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Biglou13

Plaster Batt/slab For Wedging And Drying

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i dont have the room for dedicated plaster slab.

what have you used as mold?

if concave waht did use use to mold that?

 

sure the go to is gcottle boards just looking for what innovative ideas have been used.

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to prevent the above leakage, line the joints where the cottle boards meet the plane with a coil.I woul kip h plastic bag cause I will cheat a wrinkled surface. I cast on plexiglass fo a smooth surface. tap he able as he pleaser is Setting up so he air bubbles rise o he top surface, spray he plaster with diluted alcohol before and after pouring the plaster.This breaks he surface tension an he bubbles disappear leaving a smooth surface on top.

marcia

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What do you guys add fiber wise to stiffen a large plaster form?

I think I found mold at at ag/feed store.

It's 20+inch at widest and I think I'll reinforce with some kind of fiber what do you use?

Where do u get nylon fiber?

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I like a really thick slab-

My fellow potter used the 1/4 inch mesh of fruit plastic bags to keep thinner slabs together.

The thing is once it cracks its no fun to use-so I suggest thicker on a solid non flexing base.

My plaster slabs are over 4 inches thick and never have cracked in 40 years-I think it was casting plaster not pottery#1 back then.

If you use mesh use plastic as it will not rust or hurt you.

Mark

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I made the top of myplaster wedging table from a sheet metal industrial shelf turned upside down.  You have to put a little masking tape in the corners and any holes to keep the plaster from flowing out. The steel shelf adds a great deal of strength and rigidity so we can move it without fear of damaging iy. You can set it on a table when you use it then pick it up and set it on its edge when you need to save space. You can often get these shelves quite cheap used in a wide selection of sizes from industrial shelf suppliers.

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A friend used an old dresser drawer. I use a shallow plastic tote, poured full. I keep in the tote unless it gets really damp and then I sit it out for a while to dry. Because of the smooth plastic bottom, the slab is very slick and comes out easily. The same process, purposely wetted , makes a damp box for holding leather hard pieces.

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I don't use fiber in plaster for slabs. I have three large slabs I use for drying slop and appear clay. the slabs are about 2.5- 3 inches thick.

2' x 3' rectangle.i cover them to protect the surface if I need the space for other activities???like glazing! assembling or drying pots. my wedging table is a little thicker and stands on 4"x4" legs with a cutting wire on one side and next to my wheel. I throw any wet clay from throwing and wedge it up when it is ready.

Marcia

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I have taken the same direction as Marcia.. .no longer using fiber in my slabs.  With limited space, my wedging slab is roughly 2'W x 2'L x 2"H and was poured on a countertop laminate surface so that the top of the slab would be smooth.  At this size, I can still tilt it up and out of the way when/if countertop space is needed.

 

I do have some forms that I have used for many years that include natural wood, excelsior packaging material.  Back in the late 60's (when I first enrolled in a clay class) this was a common practice for building plaster bats.  You can still get the excelsior in small quantities... I think the last time I purchased some it came from Uline.  Back in those days, there was some research that indicated the coefficient of expansion for plaster and excelsior matched closely, thus its use for structural stability.

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