What a dummy I am! I've often had customers ask me for 'French Butter Dishes'. They have always, ALWAYS, explained that these are great for keeping your butter cool on the table. I have also always said I don't make them, but I never admitted it was because I just couldn't see how they could possibly keep the butter cool and I didn't want to sell them something and get it back because it didn't work. Besides, they're fiddly to make.
Now the current (Sept/Oct) issue of Pottery Making Illustrated has an excellent article by Keith Phillips on what he calls the 'Cloche de Beurre' or 'Beurriere'. And he explains that they keep the butter FRESH! Quite a different thing from keeping it cool! Fresh I can understand, yes. The seal created by the water in the base of the dish means that the butter doesn't oxidize, or pick up unpleasant odours, or otherwise go nasty.
Awright! Beurriers coming up! Thank you, Mr. Phillips!
BTW, update on the canister set customer: I went down to see her and came away with a paint sample which she wants to match. It's a pale creamy yellow so shouldn't be too hard to do. I promised to make some tests and come back and show them to her so she can approve the colour before I make the set. She struck me as one of these ladies who don't have enough worries. Sounds silly, but the result is that they try to control everything in their lives to the -nth degree because now they can. She explained several times that in her old kitchen everything was co-ordinated, even the towels, so I guess she's doing it again. She won't be easy to please but I'll give it a shot. She did surprise me at the end of my visit, though, by getting out quite a comprehensive tool kit in order to put a dab of paint on a stick for me. The serious tool kit didn't 'tell' with the pure white carpet, the white nylon sheers, the precisely aligned china ornaments.... hmmm.