Once out of the pot we could see that the tree had very good fibrous roots, some of the Akadama compost material had broken down a bit to form more of a mash than graduals.

Using a root hook the existing Akadama compost mix was carefully teased out of the root ball, this can be a time consuming business but should be done thoroughly, particularly under the base of the tree. It is important also to spray the root ball with water regularly to make sure that the root ball does not dry out while this process is being done.
All the hanging roots to the base of the root ball were pruned back together with some light trimming of the perimeter roots.

With the existing compost removed and the root ball trimmed down, now it was time to get the tree back into a bonsai pot. The existing blue oval pot that the tree had be planted in in Japan looked OK but it had some damage to the rim at the back of the pot and the drainage holes were very small and not very numerous given the size of the pot.
Our host Dan Barton had quite a selection of pots on hand to choose from, so the hunt was on for a suitable new pot for the tree. We tried a lovely pale blue oval which was much bigger than the original pot both in length and front to back dimensions, but we felt that it was just too deep in it's front to back dimension.

The pot was prepared by wiring in plastic mesh over the drainage holes, which are much larger than those of the original pot, and a tie wire under the base of the pot coming up through two drainage holes to tie the root ball down at the back of the tree.
A drainage layer of large sieved Akadama mixed with Kiryu was used to the base of the pot followed potting the tree up in a compost mix comprising of 4 parts medium sieved Akadama to 2 parts Kiryu. During the re-potting we also took the opportunity of thinning out the Japanese ferns that were growing in front of the rock.