Potters & Sculptors - Making Rock from Mud
Everyone has experienced this - Not all of our glazed pots are pleasing .....We unload our glazed pots from a warm kiln with the excitement of a 5 year old- waiting to get down to that shelf which holds the one piece we really want to see......and Yeck - there it is. Not what we planned, perhaps even ugly. Sometimes it's just a flaw that makes it unusable/ un-sellable, a tiny spot that we missed glazing or a drip that dripped too far.
I sell my work so salvaging a piece means more than just liking it- it means potential revenue lost. But regardless of the final resting place of your work - we all like to salvage our mistakes.
Reglazing is a tricky business. In the studio where I teach I try to get my students to understand that it's a risk to reglaze and that the piece may very well be even worse off. Existing glaze remelts and moves, warpage and blistering can occur, and other over fired looking effects can overcome.
I tell my students it's a waste of kiln space and glaze to refire/reglaze a piece that only your mother would like - so be sure it's a worthwhile piece to begin with. Sometimes I have found great new combinations by mistake in the process of reglazing though. That said.
The Application of new glaze - Heat the pot up - microwave- heat gun - whatever will get it hot. Then reglaze it. This makes the new wet glaze dry quickly on the surface and adhere better. If it's just a small spot you need to heal then feather the glaze in over the area. If it's a dip - then be sure to have a nice big fat clearance at the bottom so it doesn't run to the base. Sometimes I put those pieces on a biscuit, depending on how close the first glaze came to the base.
Heat Helps- Reglazing can be a Risky Business.
Sometimes on a refire, one is emboldened to try something really different, particularly on a pot that is a total loss, such as the following.
This is the way my single fired mug came out of a reduction firing. The glaze (Malcom Davis Shino) was not able to bond to the raw B-mix 5 clay. It shrank more in the firing than the body and the poor bond caused crawling more than crazing. The glaze was also not completely melted, accounting for the flakes. In thinking about refiring the pot, I knew that I was going to need a very fluid glaze to penetrate the cracks and voids in the shino, and to adhere the flecks of shino firmly to the body. The first step was to knock down and remove curled flecks of shino that were standing in high relief, particularly around the rim where someone might want to put their mouth. I did that by tapping on those areas with the wooden handle of a hammer to break off all the projections and loose pieces. I then dipped the mug in heavy cream consistency Floating Red glaze, dried it with a heat gun, dipped it again, dried it, and after cleaning the bottom off, it was ready to fire to cone 6 in my electric kiln.
I was very lucky with my choice of Floating Red as a covering glaze. I've seen other glazes behave horribly on top of true shinos. The finished product totally exceeded my expectations, flowing nicely into and accentuating all cracks and voids, and flowing gracefully down the chattered texture in the middle of the mug. Part of the rim was still rougher than I wanted for mouth contact, so I used a diamond grit sanding block and fine wet/dry carbide sanding paper to smooth it. The rim is now smooth enough for even my tender lips.
There is an excellent set of glaze application tips --- Glazing for Success: 12 Tips to Help You Master Pottery Glazing from Annie Chrietzberg posted on Ceramic Arts Daily. If you suffer a lot of glaze defects, it is highly likely that one of these factors is the culprit. I give this article five stars.
I want to share that before starting the process of reglazing (very rarely) with the heating of the piece, I always degrease its surface (finger prints) wiping it with a cloth soaked with cellulosic thinner or dichloromethane (dry cleaning solvent, much more efficient and...toxic)