jpdes Posted January 14, 2015 Report Share Posted January 14, 2015 I make slab built platters and shallow bowls using cone 6 clay and glazes. I like a flat bottom, no foot look but not the resulting large expanse of bare clay on the bottom of the piece. I am wondering whether spraying the unglazed bottom with a solid coating of a solution of clear frit would enhance the aesthetics and long term functionality. The frit solution would be applied after the final glaze firing. I am thinking of using a solution of Ferro Frit 3124 or 3134. The pieces would then be fired upside down (glazed surface against the shelf) to the melting temperature of the frit which would be in the range of 1450 - 1600 degrees F (cone 016 - 012). I am thinking the cone 5-6 glaze would not soften at these temperatures so the glazed areas against the shelf should not be a concern. It would require an additional firing so obviously not feasible for production pottery but would it make sense for low volume decorative pieces? Link to comment Share on other sites More sharing options...
oldlady Posted January 14, 2015 Report Share Posted January 14, 2015 why not a wash of underglaze done while making the pot? underglaze will not stick and if it is thinned to a wash consistency it should present no problems. no additional firing needed. Link to comment Share on other sites More sharing options...
MMB Posted January 14, 2015 Report Share Posted January 14, 2015 An issue that would arise is the clay body maturing to cone 6 and then trying to get the glass melt to really adhere to a nearly if not vitrified body. Glass gets sticky but Im not sure if it would really be the best to last the test of time. Im sure some others on here will better inform. My 2 cents Link to comment Share on other sites More sharing options...
neilestrick Posted January 14, 2015 Report Share Posted January 14, 2015 I don't think there's a good way to do this that is worth the time and effort. Plain old frit would be difficult to apply, and would probably craze really badly when fired. The typical way to get glaze on the bottom is to fire on stilts, but those don't tend to work very well at cone 6. If you just want color, an underglaze wash would do the trick. The other option is to adjust your form so that the unglazed area is minimized, such as adding feet or a foot ring. Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted January 14, 2015 Report Share Posted January 14, 2015 If your clay body's already vitreous, adding frit as a sealer won't add anything to its long term functionality. And just because a glaze isn't in full melt flow, doesn't mean nothing at all is happening at cone 016-012. I could see some glaze mixes beginning to sinter at that temp, and then you have a lovely rim of kiln wash on your plate. If you wish to attempt this, I'd make sure to do a test on a slab of waste clay coated on kiln wash, just to make sure. But I agree wth Neil, there are less-involved solutions. I'd be inclined to make some sort of drawing, texture, or other pretty surprise on the bottom, if it's the blank space that is bothersome. Link to comment Share on other sites More sharing options...
Babs Posted January 14, 2015 Report Share Posted January 14, 2015 The Soda wash that Chris Campbell supplied the recipe for gives clay a subtle sheen which I find attractive. Do a search on that. Or is it pos. to "burnish the bottoms, I know the sheen from that may does reduce/vanish with the higher temp but the clay surface would be of a different texture. Old Lady has a great suggestion, I sometimes do this with an oxide and a fan brush and just put an abstract swirl on bottom of large hand made platters. Link to comment Share on other sites More sharing options...
jpdes Posted January 15, 2015 Author Report Share Posted January 15, 2015 Certainly some helpful suggestions, thank you. I went back and reviewed discussions about the soda wash described by Chris Campbell. Does this flux to an extent it would result in sticking to a shelf if used on the bottom of a piece in a cone 6 firing? And a similar question with underglazes as, in my experience, some flux to a certain degree. If using underglazes on the bottom/against the shelf should one be attentive to choosing those that fire to a matte finish? Link to comment Share on other sites More sharing options...
bciskepottery Posted January 15, 2015 Report Share Posted January 15, 2015 Some underglazes can flux, or at least transfer color to your kiln shelves. If you use an underglaze wash (underglaze diluted with water), that should be less of a potential problem. A fluxing problem could also be a combination of the underglaze and the clay body interacting together. The soda ash wash I use (1/8 to 1/6 cup soda ash to 1 cup of water, I think Chris uses 1/4 cup soda ash) is rather diluted and should not stick to kiln shelves. To be on the safe side, you could fire the platters on clay cookies made of the same clay body. Another option is to put some type of texture on the platter bottoms and leave it raw. Link to comment Share on other sites More sharing options...
jolieo Posted March 5, 2015 Report Share Posted March 5, 2015 Hi What about terra sigilata? From what I've read ( i am new at this: it is all second hand) it is possible to fire terra sig to any temp above sintering, just losing high gloss at the higher temps. Also can color w oxides. IDK if it would stick to shelves. Jolie Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.