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salt contamination/was hurricane...

updated wed 2 feb 00


Janet Kaiser on tue 1 feb 00

Sorry you had so much hurricane damage and salt water to deal with. But =
all is not lost? I suppose it will depend on the amount of salt in the =
Don't laugh=21 Sea water can vary quite drastically in its saline qualities.=
you are in a shallow bay behind a reef or sand bar, the salt content or =
will be higher than the ocean beyond. Unless a river is feeding fresh water

Anyway, that is beside the point. I found the following notes on SALT:

Common salt is sodium chloride, NaCl a colourless, soluble, crystalline
substance. It is believed to assist glaze suspension, but its main use in
ceramics is in the production of salt glaze. The re-crystallisation of salt =
cruets can cause trouble: a crazed earthenware glaze will allow dissolved =
to permeate the body and may lift the glaze away. A chemical salt is a =
the reaction of an acid with a base. E.g. sodium sulphate, barium chloride, =
A glaze may be considered as a salt. Or as a salt into which additional =
is dissolved. Salts are, in general more stable than their separate

Maybe that first sentence could give hope? I have never heard of anyone =
NaCl to a glaze to aid suspension, but there you go...

The bit about salt in cruets is only too true. That is why we ask that tiles=
The Path be totally waterproof and preferably vitrified. We get one
hundredweight of salt per acre per year fall-out from the sea here. Once =
gets into anything -- ceramics, cement, stone walls -- it is a big problem. =
=22corrodes=22 from within. First it pushes out big white mould-like crystal
=22blooms=22. Folk here call it Salt Peter -- not sure whether it is true =
or not -- and it is supposed to be poisonous. Anyway, it can push large =
off houses where the salt has seeped in with the rain. Certainly did to our
house when we had some new windows put in by a bunch of cowboys... All the
cement fill around the windows fell off within two years. We then had to =
that part of the house demolished and rebuilt because once you have salt
contamination, you are stuck with it forever.

One of the tiles we have in The Path which is earthenware and clear glazed =
had a crack in has already started to loose the glaze along either side of =
crack. (Sorry, Heidi, but our worries were well founded). The high rainfall =
have had recently has not been enough to dilute the air-borne sea salt and =
has started to do its evil work... After just two months=21 I expect the =
tile will
slowly disintegrate as the salt builds up.

But this is of course salt penetration into a fired body and not what you =
to know about your =22contaminated=22 materials. I tend to go along with the
recommendation of mixing a test batch. You may find that it has no ill =
effect at
all. That is as long as it is just glaze materials and not the clay... I =
definitely throw any dried clay that was soaked away.

Hope this helps?

Janet Kaiser
The Chapel of Art: Home of The International Potters' Path
Criccieth LL52 0EA, GB-Wales, UK
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