Topic: The coffee filter cone that didn't want to come clean

[Peripatetic Phil]

For about the last fifteen years, I have been using a glazed ceramic coffee filter cone to make my coffee -- they are simple, quick and efficient.  But yesterday, when I came to take one out of the top shelf of the dishwasher, I noticed it was still dirty.  So I left in in there, intending to re-wash it with last night's dishes (I have spares for just such emergencies). 

Last night I cooked a curry (of course) -- Chicken Madras with Samphire -- moved the cone to a different location (just in case that one spot wasn't getting the full force of the water), put in the various curry utensils and dishes (all heavily stained and curry/oil-laden) and turned the dishwasher on.

When I got up this morning, I opened the dishwasher, and was staggered to see that the coffee filter cone was just as dirty as before;  I checked everything else, and all else was spotless.  Thinking that either the glaze had started to break up, or that the cone had inadvertently been exposed to great heat, searing the stains on, I removed it from the dishwasher intending to spray it with Dettox "Mould and Mildew" spray (my standard way of dealing with heavily-stained things, including turmeric stains).  To my absolute amazement, the stains just rubbed off the cone as I moved it, from the contact with my fingers alone.  A quick rinse under the tap, and it was spotless, ready for my morning coffee.

So what is the explanation, chaps (and chapesses) ?  How comes one utensil, made of glazed ceramic and not heavily stained, remains impervious to the best efforts of the dishwasher, in two different locations, while other things, heavily coated and stained with curry, come out spotless ?

Yours, staggered.
** Phil.

[Razor]

Phil,

Got no idea mate, really is a strange one?

Ray