Sunny Posted January 27, 2015 Report Share Posted January 27, 2015 What makes something "Dishwasher safe". Is it the type of clay? Link to comment Share on other sites More sharing options...
oldlady Posted January 27, 2015 Report Share Posted January 27, 2015 imagination only. Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted January 27, 2015 Report Share Posted January 27, 2015 I would imagine a clay body that doesn't adsorb water (I never know if it is 'ab' or 'ad' sorb) and a glaze that does not react with dish washing stuff (alkaline I think) Other than those two I can't think of more reasons why it wouldn't be safe putting it in. Link to comment Share on other sites More sharing options...
neilestrick Posted January 27, 2015 Report Share Posted January 27, 2015 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. Link to comment Share on other sites More sharing options...
Babs Posted January 27, 2015 Report Share Posted January 27, 2015 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. Link to comment Share on other sites More sharing options...
bciskepottery Posted January 28, 2015 Report Share Posted January 28, 2015 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. Link to comment Share on other sites More sharing options...
Sunny Posted January 28, 2015 Author Report Share Posted January 28, 2015 I use Laguna and Amaco glazes. What if it is unglazed and fired to 5? The reason I'm asking is I made some platters that are only glazed on top. The underneath has no glaze. Link to comment Share on other sites More sharing options...
bciskepottery Posted January 28, 2015 Report Share Posted January 28, 2015 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. Link to comment Share on other sites More sharing options...
PeterH Posted January 28, 2015 Report Share Posted January 28, 2015 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. Link to comment Share on other sites More sharing options...
Guest JBaymore Posted January 28, 2015 Report Share Posted January 28, 2015 Legal definitions......... "Microwave Safe" >>>>>>>>> http://www.astm.org/Standards/C1607.htm "Dishwasher Safe" >>>>>>>> isn't any! best, ................john Link to comment Share on other sites More sharing options...
Sunny Posted January 28, 2015 Author Report Share Posted January 28, 2015 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. 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. Link to comment Share on other sites More sharing options...
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