Marie Lu

@Pres thank you, I will give it a try! @Mark C. I think you guys are right and I am kinda relived because I feel like a poor connection is easier fixed than a clay/glaze issue.

@Bill Kielb thank you so much for your response. You made a good point and now that I think about it I definitely have noticed when wet sanding my bisque that sometimes there would be little bubbles coming through the water, meaning there is space between the handle and mug. I always thought that this is probably not a huge deal since the glaze will make handle and mug stick together super well but I guess I was wrong… I always worried way more about clay body and glaze fit and making durable good glazes but I guess good construction is just as important. Your handle certainly looks like it will never come off that mug! Thanks again for your input. Alle the best, Marie

@Pres thank you so much for your advice. I never heard of “magic water” but would like to try it. Do you recommend a specific recipe? Best, Marie

Dear community, I hope I am uploading my question in the right section, if not feel free to move it. So I made a mug about 2,5 years ago that I gave to my sister. Yesterday she told me that the mug cracked by the handle (see picture) although she does not recall anything happen to it. Looking at it I feel like it most be an expansion issue that must have caused the crack to happen. I am just surprised that this would happen after such a long time! I am self taught and have been making pottery on and off for about 10 years now. In the last year or two I also started making my own glazes. Pottery is really complex in my opinion and producing something that is not of great quality is always something I worry about a bit and even sometimes make me question if I should pursue pottery it all since I learned everything myself. So having something like this happen, a mug breaking years after making it, really makes me question how I can unsere that my pottery is good and durable. Do you guys also think it is an expansion/stress problem that caused the crack? And do you have any methods beside the ice water/boiling water test to check for good glaze fit? Thanks for taking the time to read my post. Have a great day! Marie

@Minno worries at all, really interesting topic. Maybe you can tag me somehow if you share the Tests you will run, I would be interested in hearing about it. Also thank you for taking the time to responding in depth about matte glazes. I am also thinking about running some tests, bringing up the CaO and cutting back on the MgO in my glaze and see if this will affect the melt. Would this mean that a glaze containing higher amounts is Mg0 will always appear not fully glossy because of that fact that it does not melt?

Hi @BobMagnuson, thank you so much for your in depth response. If I got it right then regarding my glaze problem I maybe should take out the magnesium for my calculation, calculate the base again so I get a better balance of the R20/RO ratio and then add magnesium only for other reasons. Would you suggest a cutoff/limit regarding the Mg0 so a functional glaze that can be put on dishes is still produced?

Hi @Min, I am trying to make sense of the things you and bob are saying. Could you maybe explain why some of the strontium, magnesium, calcium would precipitate out of the glassy matrix in a slow cooled matte?

@BobMagnuson hi Bob, thanks for your response. Could you go a little bit more into detail about what you mean by the magnesiumalumino-silicate eutectic ? Sorry I have not heard about this yet. And when you say you don’t think it would form at cone 6, does this mean that when fired to a higher temp this eutectic would form? Thank you , Marie

Thank you fights for the quick answers! @Min I have made similar observations, the glaze that showed significant less gloss after the 6 hour boil has also been in the dishwasher almost every day for about 6 month now without any change in appearance. So I also feel like this test might just be too harsh. I wish I would have a put a regular porcelain mug from the store in too just to see how a commercially made one would hold up. @Callie Beller Diesel thanks for the warm welcome. Interesting that colorants do seem to have such a strong effect, even with good base recipes. Makes you really think that you always need to run tests even if it looks good on paper. Fingers crossed that you will be successful with the line blends. @Bill Kielb I agree that not all glazes are winners even when they look good on paper. I feel like though that maybe this test is too harsh because other glazes (variegated slate blue from mastering cone 6 glazes and a stable glossy glaze) also suffered through this test. Going more into the direction of glossy would be a good idea but I am trying to create a satin finish with the 6:1 ratio + slow cool. Thanks again for your time and Input

Hi everyone, I am new to this forum and wanted to share some results from the soda ash dishwasher test I ran to test my own glazes which is leaving me quite confused. (Sorry for any grammar mistakes, I am not a native speaker ;)). So I have been working really hard on developing my own glazes and finally, after a lot of trial an error, came up with a couple I really like. Before sending them to a lab now I thought I should do the lemon and soda ash test. So a made a 5% soda ash solution and boiled/ simmered my pieces for 6 hours. After that they were dull and white from the soda ash. When rinsed they would look completely normal again but as soon as the water dries off - dull again. i really did not expect these results because I tried to pay attention to R20, RO, Silica and Alumina levels. Maybe someone can check my recipe to see if I missed something or is this whole soda ash test simply not a good test to determine the durability of a glaze? I am feeling a little down about it all right now, so any help is greatly appreciated. I attached the base recipe for you guys. The colorants for the glaze are: A) 1.2 % nickel carbonate 0,5% cobalt oxide, 8% zircopax, 5% rutile B ) 0,5 cobalt oxide 7% zircopax 5% rutile C) 5% titanium dioxide 5% tin 3,2 % red iron oxide i fire to cone 6 in my electric kiln Thanks for your help, Marie