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Hello, I am a new member (and new to pottery in general) and have struggled to find the answer to the glaze defects I have been experiencing on previous posts in this forum. I am having trouble with pinholing/pitting/airbubbles (not sure exactly what to refer to it as). Most of my glazed pottery either has loads of little holes (this is especially bad with black underglaze topped with clear) or lots of tiny bubbles trapped beneath the surface. To provide a background, the clay I have been using is Scarva Earthstone ES5 Original White Stoneware Clay, which has a firing temperature of 1200-1290°C and some grog in. I have primarily been using Amaco velvet underglaze, which I apply on cone 04 bisqueware and top with Amaco clear gloss (HF-10), before firing to cone 6 on slow. I only use the standard programmes on my little Skutt Firebox as I have not figured out setting up my own yet (i.e. with soaks). Using tips from previous posts, I have tried wet-sanding bisque fired pieces before glazing, and making sure they are washed and dust free. I have also experimented with slow firing vs medium. The sanding helped a lot and I have fewer pinholes now, but am still getting loads of tiny little pits on (specifically) the black underglaze. I am not sure why this is different to the other colours or clear gloss over bare stoneware (but this still has lots of airbubbles underneath, they just aren't breaking the surface). I have attached some close-up photos of the issues, which hopefully are good enough quality to be visible. I am not sure what is causing this and would be really grateful if anyone has any ideas? Thanks, Ellie
About 10 years ago, I took several ceramic classes and fell in love with the way Strontium Crystal Magic worked with other glazes. I attached a picture of Strontium Crystal Magic Warm with a spray of Water Color Green that I made in a community college class. Fast forward 10 years and I cannot get anything close to those results. The second picture shows the same glazes with a kiln controller set to a standard medium speed firing schedule to cone 5 with a 12 minute hold time. There are tons of nasty little pin-holes, and although I don't mind the color, it is nothing like I was expecting. The recipe that I copied from San Juan College is as follows: Strontium Crystal Magic Custer Feldspar 2400 Whiting 900 Strontium Carb 660 6 Tile Kaolin 780 3124 Frit 240 Lithium Carb 240 Titanium Dioxide 720 Bentonite 120 Total: 6030 Yellow Iron Oxide 121 (2%) Sooo... I noticed online that my SJC recipe has slightly different ratios than the one I found on https://ceramicartsnetwork.org/ceramic-recipes/mid-range/strontium-crystal-magic-warm/. Also, my copy from SJC says "6 tile kaolin" while the one on the website says EPK. Is my recipe written wrong? or is my firing schedule and temperature causing the pin-holing and color difference between the pot 10 years ago and now? I know that glazes are super complicated, but I just don't even know where to start and would really appreciate some help. Thank you for any help! Erin P.S. I am so sorry the images are huge... I wasn't sure how to re-size them
Hi Everyone. I'm having major problems with pinholing and pitting. I am getting hundreds on pin holes on only the outside of small pots. I am using tucker's mid smooth stone and bisqueing to 04 with a 16 minute hold. I am dip glazing using amaco white with a 16 minute hold. I have noticed after I dip glaze that lots of popping bubbles appear on the outside of the pots in the glaze. More hold time? Is my kiln broken? Any help would be good . Thank you.