With a pottery maker, nothing more frustrating when tiny cracks ruin a “masterpiece” we have spent so much time and effort working and taking care. And there is nothing more painful than knowing or seeing (or breaking one by yourself) a work you have just finished turning into a hundred fragments just for a split second of carelessness. I have gone through these traumatic experiences many times; and on a few occasions I have been fortunate enough to learn a few tips for cracks / breakage rescue. With these tips for pottery making, hopefully you can apply and rescue your masterpieces.
Depending on how dry / wet the “work” is, we will use different rescue methods:
1 / When the clay is still wet
Since it may not be covered, after about 24 hours you realize your product dries out too quickly (but the clay is still wet) and cracked, the way to fix this crack would be to use clay with the same wetness – preferably from the leftover clay pieces when making the product from the day before to fill this crack as this clay has the same moisture / hardness as your piece. It is very important to use clay with a similar hardness to the product, as when the crack is filled, the whole clay block / piece will continue to dry at the same rate. When one part of the work dries faster or slower than others – this is why the clay cracks. Before “fill”, you use a serrated rib to score – scratch the area around the crack, and score a piece of clay for filling. I usually sweep the slip on the two sides that will come in contact, and continue to use the serrated rib to fill the cracks and finish this surface initially. You should score this surface relatively carefully, because scratching the surface will have the effect of compressing the clay (compress), making the clay / product harder than if you do not scratch. After you have scratched relatively well, use a normal (non-serrated) rib to complete the surface: smooth, or add textures, textures if needed.
2 / When your product has dried to the bone dry state
This means that the product is finished and has dried to the point of coarse heating, you discover a few very small cracks appearing at the joints of two different parts of the product: like seams, seams. handle of cup / cup with body of cup, etc. These lines are in English known as hairline crack – hairline cracks. These cracks can be very frustrating, or you might think this small heated and enameled will cover. However, these cracks will actually become even bigger when heated, and even bigger after the second firing (enameling). Therefore, it is best to cure this crack before heating the product.
How to fix it?
The cure is very simple, very cheap and very effective. You need some clay of the same kind as the clay you use to make the product – the drier the better, and a little vinegar. Put a few pieces of dry clay in a small bowl (you won’t need too much clay to fix a hair-thin crack), you pour a little extra vinegar into the bowl – not much vinegar is needed because after the clay dries. Dissolve in vinegar – you want a relatively thick paste – like slip or thicker. Once you have the mixture, use a brush to remove the slip and fill in the cracks. “Fill in” here includes the sweep of the surface area around the crack. Then wait for the surface to dry and repeat the process one or two more times.
3 / For a more serious case such as a broken part leaving a bone-dry piece, you can re-attach this broken part as it was
Mixing mixture: vinegar, honey (I use maple syrup, but maybe any kind of thick honey will work), dry clay chips in 1: 1: F1 ratio. Then operate similar to the steps in item 2 I described above. I have successfully attached the broken stalk of a balloon to this method. My balloon – after rough firing and enameling – looked completely intact with no marks of breakage or breakage.
4 / After coarse heating
Like I said – hairline cracks that you might not see before firing will appear more pronounced. Or sometimes if the product is heated too early – the product is not 100% dry; has not been “exploded” in the kiln but may crack, sometimes to a large scale – during the firing process. To fix these cracks, I use a liquid mixture called “bisque fix”. You can use a small and thin spatula to push the bisque fix into the crevice or any area you need to fill or fix; wait for it to dry, then do so again 2-3 times. Finally, you can use sandpaper to make the surface look even and beautiful before enameling and firing as usual.
5 / For works you only burn raw, not enamel
In addition to bisque fix you can also use epoxy. Epoxy consists of two ingredients that are usually contained in two separate jars. When mixing these two ingredients in 1: 1 ratio; you will get a soft, flexible mixture that can be used to shape, shape. After 24 hours the epoxy will harden completely. There are hard epoxy types, such as concrete and waterproof; that are used to “patch” water pipes or connections in water pipes. There are people who use epoxy as the main material for sculpting (instead of wood, clay, stone, etc.) I am not qualified enough to do so because 24 hours from epoxy can start to be used until the 100% hard time period is too short. I often use epoxy to repair or repair products; because a 24 hour period is just enough for me to “correct” the epoxy used to fill the cracks to match the rest of the work. I don’t know how if it is heated to the enamel heating temperature of the ceramic; how will epoxy react, so I only use epoxy with products that only need to be heated but not enameled. Note that the color of epoxy can be different from your clay color; so you will have to think about how to minimize this color difference (coloring, painting the whole piece, etc.)
To summarize the following:
- If the clay is still wet: use clay with the same wetness and slip to cure cracks; remember the score on both sides will come into contact.
- If the clay is dry bone dry and only cracks are needed: use a vinegar & dry clay mixture.
- If the clay is dry bone dry and it is necessary to attach two or two broken parts: use a mixture of vinegar, syrup and dry clay.
- For cracks appearing after rough heating: use a bisque fix mixture. I don’t know if bisque fix is popular or sold in Vietnam; so I share a photo of ingredients of bisque fix in this article.
- For products that are only pre-heated, not enameled: you can use epoxy.
Hope you will always make perfect products. And if these cracks / cracks ever appear, then I wish you successful rescue of your products!
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