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yesterday I made a vase (shape is like a regular mug without handle) using regular clay. It was my first pottery attempt.

I made it using two slabs, one circular for the base and one rectangle rolled for the body.

as I was working on attaching and smoothing, the bottom stuck to the board and I used a wire to detach it but it didn't cut perfectly and a slice of the base stayed on the board, like 1mm. however both slabs were 4~5mm thick initially.

for now I've put it in a plastic bag and sealed it. so it should stay wet.

Can I make another circle and attach it to the base (by scratching and wetting both)? or will it break in drying and firing?

anything else suggested?

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  • 2
    I don't work with regular clay, so just some thinking out loud. 1. If the base still has a 3-4mm thickness, might that be enough so you don't need to add more thickness? 2. You successfully attached the body to the base and closed the loop on the body. Is there a reason you think adding a layer to the base wouldn't work? 3. Just going from theory, it ought to bond if you get the surfaces to merge. In addition to scratching and wetting both surfaces and allowing them time to soften, a thin layer of thick slip between them should act like glue when you press the surfaces together. (cont'd)
    – fixer1234
    Oct 12, 2022 at 23:28
  • Then blending the edge would minimize the risk of the layer peeling off. And handle it in a way where gravity isn't trying to pull the layer off the bottom (e.g., don't hold it by the sides without supporting the bottom, don't let the new layer stick to a surface that will tug on it when you move it, maybe keep it upside-down if the base is strong enough not to sag, or support it on the inside, etc.). 4. Since it is still soft clay, you could consider the mishap part of the learning process and remake the vase if you're concerned adding a layer could fail. (cont'd)
    – fixer1234
    Oct 12, 2022 at 23:29
  • But hopefully, someone who works with clay can provide better advice on what's known to work. :-)
    – fixer1234
    Oct 12, 2022 at 23:29
  • @fixer1234 tysm, as I said it's my first attempt so don't know how will it behave, (they could shrink differently, air may trap in between, etc) however, the base seems too thin, as I put it upside-down it sages a little at the center, and also I like to have an operational thing, at least it should support some weight. but again, if I add, hardly could maintain base and body thickness the same, so again there's more chance of cracking, but as it is, it can both crack and will be weak if it doesn't.
    – user174174
    Oct 13, 2022 at 2:14
  • p.s. yes I hope someone answers this question before it gets too late!
    – user174174
    Oct 13, 2022 at 2:25

2 Answers 2

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Disclaimer: I have very little practical experience with clay.

It will probably be easier and more practical to remove the current bottom entirely and replace it with an undamaged one.

The main reason is that if the bottom already droops now, you'll have a really hard time reinforcing the bottom without accidentally destroying the entire vase. To create a strong bond you have to kind of massage the new clay into the existing one, otherwise the bond is prone to cracking during the drying or firing phase. That means supporting the damaged bottom from the inside of the vase without accidentally damaging even more of it.

It will be easier to create a strong bond around the rim of the new bottom than over the entire surface of the old one. You can even give the existing walls of the vase some additional drying time (but not too dry!) to make them more resilient against bending and drooping.

And since you already know that the bottom likes to stick to the surface, intentionally make your new bottom thicker and then cut it to the desired thickness when you cut the vase from the table. You can also leave the bottom a bit thicker than desired and then cut it to it's intended thickness after some drying time. I suggest watching some videos of people forming clay dishes to see this precise shaping of a half-dry object. It's far easier than trying to give very wet and malleable clay it's final shape and then getting it to keep that shape without deforming.

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  • Smart solution!
    – fixer1234
    Oct 13, 2022 at 16:50
  • tysm for the answer, I tried but the joint was too strong, I had attach it from outside by pinching and from the inside using a coil, so removing was deforming everything. But indeed it should be a good solution, I just have to wait for it to dry more. And btw, won't the difference of water ratios in semi hard body and new base cause difference in shrinking ratios? or is it negligible?
    – user174174
    Oct 14, 2022 at 3:01
  • @user174174 You'll have to wet the bottom edge of the side walls again to bond them with the new bottom, but the rest of the side walls should be more stable. As mentioned above I don't have enough practical experience to say if that will lead to problems while firing. Maybe covering the vase very loosely while drying can even out the water content?
    – Elmy
    Oct 14, 2022 at 6:11
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One of the most annoying things about clay, is the difficulty in joining it!

Tips

  • Lightly spray your item in drier areas to create uniform dampness and/or
  • Unwrap damper parts so they dry slightly to be the same dampness as other parts (watch over it!)

To join a piece on:

  • Score the base of your item
  • Apply clay slurry (clay mixed with water to form a thick paint like consistency)
  • Add the extra piece you want to apply and smooth it on to fully attach

TIP

Any air bubbles between new piece and base, will expand during firing, which can disastrously cause your item to:

  • split
  • break
  • even, explode

So try to avoid air bubbles.

Experience (mine) A level Pottery, grade B, UK. Lifelong artist

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  • Thank you for sharing this. So you also recommend me to totaly replace the base?
    – user174174
    Oct 15, 2022 at 5:45
  • No, I described how to stick an extra layer on the base. I wouldn't attempt to replace the whole base, no.
    – user3025
    Oct 15, 2022 at 11:27
  • Also, don't get too hung up on this one - go on and make another item. Where is your pottery teacher by the way? It would be best if they could help/show you. Also as an exploding pot in a kiln can destroy other people's work, it's good to let the kiln organiser know.
    – user3025
    Oct 15, 2022 at 11:31
  • sorry for misunderstanding. by the way I don't have a teacher that's why I asked my question here! for now I only have access to the web and tuts on youtube. also there's no kiln organizer or other people's work as I plan to fire it myself.
    – user174174
    Oct 15, 2022 at 12:30
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    Wouldn't adding a large footprint layer have a high likelihood of trapping air, and be difficult to blend the surfaces?
    – fixer1234
    Oct 15, 2022 at 14:32

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