Hyn Patty Posted April 10 Report Share Posted April 10 I've been using a commercially made bisque mender for years that I just love. But it's no longer available of course - Coloramics. Sadly I do not know the ingredients to try to duplicate their formula. I've tested several other bisque menders trying to find a good replacement that doesn't cost an arm and a leg. I just don't like any of them. Amaco Bisque Fix comes well recommended but it's pricy even before adding in shipping and is a far larger jar than I am likely to ever use up. Most of the other commercially made replacement bisque menders I have been testing shrink WAY MORE than the Coloramics product I had been using. For example: Mayco's Clay Mender is horrible. Shrinks badly and fires to a pink color. So, who has good bisque mender recipes to share? I've found some that use paper clay mixtures, some that use my own clay but adds vinegar or soda ash, or a little glaze (or all three). Low fire to cone 04 will do but up to cone 6 is also nice. Any suggestions you care to share here? Obviously making and testing my own versions is underway right now in my studio and I can make whatever I need practically for free instead of paying $30 for some product plus shipping. Ideally the lower shrinkage the better and I need it to be strong and fire white. I've always been wary of paper clays and concerned about how strong they are after firing since it opens up more voids and is more porous than the original. Also paper clay is a real PITA to get into tiny hair fine cracks. Opening up cracks in bisque ideal but is only feasible under certain circumstances and not in others. Please share your thoughts and recipes. I'm sure I'm not the only one who will benefit from input. Thank you! Once I settle on one that works really well I will be glad to share it here for others to try. Quote Link to comment Share on other sites More sharing options...
Hyn Patty Posted April 10 Author Report Share Posted April 10 The one I'm testing now I found on Instagram and is this one and can be fired to whatever the base clay requires that you use: This recipe is for repairing cracked bisque before a glaze firing. add: 1 cup your clay slurry Add: about 1/4 cup shredded toilet paper Add: 1 1/2 TB vinegar. Any vinegar will do. Blend with an emulsion blender stick. Don’t skip this step. It should be the consistency of coarse toothpaste. You can add more paper to make it harder or more vinegar to make it pastier. Pack it into the crack. When it has dried dry sand it smooth. Glaze as usual. Rae Reich 1 Quote Link to comment Share on other sites More sharing options...
Hyn Patty Posted April 10 Author Report Share Posted April 10 I've also found this one on the Lakeside Pottery website. Anyone tried using this one and loved it? It is also based on using your clay and adding soda ash and sodium silicate. It's for making 1 gallon at a time so I'd need to cut that down a lot for smaller units. I don't have soda ash on hand to try it but I may get some. https://www.lakesidepottery.com/HTML Text/Tips/pottery-magic-mud-magic-water-paper-clay.htm Quote Link to comment Share on other sites More sharing options...
Hyn Patty Posted April 10 Author Report Share Posted April 10 Anyone here swap sodium bicarbonate for sodium carbonate? Different PH but baking soda I have seen mentioned to be used in place of soda ash. I might try that for a recipe test making bisque mender as well. Quote Link to comment Share on other sites More sharing options...
Min Posted April 10 Report Share Posted April 10 2 hours ago, Hyn Patty said: Anyone here swap sodium bicarbonate for sodium carbonate? Different PH but baking soda I have seen mentioned to be used in place of soda ash. I might try that for a recipe test making bisque mender as well. If you want soda ash (or your soda ash is old and has absorbed moisture) bake it in the oven at 200F for an hour if it's a small amount and it will then be soda ash. I've tried the magic water + slip + paper pulp, didn't work for me. I think it makes a difference what type of crack it is though. Rae Reich and Hyn Patty 2 Quote Link to comment Share on other sites More sharing options...
Hyn Patty Posted April 10 Author Report Share Posted April 10 Thank you, I appreciate that feedback, Min! You always have great tips and advice to share. I did order some soda ash (just one lb to test) as it's handy for a number of things, but I will keep the baking soda conversion using heat in mind. Very nice, thank you! Quote Link to comment Share on other sites More sharing options...
Min Posted April 11 Report Share Posted April 11 Thank you for your kind words, very sweet. Quote Link to comment Share on other sites More sharing options...
Jeff Longtin Posted April 11 Report Share Posted April 11 I have mixed up the "Magic Water" recipe and it works. One gallon water, 9.5 gm sod silicate, 3 gm soda ash. Soda ash is quite caustic so make sure to wear gloves, or a glove, if you have a cut on your hand. It does sting otherwise. If I recall the "clay" content was 2/3 clay powder and 1/3 toilet paper. Hyn Patty and Rae Reich 2 Quote Link to comment Share on other sites More sharing options...
Min Posted April 11 Report Share Posted April 11 (edited) Trying to logic this through, I wonder if all or some of the dry clay in the magic water slip should be roasted first to remove some of the shrinkage of wet clay to dry. Blender some of the dry clay into a powder and roast that. (outside with a mask) I know there isn't much shrinkage from dry greenware through bisque temps but there is appreciable shrinkage from slip to dry. Bisque temp might be too hot causing sintering but roasting at 900-1000F could be something to try. Or a blend of unfired dry + roasted + paper pulp + magic water. I can see testing increasing amounts of sodium silicate amount also. Edited April 11 by Min Rae Reich 1 Quote Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted April 11 Report Share Posted April 11 Quote Bob Chance on sat 17 may 97 My favorite bisque patch consists of equal parts calcined Kaolin and 100 mesh Kyanite mixed with equal parts liquid sodium silicate and white (Elmer's) glue until the consistency of putty. Apply and sand when dry. You can glaze over it. Bob Chance Min and Rae Reich 2 Quote Link to comment Share on other sites More sharing options...
Min Posted April 11 Report Share Posted April 11 3 minutes ago, High Bridge Pottery said: I wonder if pyrophillite could be subbed for the kyanite. I have some pyrophillite, I could try it. Patch colour is going to be different than body colour though. Quote Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted April 11 Report Share Posted April 11 I have never tried it myself, I wonder if changing the calcined kaolin for whatever clay body you are using would be a better colour match. Kyanite seems to have some expansion at hotter temps so I wonder if that helps it join the crack together. Quote Link to comment Share on other sites More sharing options...
Hyn Patty Posted April 13 Author Report Share Posted April 13 (edited) I did see Kyanite mentioned in a recipe along with sodium silicate on Digital Fire here: https://digitalfire.com/picture/3164 Looks like a cone 6 patch. I mostly do low fire fixes but I do have this one noted for higher fire projects. Edited April 13 by Hyn Patty Quote Link to comment Share on other sites More sharing options...
Kelly in AK Posted April 13 Report Share Posted April 13 I’m going to comment here not because I have a great answer, but because I’m keen to know how this unfolds. I have some ideas to share. My initial thoughts are calcined kaolin will counteract shrinkage and be white, so some percentage of it will be helpful. Kaolin or your current clay body is the best way to achieve color match, some percentage of that is necessary for a paste that’s plastic, can be pushed into cracks, and remain cohesive. The body clay is better because it’s going to mature at the right temperature. Strength is the tricky one in my mind. One critical thing is the “keying” of the paste into all the little nooks and crannies of the crack, pushing it in. Filling the crack, not just covering it (I’m preaching to the choir here, I know). Paper, as you noted, complicates that. It has its virtues, in general it can mend things many experienced clay people consider un-mendable. I could go on about it, suffice to say I’m not sure paper is a helpful ingredient in your case. It may be, I’m just not sure. Soda ash and/or sodium silicate I think of as helpful. ***DISCLAIMER: I am no ceramic engineer*** One effect they can produce is to reduce the amount of water needed in the mender to make it fluid, that allows you to better fill the cracks and reduces drying shrinkage. The other effect is as a flux, to fuse the paste together and ideally adhere it to the bisque as well. I have no good idea about the amount to use, other than it’s small. These materials have a melting point, both around ordinary bisque temperatures. Your firing temperature and how they interact with the other materials will affect their usefulness. Finally, considering the clay portion, if you use only kaolin and calcined kaolin then it’s going to be weak. Your body clay is going to produce something stronger, and soda ash/sodium silicate will compensate in fluxing power what you’re losing by adding calcined kaolin. Your work is great! Wishing you luck with testing. Hyn Patty 1 Quote Link to comment Share on other sites More sharing options...
Hyn Patty Posted April 23 Author Report Share Posted April 23 (edited) All right. For an initial test I have mixed up about 1/3 cup white earthenware slip (cone 06-04 that I got locally and ball milled it a few days) and to this I added about a tablespoon of vinegar. Mixed it up and it bubbled a little bit (a lot of the recipes mention vinegar but not sure why exactly). By morning it had settled on top as a clear fluid and the slip had become rather unplastic, sort of more like wet sand than slip. I poured off the excess fluid. Then I added about 1/2 a teaspoon soda ash and mixed it in well. It tried to form a hard crust so I had to put it into one of my mortars and use the pestle to grind it smooth again. I have a rather large ball mill but alas, not a little one. Maybe I should make myself a smaller porcelain jar and little balls for just such things ... but I digress! The last thing I added was 1 ml of sodium silicate, mixed well then a touch more. It became very creamy and lost the hint of grittiness. I have no idea how it will preform but now I'm going to test it. Not sure if the vinegar was actually any help at all or not but the soda ash and sodium silicate made sense. I'll let you know how well it works or doesn't. I'm going to test it filling in tiny defects and a crack in a bone china horse sculpture I want to glaze. My initial reaction is it has a good feel, much like the bisque mender I had been using and loved. I can always color adjust afterwards with a little airbrushed opaque white underglaze if needed over it to blend it in before I move onto coloring the piece. Wish me luck! I'll be firing it to cone 04. Edited April 23 by Hyn Patty Hulk and Kelly in AK 2 Quote Link to comment Share on other sites More sharing options...
Hyn Patty Posted April 23 Author Report Share Posted April 23 Might benefit from a small addition of gum arabic. It's rather fragile and the binder might be helpful. Quote Link to comment Share on other sites More sharing options...
Mark C. Posted April 24 Report Share Posted April 24 kyanite is something I use in my home made ITC mix and comes in many mesh sizes. Does not shrink The crystals are long and its one of the strengtening things say in mulite kiln shelves It great stuff Quote Link to comment Share on other sites More sharing options...
Kelly in AK Posted April 24 Report Share Posted April 24 Not wanting to veer off topic, but I tried, and settled on, kyanite as the groggy/temper portion of my stovetop earthenware clay body (It’s for personal use man, don’t hassle me!). I agree, it’s something special, worth a look. I can’t say anything about the color response, as I was using red clay. I see Tony Hansen has made a low shrinkage bisque patch recipe using just that and sodium silicate: https://digitalfire.com/picture/SpqnhMR7kv Quote Link to comment Share on other sites More sharing options...
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