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How I finish thrown pots


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#1 Hermes

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Posted 06 January 2013 - 09:14 AM

How I finish thrown pots
The title has the intention to emphasize on how I finish pots. Perhaps it implies that not all what is described follows the orthodoxy of common knowledge.

Throwing

Since I leave the thrown pot on the bat for drying, I need a lot of bats.
Advantages:
· No risk of deformation or finger marks like can occur while cutting with a wire.

· When almost leather-hard, the pot can be trimmed while still firmly fixed on the bat.

· When leather-hard, the pot releases by itself and the bottom is still moist enough for further trimming.

Disadvantages:
· There is a very slight risk of cracking of the bottom. In my experience, I very rarely had that problem: only with extremely thin bottoms.

· The drying occurs from top to bottom, whereas in the wire-cutting, the drying is more uniform. In my experience, it never caused a problem.

I made bats from very durable. resin impregnated plywood used for concrete casting. This type of plywood can easily be found in DIY stores.
My wheel is designed to accept notched bats. My bats are cut out using a jig-saw and a standard panel provides many bats. A corresponding notch is filed out to secure the bat on the wheel.

Drying

My drying shelves are wall mounted. This is not ideal as the air-circulation at the room side is different than at the wall side and thus, the pot may dry unevenly. To remediate that, I regularly give the bat (with pot) a quarter of a turn. Movable drying racks are preferable, but my studio is small.

Trimming

As mentioned, I sometimes trim the pot on the bat in the early leather-hard stage. But, where possible, I finish the wet pot just after throwing by removing the slip layer with a flexible rubber or thin stainless-steel rib. When I do it with care, I get an excellent finish making further trimming unnecessary.
For the bottom part however, I pay special attention.
Once it is releases from the bat, I trim the pot. Here I use the Giffin Grip™.
I have different trimming tools, some commercial but several home-made.
I try to keep my trimming tools sharp. I like Tungsten Carbide for trimming tools, but is (very) expensive ( http://www.bisonstudios.com/).
My home made trimming tools are cut out of thin, bluish, blade steel ribbons that are used for securing heavy-duty packaging. The cut-out blade is bent into the desired form and glued into a wooden handle with epoxy glue.
Near to the bottom part of the pot, I often trim a small 'gutter'. This helps to avoid runny glaze dripping on the kiln shelf. For very runny glazes such as crystal glazes, this is not effective.
At the bottom itself, I always trim a recess. This forms a 'bottom ring'. The ring makes my pots be more stable. This detail improves the general 'feel of finish' of the pot. For larger bottoms like large dishes or platters, I leave an 'island' in the middle. This strengthens the platter if excessive force is put on it during its daily use (e.g. cutting food).
I sign my pots with my full name and add an acronym for the clay type and an unique number. The latter is used for the full description of the pot in my database.

Smoothing-up the dry pot

If the pot still shows some unwanted marks, I smooth it with a scouring pad, middle-fine sanding cloth, or steel wool. I often use a Scotch Britescouring pad. It gives good results especially when it is already a bit worn-out. In DIY stores they have pads for wood or metal. I have used both with good results.

Post-bisque finishing (Before glazing)

Sometimes I find bisque fired pots still not smooth enough. Particularly for crystal glazing, the smoother the pot the better the results. I also use it to obtain an egg-shell finish. When I use grog free clay, I use fine waterproof sanding paper in water where I have added a drop of dish-washing detergent. Of course, I let the pot dry thoroughly before applying the glaze.

My pages on Ceramics can be found at:

http://users.telenet...amics menu.html



#2 Jime

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Posted 06 January 2013 - 11:38 AM

these are great ideas, thanks for taking the time to share them!




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