Studio Update : Week of 1/30
You know those weeks that just punch you in the gut and humble you a little bit? That was my week. I unloaded the glaze kiln early Monday morning and the results were bad. I had assumed that I finially had my glaze problems under control after doing rounds of glaze testing. I had chose the best one and tested it on two mugs in the test kiln before deciding it would be a good fit. The two mugs I had tested came out pretty good, there was only slight pinholing that could only be seen if you moved the cup around in the light. So I figured a small hold in the glaze firing would fix that. Any time I have heard about pinholing I have always heard of a hold in the firing as one of the tweaks to help with it. So on Monday morning you can imagine my surprise when I opened up the kiln, with over a month's worth of work in it, to find out everything pinholed and cratered like crazy. I even put back in the initial test mugs that were mostly good and they turned out really bad as well. I was trying to figure out where I went wrong because all my tests were consistantly good so did I apply the glaze too thick? Well, that's not the problem because my test mugs that got refired got worse and they were initially fine. After a phone call with my old professor who is a glaze chem wizard, we concluded that the hold in the kiln basically overfired my work. This batch of work is probably a lost cause, but I can try to dremel the glaze and smush a thick layer of glaze into the holes and refire. I refired 3 mugs, one I dremeled a lot, one a little, and one not at all. I wanted to test my options. I also did some test tiles of that same batch of glaze to make sure that the hold really was the problem. I also did a batch of test tiles where I added zinc oxide in 1, 2, and 3%. Zinc Oxide helps with the surface tension so it could possible help the glaze heal itself over while it is in it's viscous state, but it can cause problems with colors. I refired in a fast fire setting to cone 6. The dremeled mug turned out much better and leads me to believe that this is a solid fix, though it would take a lot of work as it still had patches of remaining craters in some places. I might return to that batch of mugs to try this at some point but for now I need to move on. The test tiles of the glaze turned out fine, so again that solidifies that the hold was the problem. The zinc oxide tests proved that zinc oxide is not a suitable option for the colorants. To try and fix the very minimal amount of pinholes I do have, I am instead going to try to bisque fire with a hold so that whatever extra impurities in the clay that are causing problems have the chance to fire out in the bisque rather than the glaze firing. Since the test tiles consistently show good results, I am testing this next round with little cups. For each color glaze, I am going to test two cups. One I will pour glaze into and one I will paint it in. I want to see if there is a difference in the application. These cups will be bisqued with a hold. All in all this week has been a nightmare and a set back for sure. It's frustrating to have work that you are really proud of result to failure. Ceramics can feel like a giant collection of losses at times so I do truly believe that you have to be a resilient person to handle it. Despite a busy semester of deadlines, at the end of the day I have my whole life to make things and by taking time to figure out the glazing, I am setting myself up for a better future of making.
Image 1: another round of test tiles waiting to be fired
Image 2: Zinc oxide test tiles that prove zinc oxide will not work
Image 3: some ruined work!!!
Image 4: a close up of one of the worst mugs after dremeling