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Dishwasher Safe


Sunny

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Vitrified clays would be best. As for glazes, some will etch out over time due to the harsh soaps, but it depends on the glaze and the type of soap being used. Shiny pots can lose a little shine, but that happens with commercial dishes, too. I consider everything I make to be dishwasher safe.  And I wouldn't be able to sell half as many if I told people they had to be hand washed.

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Some low fire decals get pretty scratched,low fired decorations I've seen wear away and were prob not food safe in teh first place. 

Having visitors at the mo. some of my stuff should be labelled not safe if handled by humans>>> a few mugs bit the dust , careless positioning, not fussed, just observing.. fortunately my favourite is out of bounds by other tea drinkers, selfish lady here.

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Dishwasher soaps are more harsh than the ones used for sinks.  The water is hotter.  So, your glaze finishes need to have the durability to withstand that type of repeated washing without discoloring, fading, etc.  Best discussion and treatment of durability for glazes is in "Mastering Cone 6 Glazes" by Hesselberth and Roy.  http://www.masteringglazes.com/  Vitrification is important in terms of absorbancy and being able to place the ware in an oven, microwave, or freezer.  What you want is the complete picture:  a vitrified clay body that has durable and fitting glazes. 

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If your clay vitrifies at cone 5, unglazed should not be a problem on the bottoms.  Laguna has absorbency, shrinkage and other data for their clays on their website.  I try to keep absorbency to 2% or less, but shoot for clay bodies with 1%.  Stoneware or porcelain.  If the glazes are rated Cone 5/6, likely okay . . . but it may be worth doing a couple of the durability tests just to make sure  -- running them through the dishwasher repeatedly, lemon slice on glazed surface to see if it discolors, etc.  Mastering Cone 6 Glazes lists tests you can do at home; these are preliminary tests, not finals, though.  Other books also describe them.  Try a google search for glaze durability testing.  If they fail  the at home tests, find other glazes.  For finals -- especially for leaching (although with commercial glazes you really don't know what to test for as you don't know what the glaze is made of), you need to submit to a laboratory.

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I would imagine a clay body that doesn't adsorb water (I never know if it is 'ab' or 'ad' sorb)

 

Absorb is the term for the usual process, adsorb refers to a different, and more unusual, process.

 

http://en.wikipedia.org/wiki/Adsorption

Adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface.[1] This process creates a film of the adsorbate on the surface of the adsorbent. This process differs from absorption, in which

a fluid (the absorbate) permeates or is dissolved by a liquid or solid (the absorbent).[2] Adsorption is a surface-based process while absorption involves the whole volume of the material. The term sorption encompasses both

processes, while desorption is the reverse of it. Adsorption is a surface phenomenon.

 

 

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If your clay vitrifies at cone 5, unglazed should not be a problem on the bottoms.  Laguna has absorbency, shrinkage and other data for their clays on their website.  I try to keep absorbency to 2% or less, but shoot for clay bodies with 1%.  Stoneware or porcelain.  If the glazes are rated Cone 5/6, likely okay . . . but it may be worth doing a couple of the durability tests just to make sure  -- running them through the dishwasher repeatedly, lemon slice on glazed surface to see if it discolors, etc.  Mastering Cone 6 Glazes lists tests you can do at home; these are preliminary tests, not finals, though.  Other books also describe them.  Try a google search for glaze durability testing.  If they fail  the at home tests, find other glazes.  For finals -- especially for leaching (although with commercial glazes you really don't know what to test for as you don't know what the glaze is made of), you need to submit to a laboratory.

 

I use Standard clay. I went on their website and most of their clay, including what I use is over 1%.  This is what is listed for the 2 clays I used. I fired to Cone 5.

 

 266 DARK BROWN CLAY (Cone 4-6) Gives reduction-like dark brown color in electric kiln. Smooth and plastic. Good for all techniques. NON-TOXIC%20copy.jpg

Shrinkage:  11.5% at C/4, 13% at C/6.

Absorption:  2.4% at C/4, 1.4% at C/6.

 

308 BROOKLYN RED CLAY (Cone 4-8) Red stoneware body with sand and grog. Oxidation firing yields brick red at cone 6 and deep warm brown at cone 8. 

Shrinkage:  12% at C/4, 13% at C/8. 

Absorption:  2.5% at C/4, 1.0% at C/8.

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