Can I add more clay to an object for reinforcement?

Question

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?

Answer 1

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.

Answer 2

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