TITLE: Workflow for wooden contact samples in use-wear experiments with bronze axe replicas (MAP-protocol_B)
AUTHORS: Ulrich  Thaler, Walter Gneisinger

[DESCRIPTION]
Focussing on the role of contact materials as an element of variable control in archaeological use-wear experiments, this protocol sets out a workflow for the preparation, use and documentation of standardized beechwood contact samples. Although developed in the context of rig-based experimentation with bronze axe replicas as part of MAP, it follows principles and sets out procedures of broader applicability within traceological experimental research in general and in studies involving ligneous contact material in particular.

MAP (the Mainz, Mayen & Monrepos Axperimental Programme) expands into a 'post-lithic' material class (copper-based artefacts) and chronological setting (the Bronze Age) the research agenda developed by TraCEr, which is based on a strong commitment to open science and an understanding of sustained methodological development as a key to consolidating traceology as a sub-discipline within archaeology.

TraCEr (the Laboratory for Traceology and Controlled Experiments) was established by the RGZM, the Leibniz Research Institute for Archaeology, at the MONREPOS Research Centre and Museum at Neuwied in 2017. Its main scope is to carry out ground-breaking research that combines methodological development, aided by state-of-the-art facilities for controlled experimentation and advanced methods of documentation, and fundamental research on Pleistocene and Early Holocene archaeology.

   

[STEPS]
SECTION: Acquisition of contact material
1. Acquisition of contact material

obtain plank of high-quality beechwood (Fagus sylvatica) in a thickness that corresponds to the intended width of your contact samples

  
 

 

 

SECTION: Preparation of contact samples
2. Preparation of contact samples
SECTION: Preparation of contact samples
2.1. Cutting of blanks

cut blanks of the intended size (length and height) of your contact samples from the plank or have them cut

  
  

 

 

SECTION: Preparation of contact samples
2.2. Adaptation to contact sample holder

drill holes through contact samples for mounting on contact sample holder, placing them centrally on longitudinal axis on the top (i.e. the narrowest side)

  distance (of centre of drill-holes from ends of contact sample)
  diameter (of drill-holes / drill-bit)
  depth (of drill-holes, equals height of contact sample)
 
   
 

 

SECTION: Conditioning of contact samples
3. Conditioning of contact samples

bring contact samples to moisture content above fibre saturation point in order to approximate green wood in a controlled manner
 

 

 

 

 

 

SECTION: Conditioning of contact samples
3.1. Priming vacuum pump

after ensuring that the gas ballast valve of the vacuum pump is open and the valve connecting the pump to the vacuum chamber is closed, start the vacuum pump and leave to idle for 20 minutes
20 min 

 

SECTION: Conditioning of contact samples
3.3. Loading vacuum chamber
(can run parallel to 3.1)

stack contact samples in soaking vat in open-pile fashion with stickers, placing weight on top to counteract boyancy, fill vat with (tap) water up to level of weight and place vat in vacuum chamber

   
 
 
SECTION: Conditioning of contact samples
3.2. Weighing contact samples
(can run parallel to 3.1)

weigh contact samples (triple measurement); record result(s) along with the date
 

 

SECTION: Conditioning of contact samples
3.4. Closing vacuum chamber
(can run parallel to 3.1)

once loaded, close vacuum chamber, taking care to only lightly fasten the clamping levers of the door ('finger-tight') and ensuring that the ventilation valve on the door is closed
SECTION: Conditioning of contact samples
3.5. Evacuating chamber

by slowly opening the chamber evacuation valve connecting the pump and vacuum chamber, evacuate the chamber; observe pressure gauge and leave valve open for 1 hour after the reading has stopped falling
60 min 

   
SECTION: Conditioning of contact samples
3.6. Safeguarding against condensation in pump

slowly close the chamber evacuation valve and leave vacuum pump to run on idle for 15 minutes, turning it off only after that time has elapsed
15 min 
 

SECTION: Conditioning of contact samples
3.7. Sorption and absorption

leave the contact samples in the evacuated chamber overnight
  
SECTION: Conditioning of contact samples
3.8. Opening vacuum chamber

open the ventilation valve on the vacuum chamber door, checking that the door clamping levers do not tighten too much while waiting for normal atmospheric pressure to be re-established inside the chamber; once normal pressure is reached, open door
SECTION: Use-wear experimentation
4. Use-wear experiment
SECTION: Use-wear experimentation
4.1. Weighing contact samples and measuring moisture content

weigh contact samples (triple measurement) immediately before experimental use (for the contact sample used first after the opening of the vacuum chamber, a new measurement may not be needed); measure moisture content with hand-held moisture meter (triple measurement in different spots); record results along with the date

 

 

 

SECTION: Conditioning of contact samples
3.9. Weighing contact samples

weigh contact samples (triple measurement); record result(s) along with the date; compare weight to 'target weight'

 

 

 

SECTION: Use-wear experimentation
4.2. Use of sample on contact sample

record sample used on contact sample
 

SECTION: Use-wear experimentation
4.3. Weighing contact samples and measuring moisture content


weigh contact samples (triple measurement) immediately after experimental use; measure moisture content with hand-held moisture meter (triple measurement in different spots); record results

 

 

 

SECTION: Photographic documentation
5. Photographic documentation

 

   
SECTION: Determination of moisture content (oven-drying method)
6. Determination of moisture content (oven-drying method)

determine precise moisture content by oven-drying contact sample until weight constancy is reached, i.e. until weight discrepancy between two measurements at least two hours apart falls below 1‰

 

SECTION: Determination of moisture content (oven-drying method)
6.1. Loading drying oven

place contact samples in drying oven set to 103°C, recording starting date of oven-drying for each

 


SECTION: Determination of moisture content (oven-drying method)
6.2. Oven-drying

leave drying cabinet to run at 103°C on at least 3 to 5 (preferably consecutive) days (period may be shortened in repeat cycles)

 

SECTION: Determination of moisture content (oven-drying method)
6.5. Weighing contact samples and checking weight discrepancy

weigh contact samples (triple measurement); record result(s) along with the date and time for each; compare weight recorded in step 6.3

 

 

 

SECTION: Determination of moisture content (oven-drying method)
6.3. Weighing contact samples

weigh contact samples (triple measurement); record result(s) along with the date and time for each

 

 

SECTION: Determination of moisture content (oven-drying method)
6.7. Weighing contact samples and checking weight discrepancy


weigh contact samples (triple measurement); record result(s) along with the date and time for each; compare weight recorded in step 6.4

 

 

 

SECTION: Determination of moisture content (oven-drying method)
6.4. Waiting period / continued oven-drying

let (a minimum of) two hours elapse before next weight check
120 min 

SECTION: Determination of moisture content (oven-drying method)
6.6. Waiting period / continued oven-drying

let (a minimum of) two hours elapse before next weight check
120 min 
SECTION: Determination of moisture content (oven-drying method)
6.8. Calculation of moisture content

calculate and record the moisture content of the contact sample(s) using the formula

MC = (mwet - mdry)/mdry × 100%

in which mwet is the weight(/mass) recorded in step 4.3 and mdry is the lowest weight(/mass) recorded in steps 6.3, 6.5 and 6.7 (N.B.: not the lowest single measurement, but the lowest weight calculated as the mean of triple measurement)

 

SECTION: Determination of moisture content (oven-drying method)
6.9. Calculation of further attributes

Optionally, further attributes may be calculated at this point.
 

SECTION: Storage
7. Storage

archive contact samples alongside samples

 

  
SECTION: Photographic documentation
5.1. Documentation of full view

take image of full view, including a scale bar, angled to give an idea of the three-dimensional quality of the contact sample
SECTION: Photographic documentation
5.2. Documentation of notch

take detail image of notch as vertical shot, including a scale bar
SECTION: Photographic documentation
5.3. Comparative documentation

Optionally, further images may be taken to directly compare contact samples.