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Old 24-08-2005, 11:42 AM
Bill H
 
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Default Waterproofing and Frostproofing Clay Pots

Hello

I have some clay pots that I have brought back from Africa, they are clay
that has been fired in a kiln but not glazed.
The clay after firing is a terrcotta colour.

I need to protect them from the UK elements, rain and frost, no room
indoors!

Someone suggested painting them with PVA glue which I have done, when sunny
they have a shine however everytime it rains they turn white!!

Any ideas

Many thanks

Bill H


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Old 24-08-2005, 12:46 PM
Mike Lyle
 
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Default

Bill H wrote:
Hello

I have some clay pots that I have brought back from Africa, they

are
clay that has been fired in a kiln but not glazed.
The clay after firing is a terrcotta colour.

I need to protect them from the UK elements, rain and frost, no

room
indoors!

Someone suggested painting them with PVA glue which I have done,

when
sunny they have a shine however everytime it rains they turn

white!!

Any ideas


I wouldn't have recommended PVA glue, for the reasons you have
discovered. Better is an inside-and-out coating of masonry
water-repellent. But that won't protect against expansion of the
contents in a bad freeze-up: this could also crack the pots, but I
don't think it happens very often. The shape of the pot would matter,
I think: conventional conical ones are probably safer than ones which
are narrower at the top than in the middle -- we had a wooden
water-butt break when it froze solid.

--
Mike.


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Old 24-08-2005, 05:02 PM
JennyC
 
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Default


"Bill H" wrote in message
...
Hello

I have some clay pots that I have brought back from Africa, they are clay
that has been fired in a kiln but not glazed.
The clay after firing is a terrcotta colour.

I need to protect them from the UK elements, rain and frost, no room
indoors!

Someone suggested painting them with PVA glue which I have done, when sunny
they have a shine however everytime it rains they turn white!!

Any ideas
Many thanks
Bill H


If they are not frostproof, there's not a lot you can do about it. They really
need firing at a very high temperature.

You could perhaps try to find a local potter and ask if they will fire / glaze
them for you.
Jenny


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Old 24-08-2005, 08:41 PM
Chris Hogg
 
Posts: n/a
Default

On Wed, 24 Aug 2005 10:42:25 +0000 (UTC), "Bill H"
wrote:

Hello

I have some clay pots that I have brought back from Africa, they are clay
that has been fired in a kiln but not glazed.
The clay after firing is a terrcotta colour.

I need to protect them from the UK elements, rain and frost, no room
indoors!

Someone suggested painting them with PVA glue which I have done, when sunny
they have a shine however everytime it rains they turn white!!

Any ideas

Many thanks

Bill H


Most clay pots aren't glazed. Depending on the composition of the clay
and the temperature they're fired at (typically between 800 and
1000C), they may or may not be frost proof. But you yourself can't
tell, and coming from Africa (where frosts aren't widespread) it's a
fair bet that they aren't.

Rain on its own shouldn't do them any harm, although permanently damp
pots may start to grow algae, moss etc. Nor will frost harm them if
they're bone dry (it's water freezing in the pores of the pot that
causes them to shatter).

There are products available from DIY sheds that are supposed to
waterproof brick walls and concrete. Perhaps you could paint them with
that but it might darken the colour. Whether it can be applied _over_
the PVA, I don't know. If it can't, as JennyC suggests, you might find
an obliging local potter who would re-fire them for you on a 'biscuit'
schedule to burn it out. There would be some fumes though, but most
raw clay gives off fumes on first firing, and a potter would be
familiar with that and ventilate his pottery accordingly.

I'd still be worried that they weren't entirely frost-proof and make
sure I kept them really dry.



--
Chris

E-mail: christopher[dot]hogg[at]virgin[dot]net
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Old 25-08-2005, 08:12 PM
 
Posts: n/a
Default


Chris Hogg wrote:
On Wed, 24 Aug 2005 10:42:25 +0000 (UTC), "Bill H"
wrote:

Hello

I have some clay pots that I have brought back from Africa, they are clay
that has been fired in a kiln but not glazed.
The clay after firing is a terrcotta colour.

I need to protect them from the UK elements, rain and frost, no room
indoors!

Someone suggested painting them with PVA glue which I have done, when sunny
they have a shine however everytime it rains they turn white!!

Any ideas

Many thanks

Bill H


Most clay pots aren't glazed. Depending on the composition of the clay
and the temperature they're fired at (typically between 800 and
1000C), they may or may not be frost proof. But you yourself can't
tell, and coming from Africa (where frosts aren't widespread) it's a
fair bet that they aren't.

Rain on its own shouldn't do them any harm, although permanently damp
pots may start to grow algae, moss etc. Nor will frost harm them if
they're bone dry (it's water freezing in the pores of the pot that
causes them to shatter).

There are products available from DIY sheds that are supposed to
waterproof brick walls and concrete. Perhaps you could paint them with
that but it might darken the colour. Whether it can be applied _over_
the PVA, I don't know. If it can't, as JennyC suggests, you might find
an obliging local potter who would re-fire them for you on a 'biscuit'
schedule to burn it out. There would be some fumes though, but most
raw clay gives off fumes on first firing, and a potter would be
familiar with that and ventilate his pottery accordingly.

I'd still be worried that they weren't entirely frost-proof and make
sure I kept them really dry.



--
Chris

E-mail: christopher[dot]hogg[at]virgin[dot]net

If you touch your tongue to a clay pot and it sticks then it is not
frostproof. This tip was given to me by a lady potter in Suffolk. If it
is not frost proof then you would be better off buying one that is. It
is all down to the firing temperature as other correspondents have said
Tony Bull
www.caterpillarfountain.co.uk



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Old 26-08-2005, 12:18 PM
John McMillan
 
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Default


I have some clay pots that I have brought back from Africa, they are clay
that has been fired in a kiln but not glazed.
The clay after firing is a terrcotta colour.

I need to protect them from the UK elements, rain and frost, no room
indoors!


Some of the pots that Ikea (i.a.) sell appear to be dip painted with
clear acrylic or silicone. The pots are normally made in Vietnam
or Myanmar or somewhere with even worse safety standards but certainly
no frost. I've often wondered about this technique myself. If I got
a porous non-frostproof pot and gave it a couple of coats of marine
grade acrylic varnish, then it would be waterproof and so frostproof,
wouldn't it?
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Old 26-08-2005, 01:21 PM
Mike Lyle
 
Posts: n/a
Default

John McMillan wrote:
I have some clay pots that I have brought back from Africa, they
are clay that has been fired in a kiln but not glazed.
The clay after firing is a terrcotta colour.

I need to protect them from the UK elements, rain and frost, no
room indoors!


Some of the pots that Ikea (i.a.) sell appear to be dip painted

with
clear acrylic or silicone. The pots are normally made in Vietnam
or Myanmar or somewhere with even worse safety standards but

certainly
no frost. I've often wondered about this technique myself. If I

got
a porous non-frostproof pot and gave it a couple of coats of marine
grade acrylic varnish, then it would be waterproof and so

frostproof,
wouldn't it?


The Vietnamese ones are under-fired as a rule, yes. But you can't
rely on paint or varnish for waterproofing: with weathering and
expansion and contraction the film will crack -- often invisibly --
and these cracks will let in water. Masonry water-repellent, inside
and out, is the only chance, I'd say.

--
Mike.


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Old 26-08-2005, 06:04 PM
Chris Hogg
 
Posts: n/a
Default

On 25 Aug 2005 12:12:34 -0700, wrote:


Chris Hogg wrote:
On Wed, 24 Aug 2005 10:42:25 +0000 (UTC), "Bill H"
wrote:

Hello

I have some clay pots that I have brought back from Africa, they are clay
that has been fired in a kiln but not glazed.
The clay after firing is a terrcotta colour.

I need to protect them from the UK elements, rain and frost, no room
indoors!

Someone suggested painting them with PVA glue which I have done, when sunny
they have a shine however everytime it rains they turn white!!

Any ideas

Many thanks

Bill H


Most clay pots aren't glazed. Depending on the composition of the clay
and the temperature they're fired at (typically between 800 and
1000C), they may or may not be frost proof. But you yourself can't
tell, and coming from Africa (where frosts aren't widespread) it's a
fair bet that they aren't.

Rain on its own shouldn't do them any harm, although permanently damp
pots may start to grow algae, moss etc. Nor will frost harm them if
they're bone dry (it's water freezing in the pores of the pot that
causes them to shatter).

There are products available from DIY sheds that are supposed to
waterproof brick walls and concrete. Perhaps you could paint them with
that but it might darken the colour. Whether it can be applied _over_
the PVA, I don't know. If it can't, as JennyC suggests, you might find
an obliging local potter who would re-fire them for you on a 'biscuit'
schedule to burn it out. There would be some fumes though, but most
raw clay gives off fumes on first firing, and a potter would be
familiar with that and ventilate his pottery accordingly.

I'd still be worried that they weren't entirely frost-proof and make
sure I kept them really dry.



--
Chris

E-mail: christopher[dot]hogg[at]virgin[dot]net

If you touch your tongue to a clay pot and it sticks then it is not
frostproof. This tip was given to me by a lady potter in Suffolk. If it
is not frost proof then you would be better off buying one that is. It
is all down to the firing temperature as other correspondents have said
Tony Bull
www.caterpillarfountain.co.uk

Not an absolute guarantee, and I'd have put it the other way round (if
your tongue doesn't stick, it's probably frost proof) but as a rough
rule of thumb I'd go along with that.


--
Chris

E-mail: christopher[dot]hogg[at]virgin[dot]net
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