This is the post where I skip straight to the good stuff: my test results and reviews of nine commercial bisque mending products. If you want to see how I got these results, and see photos of my results, check out this post describing my testing process.
Let me start by saying that none of these products are the holy grail of mending ceramics. Mending cracks and breakage at the green and bisque stage is an unpredictable process that does not always yield good results, even with a product that has worked well for you before. What I found in my results is that none of these products are a cure-all for every single issue at every single stage of the process. I’ve avoided anything like a rating system for these products, because it makes more sense to tell you about each product’s strengths and weaknesses.
Best for re-attaching broken bisque. Harder to use on greenware. When filling bisque cracks, a hairline crack re-appeared after the firing. I got better results with re-attachments when I built up some extra material around the mend and then sanded it smooth.
Best for re-attaching broken greenware. Was not very effective at filling cracks. Hard to use and not great results for bisque mending. Performs more like a slip thickener than anything.
Effective for both re-attachments and crack filling at the bisque stage. It is not good for greenware. Filling greenware cracks with it will actually cause more problems later on, as the clay shrinks more through two firings than this material will.
I didn’t have a lot of luck with this material, except possibly as an aid when mending cleanly broken greenware. Doesn’t seem very effective as a bisque mend. The fired result was bumpy and unattractive.
Best for greenware repair. Not as good for bisque repair. When filling cracks, they usually re-appeared as hairline cracks. The slow drying and high shrinkage of this product as it dried made it frustrating to use. I was able to re-attach pieces at both the green and bisque stages, but hairline cracks emerged along the bisque mend. If you cover it with an opaque glaze, you may be able to disguise the hairline cracks that I found hard to avoid while using this product.
Another material I didn’t have much success with. It seems most effective in helping repair cleanly broken greenware. As a crack fill, it was underwhelming. As a bisque mend, it allowed too many cracks to appear. A big caveat is that this is designed as a low-fire product, but that information is not listed on the product packaging or the manufacturer’s website. By the time I found out, I had already taken it to Δ6 in a glaze kiln. So, it may perform better at its proper temperature.
This product has one very specific use: filling bisque cracks. It can be used for bisque re-attachments, but it is challenging and inconsistent, and it was not good at all for mending greenware or patching green cracks. Filling greenware cracks with it will actually cause more problems later on, as the clay shrinks more through two firings than this material will. In fairness, this product is marketed specifically as a bisque crack filler, and that it does quite well.
My least favorite product on this list. It was messy, frustrating to use, and didn’t work on even one of my test mends.
This material initially performed well when it came to re-attaching broken greenware. It was not effective as a crack filler. However, the good results in the lower temperature firings literally fell apart in the Δ6 kiln. This material may have better success at lower firing temperatures.
I want to thank my partner in this testing venture, TJ Erdahl. He contacted the manufacturers of these compounds, who were all generous enough to send me free product for this testing project. Naturally, I also want to thank Amaco, Archie Bray, Apt II, Marx, The Ceramic Shop in Philadelphia, Duncan, and Spectrum for sending me their products. Hopefully some of these test results will help you find the most useful products for your own studio practice. Happy mending!