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Week 1 of Slip ‘n’ Surfaces

I am teaching a 4 week class this June called Slip ‘n’ Surfaces.

I have a lovely group of students and I’m really excited about teaching surface decorating techniques.

This first class we started out discussing slips. What is slip exactly?

The slip at Lill and in many places is simply liquid porcelain with pigment in it. Here we use Mason stains which are very dependable. The key to using slip well is to understand its properties. Because it is clay, it will not run or flux as glaze does and so you get great sharp details and precision but it does shrink as it dries. So you must apply it in time for it to bond to the surface of your clay and for them to shrink together.  You have a a much bigger window of opportunity when applying slip to porcelain than to stoneware because porcelain and stoneware have different rates of shrinkage.

I gave a demo of my favorite texture and color technique- what I call the Eric Jensen technique- I’ve posted about it before so I will be very brief in this description:

Start with a thick pad of clay- at least an inch thick, spread slip on it and then “dry out” the slip with sheets of newspaper.

Once the slip is “dry” (you can touch it without it sticking to your hand- it’s a kind of a leather feel to it) then you can add a second slip or stamp it or even draw in it. If you add more slip, you must dry it out again and then you can begin to throw the slab out.You can put two colors down with out drying in between but they lose their definition and blend as above.

The key to this stage is that you must keep the slip side up while you are throwing the slab. Because you’ve dried the slip, it will break up instead of stretching with the clay  and you get a great texture. If you’ve incised lines in it, the surface tends to break along those lines.the line around the perimeter of this slab was made with a spiky wheel normally used for patterns in sewing.

Then I took that piece and put it in a mold or “drop mold” so named because to settle the clay into it, you drop it once or more.

This is a different slab and you can see it tore where the clay was uneven or had air bubbles.

To adapt to the shape of the slab, I took some extra clay and built up part of the mold. Next week I’ll put little legs on this tray.

Next I demonstrated painting and sponging on slip by doing some of these summer trees. A sponge with a rough surface is excellent to get the slip applied so it emulates the transparency and distribution of leaves.

I then go in and clean up the trees with a stick and loop tools as I have more control with those than the brush or sponge.

This is almost the finished product.

Lastly, I did a brief demonstration of what I do the most, cover the surface with black slip, draw an image with a nice wooden stylus you can see some of my sticks in the upper left(you can see some of my sticks in the upper left)

and then carve away negative spaces with a fine loop tool.(and here you can see some of my fine loop tools)

Today I went back to my leather hard pieces and used a sure form to finish the edges. This is a tool often used for plaster and can be found in most hardware stores.It’s a very handy tool!

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Slip ‘n’ Surfaces Week 4

It’s been a great class with really wonderful students. I’m always so thrilled to see what they are working on each week. Since this was the last week, I reall packed in the demonstrations.

Banding

I started off by throwing a bowl with about 3 pounds of clay. People wanted a refresher in how to throw a larger bowl. This was a good item to demonstrate banding with slip  while it was still on the wheel. One of the most common and annoying problems with banding is that the slip doesn’t just glide on there in a steady stream leaving a perfect highway of color on your pot. Especially if you are applying it to a leather surface, the clay can suck up the moisture from a thicker slip and give you a very uneven, often kind-of pitted surface.  If you are applying to leather hard it helps to spritz it with a bit of water ; wait a few seconds for the water to sink in a little, otherwise you lay your slip down onto a thin layer of water and it can drip and not stick well.

If you are applying to a freshly thrown pots (which is ideal for bonding for porcelain slip bonding to stoneware) you still have to dip the brush more frequently than you’d think. Just keep the wheel going steadily and hold your hand steady too. You can always clean up the edges with a metal rib or stick tool. Here I used my rib to put a little wavy edge on my band.

Leaf Stencils

Next I threw a low terra cotta bowl so we could do some stencils using leaves. I also showed how you can take something like a fork and with an even motion while the wheel is going slowly, make another kind of border around the rim- this time on the inside. 

I had  some problem getting the leaves to really lay flat but Kristina solved that problem by using some newsprint to really presss her leaves down flat.

Here is the plate after she pulled the leaves off

Beautiful. She will go back in when the slip is leather hard and clean up any places the slip snuck under the leaves.

Jennifer put some on the outside of her mugs which also turned out great. It’s important to think about how the leaves will fill the space. I think all these examples (except mine) are excellent.

Marbelizing

Another thing you can do with two or more colors of slip is to marbelize- like the fancy paper you often see. I think for this you need a fairly flat, contained surface. I had a small stoneware plate  which I poured some blue slip into and then dotted and trailed green on top of that in a fairly random pattern. then I dragged a very pointy brush (you could use a feather or pointy stick too) through the dots.  I was inspired by plant forms.

When I trim the plate, I’ll go in and clean up the edge of the inside too.

The one thing to be careful of when marbelizing is that it adds a LOT of moisture to your pot. Make sure your form is supported or dry enough to absorb that moisture and keep its shape.

Etching

Then I did my surprise demo. This was “etched” clay. Really, I would only recommend this technique for porcelain as you will soon see why. I threw a tumbler and set it to dry. When it was hard leather dry, I painted a pattern on it in wax. After the wax was completely dry (and you can do this technique with varnish was well)  I began wiping at the surface with a wet sponge. The wax protects the surface beneath it but the surrounding surface is removed. If this was stoneware, it would just be horribly gritty.

After a few wipes, I decided to scratch into my wax a little to get a more detailed resist area. 

This will look great with a breaking glaze like Shino, Celadon or even Josh Green.

Kelly took this idea and ran with it – here is her process: and she got the brilliant idea of inlaying black slip into the wiped away areas. She painted it on and the wax resisted it over the raised areas. She sponged away all non-adhering slip and here is the resultDoesn’t that look cool?

Another variation on this idea is to paint your entire surface with slip, then a pattern over it in wax and then when you wipe away, you leave the color where the wax protects it and the color is removed everywhere else. Kristina suggested this and I can’t wait to try it!