Jim and Marge Wade on fri 6 apr 01
Can anyone tell me more about resist slip (also referred to as "crank
slurry")? I've read of it being applied to bisqueware prior to sawdust
firing. Is it different from a regular slip that is applied at the
wet/greenware stage?
Thanks.
Marge
Marianne Bornet on mon 9 apr 01
Hi Marge
This is an area which I am exploring at the moment with varying results. My
general idea is to apply the slip, draw into it and then smoke the pot
(previously burnished and bique fired). The slip is then supposed to
conveniently drop off the pot like an eggshell
- I wish ! I have tried this previously with great results in Britain using
a slip made from Crank clay - which is unobtainable here, of course.
All my little test tiles worked very well using various slips made from
different grogged stoneware bodies. The minute I applied the slip to a form,
it either stuck on or I damaged the the surface trying to scrape it off.
Last week I tried using Dave Roberts resist slip recipe which he uses with a
glaze covering in Raku firing. (3 parts china clay and 2 parts flint). This
was relatively successful but did stick in some places. I also tried with an
ordinary stoneware slip mix of 60 ball clay and 40 china clay with the same
results.
I am starting to wonder if the problem lies with my smoke firing technique.
Because of the restrictions on burning etc here, I do the firing in a metal
container (with a row of holes around the bottom) in the fireplace with a
glass enclosed hearth - draws really well. I put some sawdust in the bottom
with loosely rolled up newspaper, the piece in the middle with rolled up
paper all around it and on top, sprinkle more sawdust in and set it alight.
It goes like the clappers and I think that it possibly just gets too hot and
the slip gets fired on in certain places. If you try it with a proper slow
sawdust firing it might work.
If you try out these recipes, I would be interested to hear how you get on
either through Clayart or directly. I'll let you know if I get any
successes.
Godd luck
Marianne in sunny and hot South of France
kruzewski on mon 9 apr 01
Hi Marianne, and anyone else that wrote on this subject.
When I was first learning to pot I went to a North Wales Potters workshop with
Jacqui Atkin. She used a resist slip on her pots before smoke firing. They were so
beautiful and the method was so easy I tried it with great success.I'm absolutely
no expert on this, I only know it works.
The pots need to be burnished and low bisc fired-about to 900 centigrade - sorry, I
know you all fire to farenheight, and I don't have a conversion to hand.
The pots can then be decorated in two ways.
1. Use masking tape where you want the smoked patterns to be. I don't know if you
call it masking tape in US - decoraters use it, it's paper based and comes on a
roll and is buff brown colour with one sticky surface. Once the tape is on you add
this simple slip - half clay slurry/slip - from your wheel, not too thin ANY CLAY,
and half sand.
I used to live right on the coast (I live about 2 miles in land now) in a village
that was literally built on old sand dunes. I used to go out into the
park/playground behind my house with a small tub of clay slurry and tip in an equal
amount of the mostly sand soil from there. I mixed it up, plant roots and all
(although they are not vital!) and daubed the mixture all over the pot. I then
dried it off - I had an Aga then which was great for that, and then I lit a
newspaper fire in the grate and burnt the pot till I thought it was done -
difficult to tell because you can't see the smoke effect. Once the pot has cooled a
bit I would peel the slip off like an eggshell.Where the masking tape had burnt
away there was a carbon pattern, elsewhere, where the resist had cracked there was
delicate smoke veining. I used terracotta clay mostly but the best effects were on
porcelain. The slip "shell was also really interesting - although the outside was
rough and blackened the inside of the slip shell was beautiful - smooth with the
smoke pattern burnt into it. I loved this so much I even spray varnished it (to
keep it together) and mounted it on card - it's still on my wall (how sad am I?!)
2.Apply the slip/sand slip straight onto the burnished pot then scrape through the
slip before it dries - otherwise it tends to chip away.The pot can then be smoke
fired. Because the slip has been broken up by the decorating technique it wont peel
easily, I used to put it under a tap and wash it off using a green (washing up)
scouring pad. It wasn't difficult to remove but was messier. So much more
satisfying peeling off the shell.
To finish the pots I heated them slightly and applies furniture wax which, once it
was cool, I'd polish up.
Marianne, you say you think you are firing the slip through the temperature in the
being too high - I would have thought it would have peeled away from the pot
easier. Sometimes I got my pots too hot and the carbon from the smoke would burn
out - I'd just get a shadow, but I never had a problem with getting the resist off
- especially if it was applied using the masking tape technique.
As I say, I'm no expert, but this always worked for me - real low tech and simple.
I'd like to know if you try and if it works for you.
best wishes,
Jacqui Kruzewski
still cold and wet in North Wales - but that's what makes it so green here!
Marianne Bornet wrote:
> Hi Marge
>
> This is an area which I am exploring at the moment with varying results. My
> general idea is to apply the slip, draw into it and then smoke the pot
> (previously burnished and bique fired). The slip is then supposed to
> conveniently drop off the pot like an eggshell
> - I wish ! I have tried this previously with great results in Britain using
> a slip made from Crank clay - which is unobtainable here, of course.
>
> All my little test tiles worked very well using various slips made from
> different grogged stoneware bodies. The minute I applied the slip to a form,
> it either stuck on or I damaged the the surface trying to scrape it off.
>
> Last week I tried using Dave Roberts resist slip recipe which he uses with a
> glaze covering in Raku firing. (3 parts china clay and 2 parts flint). This
> was relatively successful but did stick in some places. I also tried with an
> ordinary stoneware slip mix of 60 ball clay and 40 china clay with the same
> results.
>
> I am starting to wonder if the problem lies with my smoke firing technique.
> Because of the restrictions on burning etc here, I do the firing in a metal
> container (with a row of holes around the bottom) in the fireplace with a
> glass enclosed hearth - draws really well. I put some sawdust in the bottom
> with loosely rolled up newspaper, the piece in the middle with rolled up
> paper all around it and on top, sprinkle more sawdust in and set it alight.
> It goes like the clappers and I think that it possibly just gets too hot and
> the slip gets fired on in certain places. If you try it with a proper slow
> sawdust firing it might work.
>
> If you try out these recipes, I would be interested to hear how you get on
> either through Clayart or directly. I'll let you know if I get any
> successes.
>
> Godd luck
> Marianne in sunny and hot South of France
>
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