Regardless of how great your pottery ware is in terms of design, you might observe a crack or two. This is especially true if you are a beginner artist. The best pottery stage to pick on a crack & stop it before it deepens is when the piece is greenware. However, if you have failed to do so successfully and the clay has reached its bone dry stage, the method of fixing such cracks can be a bit tedious.
But, before you start the repairing process, you need to understand what exactly bone dry clay is?
Bone Dry Clay: What Is It?
Bone Dry Pottery is a stage in the pottery process where the greenware has dried to its maximum possible extent before being fired. When you hold bone dry clay in your hand, it would feel similar to the room temperature and not cool like its previous stages.
This is because a good amount of moisture has evaporated from the clay, which was originally lowering its temperature. The process might take as long as a week depending on how thick the clay piece is.
Features of Bone Dry Clay
|Surface Warmth||Not as cold as previous stages of pottery ware|
|Fired||No (Stage before firing)|
Where Do Cracks Occur in Bone Dry Clay?
Cracks start mostly at the points with structural weakness. Moreover, cracks can develop in sections where a coil is connected with another and even in areas where 2 walls meet. You might notice cracks building up through the molding process or after there is added stress like new parts or coils. It is normal for cracks to appear in vulnerable sections as a clay piece starts to dry out!
Soft leather or leather hard stage is the best point to correct the crack, and the problem can worsen if the pottery piece attains a bone dry stage.
How to Correct Cracks in Bone Dry Clay?
Now, this might seem counterintuitive, but a great way to correct any developing cracks in bone dry clay is to dig in further. Clay is known to have a memory. To erase this memory of cracking, you need to score deeper into the cracks and make it larger than it originally is.
Next, place a small piece of soft scored clay into this crack and now compress the same with the help of a rib to ensure the surface smoothens out. If you are looking for a good pottery toolset to complete this process, you can try the Meuxan Pottery Tools Clay Sculpting Set. This set of 30 pieces is ideal for your daily crafting needs. Make sure the surface is completely leveled up so that the crack doesn’t expand during the firing process.
You also need to ensure that the wet clay you just patched into the crack dries out to the bone dry stage. If you fail to do this, when firing, the main piece and the piece in the crack would expand and fire at a different rate. So, you might see cracks even post the firing process. Make sure you allow the patched piece to dry out perfectly. This will help heal the cracks depending on the moisture content of the piece.
Once the cracks in the bone dry clay are repaired, if your clay still looks weak, the key is to wrap your pottery piece in plastic. This will allow the clay’s moisture levels to equalize and hence help with even drying out. Make sure you practice caution when adding water or moisture to the crack at a given point. Water might lead to swelling in the crack & cause the crack to deepen further. So, if possible, the key is to refrain from adding any additional water to the crack. Simply use some moist clay to fill in these cracks.
When Do Cracks Form In Bone Dry Clay?
There are specific situations when you might encounter cracks in the bone dry clay. Let us check out some advice on ways to proceed.
Coiled pots are known to develop some thin spots. This is especially true if you are a beginner learning the use of ribs. This tool helps create an even thickness in the wall. If you see that the thickness is uneven, you should shore up these areas with some clay to prevent any cracks or collapses.
When creating coiled pots, you need to be mindful when establishing initial connections. This is applicable in sections that involve connecting a coil to the clay piece floor or when connecting a coil to another. Establishing these connections tends to be tricky, especially if the clay piece is at its bone dry stage.
The key is to score well & ensure that the connections fit in properly. A thoroughly compressed part will aid in minimizing potential cracks. Another problematic area in a pottery piece is the rim or lip section. Most potters complain of pots starting to crack or crumble from the piece’s top section running downwards.
To prevent this, the key is to ensure a thorough thickness. Quickly start correcting any cracks that develop at the rim/lip before it expands in the downward direction.
When at its bone-dry stage, your choices for repairing are very limited. So, you might not want to waste too much time repairing the piece. In case there are structural cracks in the corner of the piece where one section of the wall connects to another, the crack is only set to expand once the piece has been fired.
If something does pop up during your clay’s final firing process, you might have a great chance at fixing the same in its bisque stage. When repairing a clay piece in the bone dry stage, adding wet slip, water, or very wet clay could be a big mistake.
In the process of fixing the cracks in the bone dry stage, scoring is an important part of the process. If you fail to do so, the crack might start to deepen further. Create some roughness & stickiness in the cracks to allow the clay piece to stick. Make sure you smooth out the surface before it is fired. If the surface seems uneven, repeat this process as many times as necessary.