Building organic negative spaces using water-soluble clay as a resist

The real article this time. Sorry for the logorrhea, I tried to cover as many aspects as I could, to make a primer for further work.

Single bake complex pod with paint dot tests. Picture by M. Medenica

This work comes from the tests I did for the 3D challenge of the EuroSynergy polymer clay conference, I am sharing it here for a larger use. The technique is quite free for use, if you felt it was useful to you I would love to see what you got out of it.

I hope this can offer new leads. It is not a tutorial per se, but I tried to describe enough of the technique for others to reproduce, do their own tests and hopefully build on it. All the presented pieces are proof of concept and could be considerably ameliorated, but as those who saw them at Eurosynergy 2 can tell, they withstand manipulation and transport well.

A word of caution: while my tests did not show any problem with baking the water soluble clay (abbreviated in WSC from here onward) at the temperatures used to bake polymer clay, I do advise caution when using this technique, to avoid any fire hazard. I did not try the Kato clay, but Fimo, Pardo and Premo all worked fine for me at the normal baking temperatures and slightly above. Use at your own peril. 

The technique builds directly on the work started in 2012 on playdoh canes (negative spaces in canes, stained glass effects...), but trying to push it further. As usual, I got lost in the technical experimenting and went into multiple different directions.

I set myself two rules:

- Using the playdoh as a resist for an organic work with negative spaces

- Only a single bake for all the layers at once

The single bake was initially to keep with the 90 min restriction of the challenge, but it proved very interesting to work around (or with).

First some pointers and caveats :

Brand of water soluble clay

I use playdoh modelling clay because it is easy to find (I stole it in my own child's room, bad mother that I am), not too expensive, very soft and fine, and it dries but does not bake in the oven. It is quite probable that other water soluble and children modelling clays (including home made) would do just as well, and might offer interesting alternatives for price, softness, etc.

Softness of the water soluble clay

Playdoh is softer than most polymer clays (I have yet to try with Sculpey ultralight, but all the others are harder). 

Reduction when caning will always flatten more the playdoh part than the rest of the cane, and some will come out at the ends. So it works better in combination with softer clays for caning, to limit the difference between the components. When creating a cane for reduction, a very soft polymer clay like Cernit or Pardo works best. I have obtained reductions where the openings are reduced to pinholes with both of these (like the plankton beads). If the cane does not need to be reduced, harder clays can be used. Precision work is difficult, and the cane gets easily deformed when cutting the slices.

The softness is an advantage when using it as a resist, as it will not distort textured surfaces (except if pressed strongly on them, but why would you want to do that ?).

For projects where the WSC is only used as a support, harder clays might be a better choice, but it is also great to help very soft clays remain standing in the oven.

Shaping

The WSC can be shaped by hand, but also using the pasta machine, the clay gun or other tools. The tools should be cleaned rapidly to avoid small pieces to dry and contaminate further polymer projects. Wet paper towels or baby wipes are great for this.

Drying

Playdoh is water soluble, and dries when exposed to air and in the oven. It shrinks when drying, and larger surfaces crack.

Canes containing WSC are best used when fresh, because it becomes difficult to cut them reliably when some parts are dry. Plasticisers can also leach in the dry playdoh after a while. It is possible to keep canes from drying for a while by packing them carefully in plastic, but changes in texture occur after a while.

It should be possible to use dried shapes from playdoh, after carefully checking for cracks. It is also possible to fill the cracks with fresh playdoh, but the process might have to be repeated before obtaining a relatively smooth surface.

Combining playdoh with other support material is quite possible too. It is very good as a coating to protect the polymer surface against rougher fill materials like crumpled paper or aluminium.

Baking

The water soluble clay buffers the internal parts from the baking temperatures, but it also takes longer to heat correctly. I recommend longer baking times to ensure baking to the core (2-3 times the standard recommended time). Small amounts of WSC dry completely during the baking. Larger amounts used as a core are generally dry on the surface, but remain malleable inside.

I use slightly higher temperatures than recommended by the manufacturers, as has been established by many polymer artists. I will give the baking time and rough size for each piece presented as an indication.

Removal of the water soluble clay

All it takes is immersing the baked piece in water and waiting. It might however take considerable time when dealing with larger amounts of WSC, so minimisation of the amount of WSC used and manual removal of as much as possible are good options to accelerate the process.

Dissolving starts at the surface, and as the layers are removed the deeper parts of the WSC absorb more water and start to disintegrate. If you provide more surface for the water (by scratching the WSC for instance), or access to the heart of the playdoh, you will be able to remove it faster. You can do this by poking holes in it, integrating a rough piece of thread that you pull out before immersing (leaving a conduit for the water where it used to be). You can also, depending on how your structure is constructed, just pull out chunks of softened playdoh using a tool. 

A directed water spray (under the tap for instance) also speeds up things considerably, but it can still take days of intermittent cleaning and immersion for complex pieces with little access.

I noticed no difference between hot and cold water as for the efficiency, but I did not make systematic tests.

The recovered chunks of WSC can be dried slightly and reused in another project after mixing. However a lot of the playdoh will be washed out and lost.

Surface

The WSC will leaves a matte finish, and on Premo needs to be slightly polished on surfaces.

I have not tried with Kato though.

Color transfer

I have been repeatedly asked whether the color of the WSC is important. The large playdoh color packs generally contain bright colors, but there are also some light neutrals (very light yellow, cream) and white available.

I had fuschia playdoh give translucent pardo (here and here) a pink tinge, and also to white Fimo classic (here). I had no problems with Cernit and Premo, however the projects included no white or untinted translucent. I now try to use playdoh colors closer to the clay color, but I used purple for the pods with no ill effect.

Resists where you don't need them

As long as the WSC is there, it binds the pieces of polymer clay together. Once it is removed, they can separate if they are not solidly linked to each other. This is why the playdoh wood cane needs a backing, and any project containing large amounts of playdoh might be less sound structurally, unless great care is taken in the polymer clay-polymer clay connections. As the water soluble clay is very soft, some can be dragged by the blade when cutting playdoh canes, and prevent the slice from adhering on the backing as there is a fine layer of WSC between the two. This can be avoided by being careful, checking the cleanness of the slices, and using liquid clay.

Now on to some applications and examples.

Clay layers metamorphism

A stack cane alternating polymer and WSC can be used to create surfaces covered with lamellar structures separated by spaces. These can be deformed at will, as the water soluble clay layers prevents the lamellar polymer clay structures from touching each other, acting like a resist. 

The stack with pression tests. The WSC gets spread and pushed out, and the deformation does not get to the core. Materials layering and resistance 101.

The WSC is softer than the polymer, so it will deform more, and deformation patterns will not reach the center of a thicker stack. Reduction of the stack is possible, but will be limited, as the WSC is easily pushed out. Assembling it with fine sheets of soft polymer is the best option.

After assembly. Not much to see.

This piece was created by placing thick slices (around 5mm) of a simple stack cane on a shaped polymer base. For better contrast the polymer layers have one black and one gold side. On one side the layered cane was wrapped in simple organic patterns before cutting, the other side was covered by straight slices.

One of the simple organic canes: one layer green WSC (created here unwisely aligning extruded threads; the pasta machine is much more efficient) on one layer of clay (here with one gold side and one black side), coiled on itself.

This was one of the first tests, and I did not pay enough attention to WSC remaining below the slices, so some parts were insufficiently in contact with the clay base and broke when manipulated. However most of them are quite strong despite this.

Premo, 2h bake. Organic side. Some parts of the pattern decided to get away. Picture by M. Medenica

Definitely needs more cleaning of the playdoh. Picture by M. Medenica

A second piece with finer layers of polymer, and tests with covering a surface with distinct clay cylinders wrapped with playdoh to maintain the space between them. I had problems with the adhesion of some parts too, while others are quite well attached. Of course, the smaller the attaching surface, the worse the potential problem. One solution is to remove the WSC scaffolding, and add a thin layer of liquid clay at the base between the structures. This considerably strengthens the whole.

Lots of broken parts, but it is possible to assemble bull's eye cane with polymer inside and WSC outside to obtain regular spacing. The lined part was assembled from six slices from the same distorded stack cane. 2 hour bake, Premo. 

Premo on a premo base and a light core, 2 hour bake. The straight lines were pushed and moved slightly to make an undulating surface.

Twisted ropes and braids

Polymer clay strands have long been twisted, braided, and otherwise associated to create more complex structures. It is possible to replace one or several of the strands by a rolled or extruded playdoh strand. The presence of a strand when braiding/twisting prevents flattening and helps considerably with regularity. When it is removed, it reveals the remaining regularly spaced and undulating polymer clay strands.

As the WSC is very soft, it is sometimes difficult to work with long, fine strands. However additional pieces can easily be added to make a longer piece as needed. As the WSC is removed afterwards, the only thing to pay attention to is the regularity at the junction. The softness of the WSC has another advantage: textured strands will be protected even as they are twisted.
These are all one hour bakes, with different clay brands.

Braid tests immersed after baking. The large one is hemp, WSC, and Cernit. It withstood pretty rough treatment at EuroSynergy.

Three strand braid using tinted Pardo translucent. One larger clay strand, two finer clay strands manipulated as one, and one WSC strand. I made the error of using a soda can as a support, and the WSC could not shrink as it wanted and broke the clay. 

Three strand braid (one WSC, one black clay with knitting hairy thread, and one green clay). Cernit.

 It is also possible to dispose around a clay core and twist:

Extruded square WSC core, flattened textured Pardo on both sides. Assembled straight, and then twisted and closed. The WSC protected the inside texture and gold powder.

The extruded earrings before baking. Wrapping with extruded strands is not the best or easiest way.

Six extruded strands wrapped with extruded WSC. Again, it would have been easier to use a WSC sheet made with the pasta machine. The strands ends were left free at both ends, and the six wrapped strands were pinched together. The whole was twisted, bent, and the two ends were pinched together around a metal pin. The WSC supports the strands during baking well appart from each other.

Premo. 30 min bake. Top from the front, bottom from the side.

Structures within structures, in a single bake

I had made some tests with the external part of these pods. These are simple bull's eye canes arranged in two lines, the cane is then shaped like an ellipse and cut. The slices are arranged around an elliptical WSC core, assembled at the ends and twisted or shaped for a more dynamical shape.

Pod tests.

I then tried shapes within a protective but see-through external shell. The idea came from the floral diagrams used in botanical studies, so I started by a flower.
These are very hard to photograph, and I want to thank Martina Medenica who took the time to help me by making the pictures, and especially that of the red flower (and just in time, as I managed to break one of the petals the next day).

Premo, four hour single bake. Picture by M. Medenica.

The inside of the flower. Premo seems more modified in surface by the WSC. Picture by M. Medenica.

Just start in the middle, and build from there. Decide the shape and color of the center, prepare it, and wrap it with playdoh leaving the end(s) free for contact with the other polymer components.

I got wiser and used sheets of WSC this time. Cernit

 Add the next layers of components, insuring contact with the inside polymer by pinching the ends carefully.

Wiggly stamen thingies

Wrap again in WSC to separate the layers. Repeat these steps as many times as needed. 

Add an external layer you can see the inside through. This layer can be twisted and shaped, the WSC buffers the inside.

Before the sepals

Bake once, but long enough for the internal parts to be baked properly. I used 2h for the Cernit pods.<2cm 4="" 5="" and="" around="" cm="" flower="" for="" p="" premo="" that="" the="" wide.="" wide="">

The WSC contracted and cracked after baking. So did the sepals in places, because there was not enough clay-clay contact

Pods after baking

And after baking and removing the playdoh. The pod is attached on the hemp and polymer braid.

Reusing the scraps

The water soluble clay adheres to the polymer clay, so it is difficult to remove once in contact. Completely mixed together, they are structurally weak. But the scraps containing bits of water soluble clay can still be used, at several levels of transformation. It might be worth to remove a bit of the playdoh (or add pure polymer clay pieces) to make a more cohesive material if the ratio is too high.
These are all small, normal bake time projects.

- Cut into small pieces to create wood canes.

- Pressed and twisted to create interesting textures. 

Recycled rests from the plankton beads. Pardo.

These are deformed cane ends from the outside « leaves » of the pods.

Simple shaped cane ends. Cernit.

- Mixed partially. This corresponds to the color swirls stage when mixing polymer clay.

The proportion of the two components makes the difference between creating interesting surface effects with still a strong core, and having the piece come appart because the polymer clay parts are not in contact with each other anymore. The lime green pieces has approximatively 1/8^h of playdoh to polymer clay, and they are quite strong but very textured. The forest green piece has half half, and pieces detach from them when scratching. Adjusting the proportions approximatively removing one component or adding of the other is especially interesting in this case. The swirls can then take crayon, paint etc differentially, like any texture surface.

Water soluble clay as resist and support for large and fine structures

For my tile for the Fimo 50 years auction, I had a series of ancient Paris maps transferred on relatively fine sheets of Fimo clay, and wanted to have them ripping and opening in the middle. They needed some support, but the transfer and unbaked sheets surface were quite fragile. I simply buildt a support/separation between each layer of map, starting from the bottom and working upwards layer by layer, using a large piece of water soluble clay of the right shape as a separation. This was a two bake project, as there is a transfer on the back too.

Covering the 1000-something map with the support for the next layer. 3h bake project. 

I protected the raw transfers with acrylic medium before adding the water soluble clay to avoid smudging. This worked, although the brand I used reabsorbed water after baking and went white during the immersion. It dried clear again afterwards, and no damage was done to the transfer from the layering.

In this case, it was possible to remove and recover large amounts of playdoh as it was in only a few blocks and easily accessible.