A Weekend at the Beach

We have been lucky to have been invited to spend a weekend at the beach with our friends Toni and Chris. We have been there twice before. On each occasion we collected pumice off the beach as well as cuttle fish bones. We mix these two materials together to make a green stoneware glaze that is reminiscent of a Northern Song Dynasty, Chinese inspired celadon, but because it is all collected from the sea, we call it our Sealadon glaze.

Janine grew up at the beach on the North coast and for very many years, she would collect beach pumice each time she returned to visit her parents. After a large undersea volcanic eruption out in the pacific ocean about 15 or so years ago, there was a substantial ‘raft’ of floating pumice that was blown across the pacific and onto Australian shores arriving here on the South coast in around 2013/14. This material is still to be found on some remote beaches, where it washed up and got stranded in the sand dunes and coastal grasses.

Pumice is an interesting rock. It’s an aerated volcanic glass composed mostly of felspathic minerals. These minerals (magma) are very viscous when hot and when forcefully ejected from a volcanic explosion under the sea, the trapped gasses in the rock, created under the intense pressure of the volcanic process are suddenly released. They can’t escape from the viscous magma quickly enough and so expand rapidly exfoliating the rock as it cools. Fluffing it up, like aero chocolate, Not unlike the way that grains of rice are ‘exfoliated’ into rice bubbles in a similar synthetic process.

We also found cuttle fish on the beach during our walk, cuttlefish ‘bone’ is made up of calcium. Many sea creatures utilise calcium from sea water to create their shells and carapaces. Calcium is a very good high temperature flux. So we worked out a recipe of 15 to 20% of cuttle fish bone and 80 to 85% of pumice works very well together. It’s also about the approximate proportions that we find them in together on the beach.