Two Piece Vase tips?

[Brandon Franks]

Any tips for two piece vases with porcelain?

 

My method is to throw the bottom of the pieces the day before, let them get to leather hard, then throw a top on. I have only done it with heavily grogged stoneware. I plan on using some vinegar around the connection spot. This method allows for maximum control of the top portion, but with leather hard porcelain, god knows what can (and probably will) go wrong.

*this is the method Matthew Kelly  uses if any of you are familiar*

I think if I dry them well enough they should be fine, right?

 

 

 

 

[liambesaw]

I throw both at the same time since by the time it's dried it'll be shrunk down.

I throw both pieces, then set them down in front of the buddy heater or heat gun or torch, and get them so they're no longer leaving finger prints and then invert one on the other.  

I do this with stoneware too, but I don't see why it wouldn't work with porcelain.

Here's a short video of the process I use for moon style jars: 

 

[Brandon Franks]

24 minutes ago, liambesaw said:

I throw both at the same time since by the time it's dried it'll be shrunk down.

I throw both pieces, then set them down in front of the buddy heater or heat gun or torch, and get them so they're no longer leaving finger prints and then invert one on the other.  

I do this with stoneware too, but I don't see why it wouldn't work with porcelain.

Here's a short video of the process I use for moon style jars: 

 

I am aware of this method and quite like it (when it worked for me). My problem was always  keeping it in control. I always found that when the piece was unevenly dry from the outside compared to the inside, its promoted my pieces to collapse. 

 

I know it works well for many people, but I never really found my sweet spot with it.

[oldlady]

try a trick i saw a potter do once.   he put a groove into the bottom half and a pointed rim on the top piece.  they fit together easily and he was making huge vases, 30 inches high, 12 wide.    it seems to be a matter of keeping both halves the same dryness, liam drying out the clay to make it even works for him.

[Brandon Franks]

8 hours ago, oldlady said:

try a trick i saw a potter do once.   he put a groove into the bottom half and a pointed rim on the top piece.  they fit together easily and he was making huge vases, 30 inches high, 12 wide.    it seems to be a matter of keeping both halves the same dryness, liam drying out the clay to make it even works for him.

The largest two pieces I do are 20 inchers thrown - about 17 or 18 or so when fired to cone 10. I make the top of the second piece completely flat and 3/4 of an inch thick at the rim (attachment point), then throw that overhang into the leather hard piece of the vase.

These above are from today, you can see where the joint is if you look close, just need to be trimmed up and burnished and they will be looking pretty good.

 

Im just praying these don't crack.

[liambesaw]

If you're throwing one part one day and the other part the other day, it'll have a harder time not cracking as the top half shrinks.  That's why I throw them at the same time and then torch them a bit to firm them up, to keep that shrinkage as similar as possible.

[Mark C.]

Throwing them both same day is way better for cracking-Liambesaw is dead on .No reason to wait another day.With clay the same moisture content is always the best practice .

In your heart you know this.

[neilestrick]

There are two main problems when throwing larger pieces: Centering a big piece of clay, and getting all the clay pulled up from the bottom without getting the top too thin or wonky. So the problems are solved by doing it in two pieces. However you don't have to let the bottom firm up before joining, because that causes other problems. When I need to have invisible joints, I throw two cylinders, on bats, leaving them thick. One is the bottom and has a base, one is the top and is an open cylinder. Then I stack them  right away and give them one or two pulls to join them well and thin them out, and then shape the form. The bulk of the pulling is already done, so the pulling is pretty easy. I do not score the joint, I just make sure the rims are flat and dry so the pieces stick well (I use a metal rib to flatten and scrape off the rim). Pulling through the joint joins them perfectly. If you score, you may get little air bubbles in the joint.

[Mark C.]

When I made big pots which was some time ago as I used to have a few in the booth always . Not anymore-for me the 2008 crash killed that and I just never looked back when small stuff was king in that downturn-hey folkss what another downturn? time for small stuff.

Any way this 24 inch vase was from those days as its a second that I kept from death and have used it for outside florals-I took this shot this am from next to our front door .

I think it was two piece but back then I made two and three piece as well as slab bottom thrown tops large pots. porcelain does not like to go that big so WSO clay with porcelain slip or even stoneware with porcelain slip for great glaze colors.This pots hols water just has some really large pitted areas . Hold plants fine for us just not for resale.I think its about 20 years old now.

All pieces thrown in same day.