Table 4 Summary of techniques discussed for the assessment of the relative amounts of wood components

Gravimetric analysis (Acid insoluble lignin/TAPPI methods)

Relative composition by mass of extractives, carbohydrates and lignin in wood; ash content by combustion usually carried out alongside

Numerical values allow comparison; well-established technique; cheap; more detail than loss of wood substance

Time consuming; large degree of error; potentially dangerous chemicals; too harsh for heavily degraded samples

Dry sample (not conserved); destructive; > 1 g recommended (larger amount reduces error)

Combustion analysis (CHN(S))

Relative composition by mass of CHN (and S in some cases)

Straightforward data interpretation; readily available

No structural information; oxygen content not directly analysed; determination of relative amounts only; heavily influenced by conservation agents and wood species

Dry or conserved* sample; destructive; approx. 2 mg sample required

Thermogravimetry

Relative composition by mass of water, cellulose, lignin and ash

Small sample size; relatively fast (compared to extraction)

Less familiar than many techniques; requires specialist equipment; lignin content can be very difficult to determine in archaeological samples

Dry or conserved* sample; destructive; approx. 5 mg sample required

Specialist instrumentation (FTIR, Raman, Py-GC, NMR)

Relative composition of celluloses and lignin (L:C ratios)

Simultaneous analysis of molecular changes; small sample sizes; fast analysis (compared to gravimetry)

Requires specialist instrumentation; cannot accurately assess ash and water content

See individual entries in Table 6