Step by step bucket flotation: 
Portable Archaeobotany

An archaeobotanical flotation photo gallery

This page provides step-by-step instructions for bucket flotation of wash-over type. Watch a YouTube video to see how it is done: Portable Archaeobotany 1.

 

  • 1. the sample (or part of it, usually 3-5 litres of sediment) is place in a bucket, water is added, and it is stirred up by hand and clods are gently broken down manually.
  • 2. The water is then further stirred and poured over the lip of the bucket into a receiving sieve (often 0.5mm, although 0.25mm may sometimes be preferred) where the flot is caught. Sand and the heavy fraction remain in the bucket.
  • 3. Water is re-added to the bucket and the sediment is stirred again and step 2 is repeated. This should be down at least 3 times.
  • 4. water is added, but this time it is not stirred is the hands, only the rocking of the bucket is 
  • 5. The heavy fraction that remains in the bucket can then be emptied onto a coarser metal sieve (of 1mm or 2mm) and is then wet sieved for bones or artefacts. This whole process is repeated again with further sediment until the entire sample has been processed. 
  • 6. When all of the sample has been floated, the sieve should be left to dry, preferably in protected from direct bright sunlight as rapid drying may lead to the cracking of charred seeds and charcoal fragments. Preparation of cloth sieve-bag is recommended as it saves time in cleaning out sieves, and allows samples to dry more easily. This bags consist of a graded nylon mesh (e.g. of 0.5 mm or 0.25 mm) cut into a square (approximately 30cm or 1-foot, and then sewn into the bottom of a square bag: thick of it as a 1-foot cube, with sieve on one side and opening on the other.

 

 

 

For another description of bucket flotation, of tea-strainer type, (with images), see that of Cheryl Ward, an archaeobotanist in Florida: here