You begin with a shapeless lump of wet clay.......
By firing pots and dishes in the oven with a visible fire,
you slowly see the glazes melt until the surface is of a satin sheen.
Red-hot, the pots are taken out of the fire and put into the sawdust where the green
copper oxide subtly changes into a gold-coloured copper finish.
when all this is successful...
and the pot has no imperfections and has a beautiful crackle...
then I feel myself to be an ALCHEMIST:
or at least...
I was born in Amsterdam (The Netherlands) on December 3, 1938. After highschool I completed
a course in the Chemical Department at the HTS of Amsterdam. Afterwards, I started my
professional career at Philips, to improve physical and chemical processes for the
production of electronic parts.
This was also the start of my work in my free time on the fundamentals of ceramics: CLAY ;
it is great fun to delve with your hands in the "mud" but with your head in the clouds..
And so I found a new hobby (besides tennis and walking in the mountains).
After my retirement (at the end of 1998) it was very clear to me that I was
developing as a potter in the tradition of Raku: simple in form with a surprising beauty.
The objects are mainly thrown on a potter's wheel or made from sheets of clay.
The clay I work with is from Creaton No. 468 with 40% chamotte (0-0.5mm).
After drying, the objects are fired for the first time - the so-called biscuit firing -
in an electric kiln at approx. 1000 C. After that, the glaze is applied to the pieces.
The objects are removed from the kiln with a pair of tongs when they are still in a red-glowing state and are immersed in a barrel of sawdust. The effect can vary from a weak to a strong reduction, with a lot of smoke. During the cooling-down stage, the characteristic crackle-effect of the Raku technique appears.
The glazes are made from basic materials and I am often experimenting to improve the
existing recipe or to develop new recipes.
At first instance I tried to “remake” Gerstley borate with a combination of materials which gives the same chemical formulae.
(calculated with my "homemade" glaze program)
This can be realised by the addition of :
The end recipe is surprisingly simple:
Because of my chemical background I am very interested in the more "fundamental" side of the glaze
and that was the reason to make my own glaze program to calculate the Segerformulae.
An example of this calculation, an experiment with a Barium titanate ( a heritage of my
tech.ceramic period ) is given here. see Seger.
The glaze program - written in Excel 2000 - is available free and has other calculations besides the
Seger formulae; the lineair expansion coefficient; the surface tension and the weight % of the oxides.
As an example, here is a calculation of the crystal glazes from Lasse Östman given in the appendix
This is the most difficult part of the ceramic trade, although youre almost degloved
by the chamotte parts of the clay,throwing is fun, because you are creating something
new and although the disappointment can be very big when the pot breaks,
glazing and firing is fun because of the unexpected; you never know how things will
But selling is difficult, because it is hard to let a piece of you go. On the other hand
you cannot let your stock accumulate and you want the "wide world" to enjoy the fruits of my labour.
You can view my work (and get a feel) at:
for LINKS. click here