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Any Good Reason People Don't Seal Unglazed Clay With Other Finishes?


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#1 GavJ

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Posted 17 June 2014 - 05:10 AM

After extensive searching, I am unable to find much or anything in the way of people using wood type finishes on unglazed fired pottery, in place of refiring with glazes.

 

For example(s), terracotta or possibly even raku +

* polyurethane coats

* drying oils like linseed

* beeswax

* for a different coloration and look, something like a drying oil combined with limewash

etc.

 

Obviously none of that is appropriate for, say, oven use, but for tableware, why not? Coming from more of a woodworking background, these things seem straightforward and intuitive, but the lack of any actual examples of them I can find gives me pause.



#2 Chris Campbell

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Posted 17 June 2014 - 05:27 AM

Are you asking about dinnerware that food would be served on?
If so, consider the flavor transfer, staining from various sauces, damage from acid foods, absorption of smelly oils and spices ... then move on to what a pain they would be to clean and maintain. Think of someone leaving food on them overnight.
For non functional, decorative work all your finishes are options to try and many potters use them.

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#3 Stellaria

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Posted 17 June 2014 - 06:48 AM

I've used beeswax on some of my milk-fired ware.
As far as unglazed table ware, though.... Well, try it. Try drinking out of an unglazed cup. How does that unglazed rim feel? Now run a spoon or fork over the surface of an unglazed bowl or plate. Set your teeth on edge? It does mine.
Poly finishes are either not food safe or have dubious wear reliability. Resins smell weird. Beeswax doesn't hold up and doesn't really impart an actual finish anyway. Glaze is the most durable and inexpensive option. Sure you *could* use other things, but why bother when you'd come away with an inferior result in comparison?

#4 TJR

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Posted 17 June 2014 - 08:11 AM

Many Earthenware potters seal the feet of their work with terra sigilatta, which is a fine clay silt. See the work of Walter Ostrom.

Stoneware potters do not require sealing the bottoms of their pieces for functional ware as they are vitrified, which means that the body is tight, and not absorbent.

For my high school students, when they are making mugs at cone 06, I have them glaze the bottoms. I then fire them on prongs. I do the loading and firing, so this is not an issue of having glaze on the bottoms.

How many times did I say bottom?

TJR.



#5 Chilly

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Posted 17 June 2014 - 02:41 PM

Many Earthenware potters seal the feet of their work with terra sigilatta, which is a fine clay silt. See the work of Walter Ostrom.
Stoneware potters do not require sealing the bottoms of their pieces for functional ware as they are vitrified, which means that the body is tight, and not absorbent.
For my high school students, when they are making mugs at cone 06, I have them glaze the bottoms. I then fire them on prongs. I do the loading and firing, so this is not an issue of having glaze on the bottoms.
How many times did I say bottom?
TJR.


Too many !

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#6 Benzine

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Posted 17 June 2014 - 03:05 PM

I agree, with the right, fine gentleman from up North.

Like TJR, I use low fire, for my classroom. So I allow glaze on the bottom, of some projects, and stilt them.
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#7 Angie Days

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Posted 17 June 2014 - 05:49 PM

Hello! Watch this, is a “comal” kind of a clay grill which is seal whit a “cal” wash and then put in direct fire.

see how the egg don't stick to the surface.


There is another way with milk and garlic.






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