Chilly

Try it. Nothing to lose, expect that might come out worse. Probably quicker to make another one.

Hi @Fuller Welcome to the forum. I'm just south of you, in Essex, potting in a greenhouse, so have the same problems getting anything to dry and not freeze. I don't have any heating in there at all. I bring stuff indoors at this time of year, actually do the same in hot weather. I have a shelf over the bath, for drying pots. I tend not to do much clay this time of year. This week the bath shelf is hosting dyed wool! It's worth finding a shelf or space inside if you possibly can.

Are you sure?

The longer you work with clay and firing, the more you will understand that cones are king. If you've ever done any cake making: Imagine putting a fruit cake into a cold oven, and taking it out again when the oven gets to the correct temperature. DegC = OK, cake = not OK. Cake and clay both need heatwork. An amount of heat for an amount of time. Cones measure both. Buy some cones and put them in your next firing. Set 3 cones on every shelf. 1 cone for the temperature you're aiming for, 1 next hotter, 1 next lower. And beware that the numbers start at 022, going up 021/020/019

http://www.ccpottery.com/

Slip-casting plates will be incredibly slow. As @Callie Beller Diesel says, commercially they are made with jigger/jolley. If you had, say, 6 slip-casting moulds, at the best you could cast 6 plates per day. With one jigger/jolley mould, you would be able to re-use the mould multiple times per day. Slip-casting moulds have a finite life-span - around 30-40 casts (from memory) casts before the plaster starts to deteriorate. The jigger/jolley moulds will allast much longer as they do not come into contact with an ingredient included in slip.

I don't think the cat will come out very clean

I think I could spend more time making tests than real pots. Remember to make vertical tiles, or something that closely resembles the real pots. Flat test tiles are not good representatives if you're going to make tall vases!

Go back to the supplier. If processes haven't changed, must be source materials.

They might work, might not. Might end up over-fired and run off the pots. Only way to know is to test. Put cookies under to protect your shelves.

You may think it's for decoration, but there is no knowing what a future owner will do with something that looks like a bowl. Just saying

You can also use the flat part of a fingernail to smooth off the rims, if you don't have a rib. You get a good "feel" and can make sure there are no gritty bits on the surface.

On a computer: On a phone, tap the three lines, then Account, then Profile, then the pencil in the grey box near the top of the screen. Scroll down to Location.

Make sure the kiln tech knows you are using a ^5/6 glaze and that your post needs to stay on it's cookie to protect the kiln shelf.

Plus 1 to everything above, and....... Take careful notes. Buy a gram scale and weigh/measure carefully, so when you produce the perfect pot, you can re-create it !