description of laminate process

(Note: A fabulously detailed and lucid explanation of the general process and specific appliations is presented by Vince Pitelka in his text "Clay: A Studio Handbook" and is well worth reading. I'd read anything he wrote.)

I'd like to fill in details missing from the earlier post's commentary. The murrini/laminate process is based upon a few premises, so forgive me if I repeat something you already know.

1. Clay is usually soft enough that you can force it through tiny openings, or extrude it, as the jargon goes. The contraption used is usually some kind of barrel with a tight-fitting plunger that passes all the way through from one direction. These can be large wall-mounted units where the barrel is several inches in diameter, to small crafty versions about the diamter of a nickle. In between are home-brew versions made from sections of PVC pipe and an altered caulking gun ratchet thing.

In all extruders, clay is loaded into the barrel and squeezed out the opposite end by pushing the plunger. Obviously, if you want something other than the shape of the barrel, you have to create something for the clay to pass through. The end is capped by anything strong enough to withstand the pressure of the clay, and the forces can become quite tremendous, especially if the clay is harder than necessary. These caps are often called extruder dies. in commercially made sets, solid simple shapes are common, such as circles, ovals, squares, triangles, etc, but more elaborate profiles, including hollow shapes, are possible.

For my process, every different element of the design will have its own die made for it. Were I smart, I'd try to simplify the overall design to include not 7 different sizes of circle, but perhaps 3. At the moment of extrusion, I have a long strand of clay, which has the cross-section of the die opening, which is one of the separate components of my design. Many clay artists have used this process for their work, but I might be stretching the limits of what a person is likely to do.

2. Clay can be colored by mixing ceramic stains into it. The color range of these mixtures is usually broad enough to satisfy most artists' needs.

For my project, not only will the sections be the correct shape for their position in the overall pattern, but also the correct color, because I will have mixed the color of clay I need before extruding it.

Here's how I think the process will work.

a. Design the pattern using as few shapes as possible.
b. create dies for them all.
c. decide what colors are available (tested separately) and assign colors to each of the sections.
d. extrude as many of the different elements as needed to create the overall pattern.
e. fit the extrusions together like a 3D jigsaw puzzle and make sure they stick. A simple overall pattern log might consist of piles and piles of circular extrusions in a variety of colors. Note that stacks of fairly large circular extrusion will have blank interstitial spaces which need to be dealt with. It is possible that the laminate will hold together despite the holes between the perfect circles. It is possible to squash the whole log so that the spaces close up as the circles are forced into each other, becoming oval or some other distorted shape. Another way to deal with the holes left by perfect circles is to use some liquid clay slush, possibly also colored, possibly a contrasting color, to bathe all the separate extrusions and act like spackle.

(at this point, the log is finished)

f. remove thin slices from the short end (or whatever face lies at 90 degrees to the direction the extrusions were created in.
g. use a slice, which is nothing more than an elaborately created thin floppy bit of clay, and apply it to whatever ceramic object is waiting for it.
h. take a bow.

There are technical timing issues, which can wait to be discussed. The clay object was formed in whatever way was convenient, in the bird whistles' case, they were cast. I'm guessing a Day in the Studio would look something like the following.

a. design pattern log.
a. Cast a goodly number of birds and prepare them as much as needed so that decoration can take place.
b. Get a blank bird. Slice off a thin slab from the pattern log and wrap it around the blank bird. Smooth everything down.
c. Repeat until you run out of something.

If the entire bird is not covered in the slab (which would be difficult anyway, given that while the slab is fairly elastic, the pattern might distort unpleasantly), then there's going to be naked bird parts. There will probably be a basecoat of bird background color applied before the laminate. I'm going to have to live with is the visible boundary between the slab and original surface. It might not be a big deal.


This ought to clear things up. :)

Next up: How are the dies made? In normal practice, discs of metal are sawn to fit your extruder, and the pattern element design is transferred to the metal and pierced and filed. In normal practice, a pattern might have 6-12 different elements. Mine might have dozens; in fact, I want them to have many dozens of shapes. (Do we really need more checkerboard murrini??) But, sensibly, I don't want to do all that sawing. But I have an idea that might make things much faster.

Stay tuned!