How to test pottery

We all know how to test for damage..or do we?
I for one have always wondered about ringing a pot to test for cracks,does it work on all shapes and sizes? and what is the best way to hold odd shaped pottery so it resonates properly?

It works for a lot of shapes and sizes, but the tone you expect to hear changes from pot to pot.

For example if a pot has a lot of crazing, it will make a thud, but it will make a much worse crackly thud if it is cracked.

The body of the item is also very important to the tune you expect to hear. Hard paste porcelain makes a very nice ring, much like that of glass.

Earthenware makes a bit of a thud, but again much worse when actually cracked.

The test is mainly used to detect hairline cracks and often a chipped item will ring quite nice.

You need to make sure to hold the item so that you do not dull the sound with your hands.

I rest most items across the tips of my fingers (as little finger as possible).

It is by no means foolproof and a test I use as a quick detection, but still check an item toughly after, more so if it sounds like it may be cracked.

It's not the be all end all test it has sometimes been made out to be on the telly.

If it is a solid item I doubt this test would be of any use.

Regards,

Potty.

By the way, the best way to understand this is to start listening to pots that you know to be perfect and ones that you know to be cracked.

does anyone use UV light to test for restoration?

Requested by Dan:

To look for restoration, you examine an item for a subtle change in colour and / or consistency on the item.

If you believe there could be restoration on an item, you can use the following test.


Testing for restoration using your teeth:

Press the restored area gently against the enamel of your tooth, if it feels soft compared to the rest of the pot, chances are it has been restored.

Pressing with a nail also works, but you need to be more sensitive to notice the difference, it is a lot more apparent with your teeth.

Be careful not to press to hard, as the restoration can be easily damaged itself.


This test is very good, but if the item has very light restoration (e.g. thin coating over a hairline crack to disguise the damage can sometimes seem as hard as the body of an item) it can still be difficult to know either way.


Potty.