The value of crud to studio potters like myself lies in its ability to stick to porcelain. Porcelain clays are notoriously difficult to work with when it comes to joining handles and other attachments to pots. I understand why this is so, but you probably don't. If you'd like a detailed explanation, send a PM to John Hardly. I don't want to be bothered with your idle curiosity.

Anyway, an effective porcelain joining slip can be made by pulverizing a mix of 50% dried porcelain clay and 50% dehydrated crud in a mortar and pestle and adding water to the resulting mix until it is of a creamy consistency. Just dip the ends of your handles in the stuff and slap 'em onto the pots. Guaranteed not to come off or develop joining cracks.

If you don't use the entire batch, just mix a packet of dehydrated French onion soup mix with what's left and it makes a great dip for potato chips.