On the Doctrine of (vape) Signatures
In the beginning, vaping devices had a signature design or signature materials, producing signature clouds or a signature taste or aroma, especially from oven materials or different woods. And the signature effects of different strains were known and ascribed to their spectrum of active compounds.
Vape signature was coined by stickstones in 2013, and related to "each vape's unique combination of heating methods (conduction, convection, radiation) and the timing of the heat". Just as tolerance to different strains develops, a tolerance to particular devices is noticed, with signature tolerance corrected by a signature change to a different device. And signature change might explain the euphoria and honeymoon period of a new device.
The idea of signatures soon took flight, with strain signature, temperature signature and vape signature all contributing to signature effects. Although sometimes signature is referring to the taste and sometimes to the effect, and any distinction is not always clear. And without some science the assessment of signature is subjective, but with experience distinctive sensations and correlations are certainly recognised.
Different strains have different amounts of active compounds, and higher temperatures extract a greater range of those chemicals. And vape signature and signature tolerance are similarly related to the proportions of active ingredients in the extract or the amounts effectively absorbed.
In general, indica strains, higher temperatures and conduction heating have a more heavy, body effect, while sativa strains, lower temperatures and convection heating have a lighter, more heady effect. And while the different effects are due to the various compounds in the extraction, the interaction of different cannabinoids and synergy of cannabinoids and terpenoids leads to a complex entourage effect and proportions can be more important than sheer amounts in the final effects of the vapour.
Another approach suggests that the size of the vapour droplets can explain the vape signature, with larger droplets more likely to settle in the oral cavity for more flavour and smaller droplets penetrating more deeply in the lungs for greater absorption and more effect. A lower pressure can generate finer particles and this principle is applied in some vapes, and tamping the herb or adjusting the airflow can affect the apparent signature. Details of geometry, flow paths and turbulence contribute to the quality of the vapour produced, and both pressure and effective temperature at the point of extraction can be varied by draw strength etc. so technique plays an important role.
Vape signature is generally equated with conduction/convection, and if convection and conduction in themselves create different feelings then each process must be delivering the available compounds in different amounts. Convection preserves more flavour through to higher temperatures, and conduction could lose some volatile ingredients by longer heating, so perhaps that makes the difference.
The particular herb and extraction temperature have the greatest influence on effects. And when riding the line and extracting everything available to the verge of combustion, a full extraction from similar material should have the same active compounds, except for the variables of what might be lost (escaped from the oven or trapped by the device) or degraded (such as THC to CBN). Along with variations in absorption from different sized droplets and the distribution of ingredients in those particles, such factors could cause subtle changes in the final effect.
The signature of convection is perhaps due to less degradation of THC, more terpenes or larger droplets, and the signature of conduction to more degradation, less terpenes or smaller droplets, but temperature and technique are probably more important in the particular effects obtained from a device.
If a vape is continuously used in the same way with similar herb then that consistent signature can induce a tolerance, and a signature change can provide a stronger effect. But the effective vape signature is a complex equation and the definition of a device's intrinsic signature based on distinctions such as heady or body stone is difficult, and further complicated by individual tolerance and physiology.