Sgraffito Technique

The next decorating technique that I’ll be demonstrating is sgraffito (which roughly means ‘scratch’ in Italian). It’s fairly straightforward and easy to do once you get a feel for when the best time to scratch through the underglaze is. Often times people make their own slips or underglazes (which are both quite similar in makeup) from their own formulas. Here is an underglaze formula from Vince Pitelka, and a decorating slip formula from Big Ceramic Store, if you’re interested in mixing your own batches.

I’ve used Amaco’s LUG (Liquid Underglaze) and Velvets series, both of which can be used on greenware or bisque. Spectrum’s 500 series can also be used on both. Duncan Concepts are for bisque only and so won’t work for this type of sgraffito. Make sure that the brand you pick can be used on greenware. Any color of underglaze may be used but in terms of contrast, naturally, dark underglaze will look better on light colored clay and light underglaze will look better on dark clay.

Here are pics of the three pendants I applied this technique to in the video:

 The top photo is after a Cone 04 bisque firing, and the bottom are the finished pendants after a Cone 05 glaze firing.

My Sgraffito Video, showing how these pendants were made and brought to completion (you'll be better off clicking the 'YouTube' icon on the video to watch it at their site, I can't seem to get the video to appear larger here):

 Supply List:
--Cheese- to Leather-hard clay; rolled out, cut, cleaned and prepped with hole/wire as desired.
--Small brushes with long bristles. I bought a set of mop brushes that had a couple with 1/4” to 1/2” wide brush heads.
--Duster brush to sweep away debris. I use an old blush/powder brush with sable bristles.
--Sgraffito tools: In the video I use the Kemper DBS and DBSS ball-tipped tools, the WLS wire stylus and the WS wire stylus. Many different tools can be used instead, including dental tools, a pencil, quill, skewer, pin tool, about anything with a fine tip will work.
-Underglaze, prepared, any color, shaken and stirred well
-Magnification headset, optional, helps when scratching fine details if your eyesight is weak
-Latex gloves as a precaution


Step 1: Dampen a brush with water and then load up with underglaze. You’ll get a feel for how much liquid to pick up on your brush after you’ve done a few pieces. The brush I use takes in too much for the small area of a pendant, so I wipe one side of the brush against the side of the container to get rid of half of it before brushing.
I try and brush in only one direction, but this usually leaves one edge with too much underglaze piling up, so I’ll brush it at an angle in the opposite direction to help even it out. You’re going for a smooth, even coat, without stirring up a lot of clay. The underglaze can get muddy-looking if the brush moves too much clay around, so try and minimize the number of strokes while keeping the coat even.

One coat is usually sufficient to cover the clay well. If you see the clay through the underglaze, it will probably need another coat.

For an interesting effect, a coat of one color may be brushed on, left to dry, and then a second coat of another color applied over the first. When you scratch through using varying pressure on the tool, some of the first layer’s color will remain if the lines are not too deep to reach the clay. This method works better when the piece has dried to bone dry. Either apply the underglaze when the piece is bone dry or let an underglazed piece go to bone dry.

The underglaze that I use (Velvets and LUG) may be applied at any greenware stage, from wet to bone dry, as well as to bisque. When brushed on wet stage clay, the underglaze stays like finger paints for awhile and dries very slowly. When brushed on cheese to leather hard stage and left to dry, the underglaze and clay are soft and it is easy to achieve fine lines and carving effects. When applied to bone dry stage clay, the underglaze and clay are both like compressed powder; designs may still be scratched through, but when lines intersect the space between the lines tends to flake off. I usually save my less detailed designs for bone dry sgraffito. You’ll find your own preference for which stage works best for your type of designs.

Step 2: Wait for the underglaze to dry. The color will lighten slightly and will no longer feel cool to the touch when it’s dry. Sometimes it helps to turn off the bright overhead light if you’re using one in order to see if there are damp parts still left on a piece (the shadows are clearer in dimmer light).

Step 3: You can start scratching through the underglaze with a fine-tipped tool freehand as I did in the video, or for more complex designs you can use a stencil or cutout to lightly trace the main outline of the design with a pin tool or other suitable instrument, and then add the finer details after removing the stencil. For larger areas of underglaze removal, I use the Kemper WS wire stylus, and for wider lines I use the WLS stylus.

Step 4: After the design is complete, the piece is left to dry for 3-4 days, depending on the humidity level. I usually keep the boards full of finished pieces covered lightly with a sheet of bubble wrap. It slows down the drying to keep warpage to a minimum.

Step 6: The pendants and tile are then bisque fired to Cone 04 using the Fast Bisque cone-fire setting on the computer controller of my electric test kiln.

Step 7: I brushed three coats of Amaco LG-10 clear to the black and white pendant and the tile, and two coats of Duncan Envision Peacock on the pendant with green lines, and Duncan Envision Grape on the purple pendant.

Step 8: The pendants and tile were then fired to Cone 05 using the Slow Glaze cone-fire program.

That’s about all there is to it, a pretty easy technique, eh? Next time I’ll be demo’ing Staining, as seen in the bottom right group of pendants here and the upper half of the tile:

Until then, may your hands be ever so muddy...have fun!

Making Bisque Stamps for Impressing Into Clay

Stamped impressions are an easy way to add a raised image to the clay surface, and give the ability to produce multiple pieces with the same design fairly quickly. Stamps, rollers, texture mats, and found objects are all tools used to impress a design onto clay. Here are a couple of photos of the pendants I stamped in the last video:

The first pic is the raw clay after stamping and cleanup, the 2nd & 3rd is after bisque firing to Cone 04, and the last is after brushing on 3 coats of colored transparent glaze (Duncan Envision Clear Black and Grape) and firing again, this time to Cone 06, along with the bisque stamps that made the impressions at the raw clay stage.

I used bisque stamps for these pendants, but there are many options when it comes to impressing texture/designs into clay.

Where do you find the tools for clay impression? You could (A)make your own, (B)use found objects such as plants and shells, or (C)buy commercially made stamps/tools.

(A) Make Your Own
Make your own stamps, rollers and texture mats out of clay and then bisque fire (tutorial below with links to other tutorials); or carve into plaster, wood, linoleum, polymer or air-dry clay. The principal is the same with all of these materials: incise/carve a design into a flat face on the material (or with soft material like clay you can use found objects instead of incising--see ‘found objects’ below), fire it to bisque or cure it as necessary (polymer/air dry clay); it is then pressed into moist clay, leaving a positive/raised impression of the design on the clay. The design you incise/carve/impress on the stamp face should be no more than 1/16” inch deep, or else it will later make it hard to impress the deepest recesses of the stamp design without deforming the clay it’s being pressed into.

I make bisque stamp discs which are initially cut from a 1/4” thick slab of leather-hard low-fire white clay. Alternatively, you could slice pieces off of a coil or use a small ball of clay with a flattened face to hold the design.


Tutorial/Video: Making and Using Clay Bisque Stamps:

Step 1: Use a cutter to remove a circle from a rolled out slab of leather-hard clay. I use the same cutter that I use to cut out pendants (the bisque stamp will be slightly smaller than a raw clay cutout because of shrinkage in the bisque), or a cutter that is slightly smaller than my pendant cutter. Because I use a round cutter, a circle will be part of the impression left on wet clay. If I want a triangular impression with no circle as a background, I would cut the entire stamp into a triangle so that it would be the only shape comprising the background.
Step 2: Using wire, loop and/or ball-tipped tools, outline and then incise your design onto the top face of the clay cutout to no deeper than 1/16”. Use a soft brush (I use a makeup/powder brush) to swipe away the loose clay bits but while incising, try not to worry too much about the burrs and leftover clay along the lines. As the clay dries, these will be easier to brush away and the lines can be gone over again and smoothed over with you finger, a wood tool, or a barely damp sponge or soft, short-bristled brush (I use an eyeshadow brush for this).

If you’re not sure what to carve and/or don’t want to draw freehand, try Googling ‘black and white outline’, ‘silouhette’ or something similar to see some stock drawings. Download one that you like, or draw your own and then size it in Adobe Illustrator or other drawing application, print it up and transfer the image to the wet to leather-hard slab by slightly wetting the slab with a sponge and then lightly burnishing the printout onto the slab. This will leave an inked image on the slab (which burns off in the firing); you’ll then be able to easily see where your cutout and incision/carving lines are. These are the completed stamps in the video, and the impressions that they leave. Normally I would cut out the clay pendant shapes first, and then stamp them.

Other Blogs Demonstrating How To Make Stamps, Rollers, and Texture Mats for Clay:

Nancy Gallagher Pottery: Making Bisque Stamps and Texture Mats
Ceramic Arts Daily: Making Polymer Clay Texture Stamps 
 Tara Robertson/My Pottery Blog: Bisque Stamps
Ceramic Arts Daily: Making a Bisque Texture Mat with Fresh Flowers

B) Found Objects: Instead of using found objects to make bisque stamps as above, impress them directly onto the clay surface with each piece. That is, you’re using the object to make the impression each time you make a tile/pendant/whatever instead of using a stamp made out of an impression of the object. The design won’t be raised like a stamped design is, of course. You can use things like netting, lace, buttons, wallpaper, shells, wood, plants...anything with a nice texture or relief will work. Thrift shops and flea markets offer good opportunities to pick up some old buttons, etc.

C) Commercial Sources, here's a few to get you started:

 Lisa Pavelka: Silicone Stamps and Texture Mats
 ClayStamps on Etsy: Bisque rollers and stamps
 MKM Wood Stamps at Big Ceramics Store
Xiem Clay Rollers at Bailey Pottery
Plaster Texture Molds at Dogwood Ceramics
Art Clay World USA: Rubber Stamps and Texture Mats.
Stampin.com: Rubber Stamps
Inkadinkado: Rubber Stamps

Above, I've used a commercially made wood stamps, leaves, shells, and stamps made of carved plaster and air-dry clay to leave impressions in the slab.

How to Use Impressing Tools:
Stamps: Apply equal pressure to the stamp as it is pressed into the clay. If the stamp is composed of non-porous material such as rubber, silicone, linoleum or polymer/air-dry clay, it is best to dust the stamp with a small amount of a release agent such as cornstarch before impressing.

Rollers: Roll over the slab before cutting out pendants/tile, or if cut out clay is still wet enough may be able to roll after cutting out.

Texture Mats: You’ll want to transfer the slab to the texture mat and then roll over the top of the slab with a rolling pin, with the texture mat underneath

Found Objects: Use a pastry/flower roller to press plants into the clay, other objects will take experimenting with, usually just press it in and see what you get!


Here's a pic of the finished pieces I'll be demonstrating the surface treatments for in upcoming videos:

The tile has sgraffito and staining, the stamped/impressed pendants for this post are in the upper right, the stained pendants are in the lower right and the sgraffito pendants are in the lower left. I'll be going over how each of these decorating techniques works as well as bisque firing, glazing, and glaze firing. Thanks for reading/viewing, and for now it's back to the slab! Have fun out there playing in the clay now...