Bornholm has a very varied subsoil, and have representations from most of the geological periods, from ancient times to the present.
The center of the island and the northern parts are primarily granite.
The west coast from Rønne to Hasle, is primarily Jurassic deposits with clay deposits, overlaid with a sand plain.
The south coast from Rønne to Dueodde is very varied and covers a fairly broad geological period from 500 million years ago, to the present.
The geological diversity of the entire island provides good opportunities to find diverse materials. Within short distances you can e.g. find granite, and also quartz and feldspar, slate, limestone, ocher and basalt.
Also kaolin, stoneware and low-fired clay in a wide range of compositions and expressions.
In addition, faults, deposits and erosions have made large parts of these materials roughly available in many places. Most of what one needs in a ceramic production, can thus be found here on the island.
The time from approx. 1950 to 1970 marked a shift in the ceramic tradition in Denmark and on Bornholm.
There was a switch from wood firing to gas, oil or electric firing in the kilns.
There also was a switch from 1950, where mainly local materials where used, to 1970 where mainly materials purchased on the world market where used in production.
At the same time there was a changed in the competitive situation, for the individual potters, from having local potters as competitors, to a situation, where potters where in competition with the world market instead.
During this period, there was also a decline in the production at the tile factory “Hasle Klinker”, and in the subsequent 20 years from 1970 to 1990, production in the factory died out completely. Thus, almost all traces of factories and single potters that knew about and utilized Bornholm's raw materials disappeared.
To make tests from an extremely wide range of materials, that we can find on Bornholm, is interesting because it gives us deep understanding about the materials, we use every day.Ideally, we would like to use only local materials in our work in the future, we always have a second agenda, when searching for ressources.How can we make this possible, when we also need to tread carefully in nature and follow rules and regulations?The remains of the old tile factory, Hasle Klinker has stored a pile of clay from when the factory was in use.Big amounts of his clay we have been kindly donated and has been our main ingredient in bigger pieces.It feels good in many ways to use what today is seen as a waste material and what we can get in big amounts.
This clay is one of the best known clay on Bornholm.
It is a 200-million-year-old red clay, that has been used by potters and factories in various ways in generations.
We have used this clay as an ingredient for our glazes in 20 years, but have found it very interesting as an ingredient in our different clay bodies too.
The clay found in the Sose area is known as the stoneware clay the Hjorths Factory used and still uses in their producton.We use it in various ways and just love to visit the beach from where many different variants are revealed.The beach is know for its iron rich stones and sand too.
Two things make it fairly easy, to find and use clay on Bornholm:
The clay formations are revealed all along the west coast. If you walk along the coast, you will find, that the sea has made it possible for us to find the clay that normally very often, is hidden under a meter of soil.
The water in the Baltic Sea contains very little salt. It is therefor possible to use it from the beach.
Granite felspar, quartz and kaolin/china clay are our precious and main ingredients in both clay, slip and glaze, (along with wood ashes and straw ash).
Opened 1824 and still in use. Granit is 17 billion years old. This granit can make a beautiful amber coloured glaze, when you fire it at stoneware temperatur.
