same appearance after rendering. You often can’t tell them apart by appearance alone, but analysis of residues suggests that plant pitch was much more widely used than petroleum pitch in North America – except perhaps in specific areas where the latter was geologically abundant. In some cases, archaeologist have been able to narrow the resin down to a specific tree species. The known plant resin pitches used for hafting (as opposed to feather-gluing and other adhesive uses) are:
Sitka Spruce (Picea sitchensis) used by the Hesquiat [Turner & Efrat, 1982] and by the Makah [Gill, 1983]
Twoneedle Pinyon (Pinus edulis) used by the Hualapai [Watahomigie, 1982]
Slash Pine (Pinus elliottii) used by the Seminole [Sturtevant, 1954]
Bishop Pine (Pinus muricata) used by the Kayasha Pomo [Goodrich & Lawson, 1980]
Ponderosa Pine (Pinus ponderosa) used by the Crow and Nez Perce [Hart, 1992] and by the Paiute [Mahar, 1953]
Black Cottonwood (Populus balsamifera) bud-scale resin, use by the Okanagan-Colville [Turner, Bouchard & Kennedy, 1980]
Douglas Fir (Pseudotsuga menziesii) used by the Kashaya Pomo [Lawson, 1980]
As far as glues for hafting is concerned, there was a gradual shift away from pitch adhesives in the archaic period to the use of animal collagen glue in the early historic period. The latter can be derived from the boiling of hide shavings, sinew, hoof, velvet antler and fish skin among others. But it needs the kind of heat control that was only possible after the move from indirect heating with boiling stones to clay pots of good enough quality to withstand direct heating. The switchover broadly corresponds to fire-worthy pots becoming commonplace (post about 700 BC).
Those kinds of residues would be paler in colour (buff through to reddish-brown), but survive only very rarely since they are much more prone to weathering and disintegration from bacterial action.