Comparing different pre-treatment methods for strongly compacted organic sediments prior to wet-sieving : a case study on Roman waterlogged deposits

Four pre-treatment methods have been tested on strongly compacted organic sediments prior to sieving. They comprise of heating, freezing, soaking in NaHCO3 (sodium bicarbonate) and heating with 10% KOH (potassium hydroxide). The aim of the experiment was to find out which pre-treatment method facilitates the sieving process without destroying the waterlogged plant remains recovered. Several methods are already described in the literature, but only few systematic comparisons of pre-treatment methods were undertaken. Of the four techniques tested, freezing the samples prior to sieving came out as the best option; it eases sieving and has the least damaging impact on the waterlogged plant remains. In addition, it is fast, uncomplicated and does not leave any chemical waste.