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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 |
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. |
"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 |
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 |
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 |
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? |
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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