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london slip

updated fri 15 mar 02


Jennifer Assinck on wed 13 mar 02

Hi Gavin and Edouard:

I was very interested in what might be an analysis of the clay at my cottage
north of Peterborough, Ontario. The clay was harvested from the bottom of
the lake.

Locals refer to it as clay because it cracks when it dries and it is very
fine and slippery, but I cannot imagine throwing with it because it feels
too "short" and does not hold together. When raw, the clay is a dark grey.

I have tried it as a substitute for Albany slip in Cone 6 glaze recipes, but
I have no Albany slip to compare the results to. I am too new to pottery to
have experienced Albany slip and wondered if one could have throw with that.
It makes a lovely dark brown glaze(like the glaze on Brown Betty
teapots)when fired at Cone 8. As a glaze at Cone 6, it does not smooth out.

I am just starting my experiments, and so far, mixing it with other clear
glaze materials to make it melt at Cone 6 has made it a pale honey colour,
not as golden as honey. I have only done the 25/50/75 proportions, and will
be trying less melters to see if I can get a darker colour.

I did try ash from maple syrup production mixed with this local clay, with
the intention of calling it Maple Syrup Glaze. It came out looking like a
pale maple syrup, but with a bit of a greenish cast, probably from the ash.
Not appetizing.

Gavin, why are you calling it London slip? I must have missed that post.

Jennifer Assinck
Newmarket, Ontario

>From: "Edouard Bastarache"
> > Here is an average of 15 samples taken in different places
> > in our province, from Julien Cloutier's book(page 60),
> > "Materiaux du Ceramiste Quebecois":
> >
> > SiO2 56
> > Al2O3 16.2
> > TiO2 0.8
> > Fe2O3 5.6
> > CaO 4.3
> > MgO 2.7
> > Alcali 4.5
> > LOI 7.7