Category: surface decoration

We had a delightful sgraffito workshop Sunday, October 11, at Lill.

 

I started with the basic question of what is slip?

In its simplest form, slip is clay that has had water added to it, possibly pigment and been sieved to make it very smooth. At Lill, we use Grolleg porcelain and Mason stains for colorant.

 

I talked about application. 

It is key to understand how slip works – a wrong application will just come off your pot. 

Because slip is CLAY, it shrinks.  That means you can not put it on a bone dry pot. Your slip will shrink as it dries and simply flake off. 

 

Because it is Porcelain, it shrinks at a slightly different rate than stoneware and therefore when you apply it to stoneware, you have to be more careful that it bonds to the surface or again, it will come off- sometimes even after the glaze firing.

Here is an example of Porcelain on porcelain- THICK and I know (because I watched her) that this was put on with a frosting bag onto leather hard porcelain. This is a photo of the bisked piece- it made it through the drying and firing process without coming off:

 

So while it is pretty easy and forgiving to put a porcelain slip onto porcelain pots,

I have a couple of tips for applying it to stoneware.

 

First of all, the more “wet” your stoneware, the better – although the other end of that spectrum is, that your pot will absorb some of the liquid from the slip and could, conceivably, collapse from absorbing too much moisture.

That is the beauty of the slump mold- it can just lie there, bonding while it dries.

You can see it’s white slip over stoneware if you look at the edge.

It also helps to put it on thinly

and lastly, it helps to burnish it on to further bond it with the surface of your pot. You can do that when the surface is leather hard.

 

What I do for application is fairly ideal; I put the slip on my porcelain pots after they are leather hard and I’ve trimmed them.

I then “carve” (or sgraffito) them while they are still leather hard.

This also reduces my chances of breathing in a lot of clay dust as my shavings are still wet. 

Because those shavings dry quickly and then they do become dusty, I then dump them in a little cup or bowl of water to keep them out of my lungs!

 

Now that the pots were ready,  I started in on the fun stuff.

Basic sgraffito is just scratching through slip. that’s what I did for this rabbit plate.Here is an example of the same technique (and her inspiration!) by one of the students. This is slip over Terra Cotta.

Isn’t that cool?

 

Here are two more examples from the shelves of Lill- these are both with a dark slip and white of the porcelain showing through- quite the reverse!

 

The next type of sgraffito  uses the negative space to make the picture: in this case an octopus.

There are several ways to do this- one is to rough in the basic design without covering the entire pot with slip. This has the advantage of saving time and guiding your design but it can be limiting in that you have to stick with the lines you painted on.

And then after carving:

If you cover the entire piece with slip, it becomes a blank slate upon which, you can draw anything. If I don’t know what I’m going to draw ahead of time, I will paint the whole thing and look for inspiration in the patterns and textures of the slip when it’s on the pot.

Layered slip  gives you some interesting lines qualities- in this case I started with white over stoneware.  Once that was bonded and the piece leather-hard, I put on a layer of black, waited for that to stop being shiny and added a layer of aqua.

I drew fish with simple lines.

Here is the tray with layered slip (blue over green over white on stoneware) I did from the last workshop. It is glazed in Celadon.

Inlaid slip  is the complete reverse of the technique I used to draw the rabbit. There are several helpful things to know when you are inlaying slip. It is probably more important to make your lines deep than wide since you will be scraping off a thin layer of the pot, a shallow line can disappear.  The drier the slip and the pot, the cleaner the line will appear when you are scraping. This is what a partially scraped inlaid piece looks like (black and a little blue in porcelain)

Here is an example of Jeanne’s. Here is the tray in inlaid for the last workshop. It is glazed in Shaner clear mixed with Temoku.

 

Here are a couple more examples of (really great) student work!Seeing this last example reminds me to tell you that:

A.. this technique is great for a delicate and intricate design and 

B. CLAY BURRS- these are the bane of any sgraffito-er’s existence. You must have the patience to let them dry before you try to get them off otherwise they will stick back down onto your pot. Usually they dry pretty quickly as they are so small and sticking up, they get a lot of air around them.

Once they are dry, you can easily knock them off with a brush- another caution: DO NOT use a stiff bristled brush or you will scratch your slip surface. I use a makeup brush. These are idea, soft and easy to find – either in a pharmacy or the garbage on moving day!

Week 4 of Slip ‘n’ Surfaces

 

This week we:

Talked about slip application

Didn’t remember to talk about surface preparation (I will now)

Stencils -newspaper resist

Slip transfer – painting onto newspaper

Eric Jensen method reprised with netting

Foot-of-the-week: thrown on foot & pedestal foot

Lip-of-the-week: added coil

Glaze-of-the-week: Shaner White (with a nod to Coleman’s Apple green)

 

Despite this being the last class 🙁     I feel like I gave out a lot of information this week and there seemed to be something for everyone.

I started by talking about slip application as I had come upon something while I was doing my own work that I know about but it’s not often addressed.

I had made a platter  and when I applied the slip, the slip was fairly thick. I show the (unfired) platter here

in contrast to the (bisked) rabbit casserole

which had  a thinner slip application due to the slip being of a thinner, slightly more watery consistency. It’s easier to do finer work with a thinner layer of slip. If you have to draw your lines and do your carving through a 16th of an inch of slip, it is easier to be more clumsy and also to break off little chunks – pointy tips of leaves, etc. You also tend to get more texture when you are carving through a thicker application of slip. It’s hard to see here as I don’t have a good, in-focus photo of the bird platter. 

I then meant to talk just a little about preparing surfaces for slip- I like to eliminate throwing rings with a metal rib when I am throwing and to smooth away the canvas marks with a soft rubber rib when I am handbuilidng. If you are going to put in a drawing or pattern, you don’t need an uneven surface interfering with your image.

Conversely, sometimes a nice layer of slip can hide flaws in a surface.

 

I did again my popular “Birches” demo where I lay down strips of newspaper and paint over them with blue. Karin immediately did a wonderful fern stencil.

Doesn’t that look cool?

 

I took another porcelain tray that was almost too dry to demonstrate newspaper slip transfer. I painted on the paper and then scratched through the dots

 and pressed it onto the surface of the tray. I had little success until I got the tray a bit wetter and the soaked the back of the newspaper  to encourage the slip to migrate onto the clay surface. Then I did it again with black slip.

Actually I did a little more to it so it looks better.

Foot-of-the-week: thrown on foot & pedestal foot

I then reprised the Eric Jensen method but with netting (avocado bag and onion bag) pressed into the slip before the slab is thrown out. Really, I was just trying to make a bowl to throw a foot onto.(also already seen in this blog)  I think it was quite successful.

and then on! to a tiny pedestal foot – I just made a little pinch pot and the foot was a very small ball of clay pressed to make a hemisphere and attached to the pot.

Lip-of-the-week: added coil

For this I made another little pinch pot, rolled a coil and then ran a damp sponge the length of it to smooth it and also to give it more of a “thrown” look.

Scored both the edge of the pot and the underside of the coil and pressed it on for a nice finished look.

 

Glaze-of-the-week: Shaner White

will actually show quite a bit of detail from slip beneath it but dilute the color- making it almost pastel. I found this out one time when I had a completely senior moment and glazed no less than 9 pots in Shaner White instead of Shaner Clear.

Here is the result:mind you, I did still wet my pots down to absorb less glaze as I always do for Shaner’s Clear. Sure, my technique is automatic- I just need to get the right bucket!

Not the end of the world.

We also found this piece on the glaze cart and it shows  slip under Shaner White nicely.

This looks like blue and red iron.

But my favorite thing to do is rub it off the raised surfaces and here is the lovely (if I do say so myself) result on B-Clay of Shaner white dipped and rubbed off over Mazerine Blue Slip. You can see that it’s uneven. Also, the photo makes the clay just a bit more orange than it really is. (Nice photos by Guy Nicol)

Here is another piece found on the glaze cart-  Coleman green over carved black slip. as  you can see it is transparent. But also very

very 

green.

 

 

Student work,

Here is Terry’s foray into wipe away etching. Note how she had a colored slip over the clay and the wax protected it.

Here is Nina’s carved oxide piece all finished:

 I think it turned out nice!Under clear. If you check that last post you can see this pot bisked.

 And last but not least, Nina’s fascinating inlaid slip. the twist is, she inlays it into black slip which was applied early on and burnished. That’s why there are two shades- some is scraped where she was cleaning up the inlay. She used a syringe to inlay the white slip. Good idea, eh? and neat pattern!

So thank you everyone for wonderful contributions and participation. It was really a great class that I looked forward to every week. What a pity it was only 4 weeks!