studiosoda

Hi everybody, so I have an update: Turns out that when my boyfriend made a new batch of this glaze he accidentaly took the recipe from the next glaze in the book which is a matte brown and marked it wrong. Ups.... mistery solved.... It's still an issue though as I have seen this glaze come out matte and glossy from same kiln, which seems to be because of different heat in kiln. Thanks for you help!

Thanks for your help guys. I will check with cones & load the kiln differently to see if that makes a difference and report back if I make any progress

Not yet, but I just ordered some and will test it. I just read through the specifics of my oven and found out that it is single zone, maybe that could explain temperature difference...

@Hulk This is the recipe: Feldspar 50 Whiting 20 Zinc Oxide 4 China clay 11 Flint 15 Red iron oxide 10% Good to know, thank you. If it's the cooling; when I fired in a huge kiln in the studio the same glaze came out matte (lowest shelf) and shiny (other shelf) from the same firing... Also I noticed another glaze I use come out fine (green) on the middle shelf and completely another color (blueish/grey) in the bottom shelf of my kiln... Therefore my question, if it's normal that glazes do that sort of thing.

Hi everybody! I have been testing glaze Nr. 255 from the book "The potters book of glaze recipes". It's an iron glaze for 1200°-1260°. On all my test tiles it came out glossy. When I did a firing in my studio (cone 6), some pieces from the same kiln came out glossy, some matte, depending on the shelf. I presumed it was that specific clay. I did further samples (in a tiny kiln) and on that same clay it came out glossy this time. The firing schedules could have been a bit different, I'm not sure as my studio does it. Now I did a firing in my own toploader kiln (1240°). All the pieces glazed with it came out matte - no matter which clay. They were all on the bottom floor. I'm wondering if they might be underfired? How come a glaze is sometimes matte, sometimes glossy? Does it mean it's underfired? Can the firing schedule play such a huge part on the outcome? I hope somebody has some advice Thanks! left is mate/right is glossy - same clay

Forgot to post an update: It was most likely the two firings combined with a too thick glaze. I did the same combo again with thinner glaze and one firing and they came out fine!

@Callie Beller Diesel Thanks for your input. I'm sure the refiring didn't help, they probably would have been fine with one firing. Another plate that was half the size also came out fine after the second firing, same glaze & clay. It might be the fact that they are big, flat dinner plates. I will try out different things and keep you posted about the results.

Thank you @kswan, I have never heard of dunting before, that is really helpful.

Hello everybody! Today I had a surprise when I opened the kiln and need help to figure out what went wrong. I made some dinner plates with this clay: Sibelco WMS2502 (stoneware clay). I used a △6 glaze that I found on glazy. I made some test tiles with the clay & glaze combo in a small oven in my studio and they looked perfect. When I fired the plates the first time it was a disaster. Basically the whole oven was underfired and the plates came out looking really matte and not finished. Also all other pieces with this particular glaze looked weird, some crawled and some clay completely couldn't handle this glaze. My studio fires to △6, but it seems like the oven is quite old and because it's so big it fires really unevenly and doesn't reach the right temperature. Some pieces came out okay that were on the top. So I thought I will fire the plates again to see if its the oven, but in a medium sized one, that seems to fire a little bit hotter . I fired a small underfired piece (little bowl) a second time and it came out perfectly. When I fired the plates the second time - △7 - they all came out broken, except one! -.- (See pictures) Now my problem is, that I have no idea where I went wrong. Is it the glaze/clay combination? Is it the the second firing? Is it because I only glaze them on one side? Could it be because some of it is recycled clay? Is the application too thick? I really appreciate any hints, as I'm a bit lost...