[TheChrysalisCloset]

So I made a wedging table with a built-in cutting wire etc. The plaster is over 5 in thick and has set and dried for months. One huge problem though. I tried recycling thrown clay scraps and after it dried to the right point I started wedging and found that the clay started pulling up small pieces of the plaster surface, which obliously made the clay unusable, or at least unfireable. What can I do to fix the table with out pulling up All the plaster?

[bptakoma]

TheChrysalisCloset, on 10 June 2010 - 06:13 PM, said:

So I made a wedging table with a built-in cutting wire etc. The plaster is over 5 in thick and has set and dried for months. One huge problem though. I tried recycling thrown clay scraps and after it dried to the right point I started wedging and found that the clay started pulling up small pieces of the plaster surface, which obliously made the clay unusable, or at least unfireable. What can I do to fix the table with out pulling up All the plaster?

Cover the plaster surface with canvas -- that's the easiest immediate solution.

[Slipped]

I appreciate this question, as I am getting ready to make my own wedging table for my "new" home studio and had the same fear. Is there a particular brand of plaster that's reccommended for a wedging table, and how thick should it be? (I had planned on about 3 - 4 inches) Great timing!

[Ginametrical]

Slipped - I would buy the Georgia Pacific Pottery Plaster. I am in the process of making my own wedging table and this is the plaster I will be purchasing. Bailey's website has the plaster in 100lb bags for $26.00. I am also planning for a thickness of 3in - 4in.

Here is the description of the plaster from baileypottery.com:
Plaster, Pottery (Georgia Pacific K-59) — The standard of the industry, equivalent to No. 1 Pottery Plaster. Recommended for most slip casting applications for strong, long-lasting molds.

[hansen]

something went wrong - either the type of plaster or the mixture itself. I'd say (1) use the canvas and (2) try to get it right so you can teach others. I use the concrete floor or concrete pavers 18" x 18" mounted on the wheel head. I used to use a piece of slate which was 1/3 of a pool table. It did not dry my clay. Suppose you want to wedge clay before throwing and it is already dry enough? The drying action of the plaster would not be welcome. Clay will dry in air, which is free. Why spend money on plaster?
h a n s e n

TheChrysalisCloset, on 10 June 2010 - 05:13 PM, said:

So I made a wedging table with a built-in cutting wire etc. The plaster is over 5 in thick and has set and dried for months. One huge problem though. I tried recycling thrown clay scraps and after it dried to the right point I started wedging and found that the clay started pulling up small pieces of the plaster surface, which obliously made the clay unusable, or at least unfireable. What can I do to fix the table with out pulling up All the plaster?

[Ginametrical]

Hansen - How do you recycle your clay without plaster? I am interested since I have about 700lbs in big dried blocks of clay that I bought 'dirt' cheap and am looking to reclaim. I'm open to suggestions other than a plaster top table.

I feel like letting the slop just sit and air dry would not promote even drying... the plaster gives me a good consistency in just one day, flipping it over half way through.


Love all of the imput!!

[hansen]

Ginametrical: First crush the clay with a hammer and let it get really dry. This won't work with porcelain tho. Right. Then submerge in large amount of water. Say, make 20 lbs. at a time unless you have special equipment. Get a blunging attachment from your pottery supply place for an electric drill. When the clay is completely slaked and melted, use the drill to mix evenly. Okay you can screen for foreign objects maybe 10 mesh at this stage if you want. Let this set in the bucket a few days. Pour off all the excess water. Now relocate to a cement mixing pan or trough. Mix dry clay - xx sagger for salt fire, hawthorn for cone 10 stone ware or gold art for cone 6 stoneware, or red art for cone 2 earthenware, mix with a trinagular tipped trowel. Or use clay mixer machine. THEN BAG THE CLAY. Let it mature for at least a week. It will stiil be just a bit to wet to throw but will be ready for setting out for the final exposure for dewatering by air. It is all on my blog site
americanpotter.blogspot.com
-h-

Ginametrical, on 17 June 2010 - 11:31 AM, said:

Hansen - How do you recycle your clay without plaster? I am interested since I have about 700lbs in big dried blocks of clay that I bought 'dirt' cheap and am looking to reclaim. I'm open to suggestions other than a plaster top table.

I feel like letting the slop just sit and air dry would not promote even drying... the plaster gives me a good consistency in just one day, flipping it over half way through.


Love all of the imput!!

[Dee Sota]

Slipped, on 11 June 2010 - 09:46 AM, said:

I appreciate this question, as I am getting ready to make my own wedging table for my "new" home studio and had the same fear. Is there a particular brand of plaster that's reccommended for a wedging table, and how thick should it be? (I had planned on about 3 - 4 inches) Great timing!

My husband made me one. I only use if for drying my overly wet collapsed clay ( I am a beginner), it does not work for wedging, if picks up stuff. The plaster form is 4 inches thick, 24" x 20" , it took almost two bags of plaster and it took many days to dry. (As I use it, I find that it is too big and too heavy) In the middle of the frame and before he poured the plaster, he connected hog wire to the frame for stability. I have another table that was made to wedge on. This table is covered by canvas (purchased at clay dealer) works perfect for wedging. Hope this helps, Dee

[sandy miller]

Go to Home Depot and get a piece of dry lock board, not cement board it's too heavy and flakes a bit. But the stuff that is thin and fiber Duralock I think is the name.

cut it to the size of your wedging table and screw it down to your wedging table (over the plaster) It wipes up with a sponge, scrape it down with a plastic putty knife.

[Eric Opoku]

TheChrysalisCloset, on 10 June 2010 - 11:13 PM, said:

So I made a wedging table with a built-in cutting wire etc. The plaster is over 5 in thick and has set and dried for months. One huge problem though. I tried recycling thrown clay scraps and after it dried to the right point I started wedging and found that the clay started pulling up small pieces of the plaster surface, which obliously made the clay unusable, or at least unfireable. What can I do to fix the table with out pulling up All the plaster?

There is no other way to get this problem solved except to get seperate tables for your plaster work and another for wedging clay. Clay and plaster do not 'mix' at all.

[Sherman]

Just a note to point out that I've changed the title of this topic from "In the Studio" to "Home Made Wedging Table." This will make it easier for folks to find, since it's already in the forum "In the Studio."



Sherman

[Brandee Ross]

I use HardieBacker board for reclaiming clay: http://www.jameshard...arterInch.shtml It's thin and light, which means I can store it out of the way when it's not in use.

I wedge clay on a table topped with smooth, untreated oak plywood. It has held up really well and I don't have to worry about plaster getting into the kiln.

[hansen]

I found out that with the 11$ cement mixing pan from home depot i could foot wedge 100 lbs of clay about as fast as a clay mixer can. So for example if you have blunged, slaked, allowed to settle, and poured off water, you can get about half the way there. Then add dry clay & grog or sand and foot wedge until it's done. like Cedar Heights Bond Clay, Gold Art for cone 6 or Hawthorn Bond Clay for cone 10 - there are other options. Then bag it for about a week or two.

If you want really consitsent, then wrap the too-moist clay in cloth and rig it up suspended by a rope - amazing, the cloth draws the moisture out of the clay and yet keeps the surface damp.

Ginametrical, on 17 June 2010 - 11:31 AM, said:

Hansen - How do you recycle your clay without plaster? I am interested since I have about 700lbs in big dried blocks of clay that I bought 'dirt' cheap and am looking to reclaim. I'm open to suggestions other than a plaster top table.

I feel like letting the slop just sit and air dry would not promote even drying... the plaster gives me a good consistency in just one day, flipping it over half way through.


Love all of the imput!!

[Lucille Oka]

TheChrysalisCloset, on 10 June 2010 - 02:13 PM, said:

So I made a wedging table with a built-in cutting wire etc. The plaster is over 5 in thick and has set and dried for months. One huge problem though. I tried recycling thrown clay scraps and after it dried to the right point I started wedging and found that the clay started pulling up small pieces of the plaster surface, which obliously made the clay unusable, or at least unfireable. What can I do to fix the table with out pulling up All the plaster?

About plaster wedging tables-

Sorry my reply is so late into the dilemma but hope this helps. First, not all plasters are the same. They require specific water to plaster ratio formulations for particular consistency and molding dimensions.

There are several possible reasons that could be the cause for your problem: 1. the wrong plaster, 2. the wrong plaster water ratio, 3. improper mixing, and 4. improper curing or drying. These and other things such as additions to the mix and I am sure a host of other things can cause this problem.

Plasters from home building supply stores are too soft and cannot withstand the work that we will do to them. Building suppliers' plasters are used for applying to walls and upon drying they take a coat of paint. That's it for them.

When purchasing plaster for Ceramic use it is far better to get your plaster from a ceramic supply store, but before you do that, Google US Gypsum. Go to their website. There you will find a wealth of information about the different kinds of plasters and how to mix and cure them. (Many of the ceramic suppliers also have in their catalogs details of the different plasters they carry.) You will also find at the US Gypsum site, a little gem of a thing called a 'plaster water ratio calculator' to help you determine how much of each you will need.

If you have not used the right plaster, I would GET the right plaster, enough for at least a two to three inch addition or more to the top of your ruined plaster tabletop. Wet the entire surface of the tabletop. Wearing a face mask, using protective eye wear and protective gloves, deeply gouge out using chisels and/or plaster tools, etc., the entire surface all the way to the edges and down, unevenly. Keep it rough, gouge out about an inch deep. I mean really gouge out the surface at an angle and away from you, so that the new surface will ‘lock’ into place. Be careful the tools are sharp. Clean out any bits of plaster that you have removed, rewet the tabletop.

You will need to set up (and every studio should have at least one) a prepared (soaped and sealed) 'cottle box' around the gouged tabletop so that it can provide the added height. Be sure to have newspapers on the floor to catch excess plaster.

CORRECTLY MIX the 'RIGHT PLASTER'. POUR steadily down the side of the cottle box the new plaster mix, on top of your wetted, gouged surface. Be sure to fill in all of the gouged areas. Pour and fill up the 'cottle'. After you reach the height that you want, you can 'screed' off the plaster excess with a long flat stick.

Before the plaster has fully set, but before it gets hot, using your WET rubber gloved hands, smooth and press this new surface again all the way to the edges, keeping the surface as flat as you can. Using plaster tools or a 'hand screed' can help. (It is like a squeegee but has a metal rib on the edge). Let the plaster tabletop fully set it will get hot, leave it until it turns cool all over, then remove the cottle.

Clean up the new plaster tabletop, eliminate all sharp edges. You need to do this while it is still wet. Do not wait for it to dry. You can use scraping tools on the sides wiping with a CLEAN damp rag. Prop the new surfaced tabletop on small blocks. This maybe a little difficult but you can use shims to get it started, engage the help of another person if needed. Air needs to circulate all around the plaster tabletop. US Gypsum will tell you the temperature that you will need for the curing. Next day, prop the other side of the table top. Continue daily alternately propping sides so that the plaster dries properly. Don't rush it by increasing the heat. Just continue propping. If it is a square shape you can prop different sides. Don't make the props too high or the tabletop may slide off the surface. Do not throw your excess plaster down the drain put it in the trash. Use the ‘ruin clay’ for making models for casting, label it as such. I hope this helps