Cleaning pottery & ceramics (or not)

Couldn't see anything on the forum on this subject posted previously - apologies if I have missed something on the subject.

The question is prompted by my latest purchase, a Tony Gant jug (or vase as I like to think of it) - here's a pic for a bit of added interest:



It had been used, which is ok, but there was a sticky residue left in the bottom. It was quite easy to remove, bit by bit, with pure soap and luke-warm water, and the gentle prompting of a small stiff paintbrush. I have been happy to clean previous gruby peices that were hard glazed and had no obvious surface damage with pure soap and water, on the basis that there was little damage it could do. However, for unglazed surfaces or where there is apparent damage, crazing, etc. I have left well alone for fear of making things worse. I know there are some well known tricks for cleaning glass, but have not seen much advice regarding pottery and ceramics. I would be interested to hear members advice for cleaning items or, indeed, whether they consider it a "no no" for the inexperienced.

I've hand washed pottery with both crazed and unglazed surfaces in warm water with no detrimental effects, but maybe I've just been lucky?

It will make the crazing look a lot worse until it dries.

The ones I avoid washing are naked raku pots and raku with surface metal oxides, unless I absolutely had to.

Depends on the clay / glazes in my opinion.

I find crazing on lower fired earthenware is much more likely to stain than the crazing on porcelain/stoneware, I assume because the crazing is tighter.

Personally I'd try and avoid/be very careful cleaning items with:

Gilding.
Easily damaged glazes. (raku / burnished etc)
Hairline cracks.
Over-painted designs.

If you have some something like tough water residue inside inside a pot, as long as the glaze is tough enough etc Cerium Oxide can be used to remove it.

Thanks for the advice Naomi and Potty.

Agree with avoiding the gilded, painted type of items - if your taking off grime, you're just as likely to take off the decoration as well. Hadn't heard of Cerium Oxide, but note its used for a number of cleaning/polishing uses. I have used baking soda previously for stubborn marks, and its obviously the slight abrasiveness that works. Again, this was only on hard glazed items.

I suppose the best advice is: be cautious and if in doubt, don't.

No one mentions bleach above? I've used it to clean the inside of glass before and it's recommended in wine-making to bring demijohns back from the brink. Dunno what Cerium Oxide is?

.......... so I have a white piece of the porcelain Stig & it's very grubby. I don't think the usual soap and water will do. First question is

1) Can I whack it in a bucket with a drop of bleach/water ? Second question is
2) Do I want it pristine and gleaming white?  

I don't think the usual soap and water will do

I think first & foremost is use it, before dismissing it. It may be all you need. I've certainly never needed anything more for surface grime.
When I have had deep staining (fat under the glaze in an old baking dish) nothing has shifted it.


Cerium Oxide seems to be a glass polishing compound, presumably like jeweller's rouge. Useful for getting particularly stubborn, insoluble, surface residues off a glaze (which is essentially a glass layer), such as carbonates, but not so useful for stains.

Bleach will act on stains (also Hydrogen Peroxide), but is unlikely to remove surface residues - the water is more likely to remove dirt than the action of the added bleach. Sometimes the dirt - soot - is embedded between the crazed glaze, and I haven't found bleach effective in removing it or minimising the colour since soot is basically carbon and bleach breaks up chemical bonds to destroy the colour and you can't get much smaller than carbon atoms.

Naomi TY, and second question; If you find something on a stall do you want it to be in slightly grubby 'original' state or in pristine, gleaming obviously cleaned and sanitised state with every mark removed?  In other words should I clean it?

If you're planning to sell it I'd go with uncleaned. I cant resist uncleaned items, they look 'fresh to market'.

NaomiM wrote:If you're planning to sell it I'd go with uncleaned. I cant resist uncleaned items, they look 'fresh to market'.

.................. so the Ebay seller who seems to have left a dead rat in the vase he sold was trying to appeal to people like you!  

I have some really filthy pottery for sale

studio-pots wrote:

NaomiM wrote:If you're planning to sell it I'd go with uncleaned. I cant resist uncleaned items, they look 'fresh to market'.

.................. so the Ebay seller who seems to have left a dead rat in the vase he sold was trying to appeal to people like you!  

Well people buy houses with mummified cats in the wall, so I'm sure there's a market for potted rat.   

dantheman wrote:I have some really filthy pottery for sale

I hve some too, but we may not be talking about the same thing.