Paper Maché & Beyond

Basics

Paper maché, as it is referred to here, is shredded paper pulp that is combined with some sort of cementitious material, most commonly plaster, and shipped either in block form or loose in bags. Most often it comes in 1 pound, 5 pound and 25-pound blocks or bags however, it can also be ordered in larger quantities.

A liquid is mixed into it to start an irreversible, catalytic reaction that eventually causes the mixture to harden.

The brands most easily found include Celluclay, Sculptamold, Claycrete, and Shredimix. All are similar however, I have found Celluclay to be the strongest and most versatile for most applications. Celluclay has recently added a new blend to their roster which sets in a much shorter time — about 2-4 hours depending on ambient humidity. As with all paper maché, the setting time can be hastened by heating in an oven at about 265° – 280° Fahrenheit

Both Claycrete and Sculptamold set in a relatively short time and do not have the ability to be stored and used later.

All these brands are available in the Sax Arts and Crafts catalogue as well as Dick Blick, Cascade, Flax and many others. Many art supply stores carry the materials and will even order it in larger quantities if you need it.

Instead of using water (the most common additive), I use a polymer based liquid called AddMix (also known as tile grout additive, underlayment sealer, concrete additive or sealer, or various other names). It resembles milk both in color and consistency and can be used not only in paper maché but also as the liquid to add to any material that calls for water to start the catalytic process. It is non-toxic, water-soluble and it makes any mixture markedly stronger (plaster increases in strength by about 3 times) and also makes many materials waterproof or water-resistant. It also tends to make the surface patina just a bit glossy.

General Instructions

Place a quantity of the dry pulp in a resealable refrigerator bag or something similar, as the pulp is rather dusty (though not toxic).
Pour in the water or additive (or some mixture thereof), seal the bag and knead the mixture to an even, moist consistency. If it’s too dry add more liquid, too wet add more pulp. There is no precise proportion and the mixture can be varied according to its intended use.
After mixing very thoroughly in the bag I’ve found that it is usually necessary to take it out and mix it with your hands. It’s really sticky but if you keep your hands moist with water it’s quite manageable.
If you’re going to add pigment – now’s the time to do it. Separate the maché into however many colors you want and wrap them up keeping out the amount you want to add color to. I usually use acrylic paint and start by squeezing out my colors I want to mix onto some paper. If I want a color other than a tube color I mix that before I blend it into the maché. I then dip my fingers into the paint and start to push it into the mix with my fingertips. I work it in by tearing the mix apart and recombining it adding more pigment as I go. When I think I have the color I want I wrap it up and let it sit.
Pigment or not the sitting part is important (it’s actually called slaking). You can let the mix sit at room temperature for several days or you can refrigerate it for several weeks. It even freezes! Once it slakes for at least a few hours I pull it apart to check for dry spots and add liquid as needed. More color may also be added at this time or mixes of different color may be combined for varied results.

Lots of other “stuff” can be mixed into the pulp. Dry pigments, fibers, other papers, concrete, plaster, plastic Etc. If you mix in stuff that can be filed and sanded they will appear on the surface suspended in the maché.

The maché will stick to most other materials and to itself. Even materials that are non-porous and resistant will work. PVC pipe, plastic 5 gal. buckets, wire, sheet metal, Plexiglas, all of these and many more can be used as armatures for or assembled with the paper maché. I found that a thin coat of polymer additive applied to the surface first allows the maché to stick better and not separate, even under stress.

The maché will air dry, however, depending on the thickness it may take some time. To hasten drying you can add the maché in thin layers, allowing each to dry before adding the next. The clay sticks to itself very well and can be made even stronger by coating the underlayers first. The pieces can also be baked in an oven or heated using a hair dryer, space heater with a fan or other such set-up. The temperature should not exceed 350° F and I have found that baking at a lower temp for a longer time yields a better product. I also found that when heating, a “ skin” forms around the piece and becomes almost waterproof. This seals the piece thus trapping moisture inside and basically steaming the piece on the inside. The piece therefore never dries and remains wet and soft on the inside while baking to a hard finish on the outside. To avoid this it is necessary to poke vent holes into the piece all over to allow the steam to escape. I use a needle tool or Xacto knife and stick it all over. These holes eventually seal up and must be reopened every half hour or so

After the Maché Hardens

Once hardened the maché can be treated much like a piece of wood. It can be sanded, sawn, filed, drilled, textured, polished, collaged upon, leafed, patinated, or any surface coating you choose.

Epoxy can be dribbled into cracks and crevices allowed to harden then be filed, sanded, and polished along with the whole piece so that it begins to resemble stone with veins running through it.

You can use polymer clay the same way, that is, forcing conditioned clay into cracks or areas that have been cut or drilled into the hardened maché and then baking it to harden the clay and proceed as above.

Any type of material that can be pushed into the maché will work. I’ve used auto body filler (acrylic paint will tint it), plaster (mixed with additive above), concrete, grout, stone chips (like for inlay in jewelry). Play with it.

I’ve been able to tap pieces of hardened maché (put in threads) by waxing a bolt and pressing the wet maché around it. I bake it with the bolt inside and when hard I back out the bolt leaving the threads behind.

The hardened work can be approached like a piece of wood. Sanding belts and wheels work very well and will yield an almost polished surface if a fine belt is used. Files, grinders, flex shafts with various burrs, and all manner of power tools and finishers are usable with the results varying accordingly.

When polishing, compounds stain the maché, which may be fine for you. However if you don’t want this and just want a polished surface you can sand down to a 600 grit paper then use a part sewn plain muslin wheel with light to medium pressure.

If you press or roll the maché out on a polished, waxed surface such as Plexiglas the hardened maché will have a shiny, polished surface when removed. This is just a start and I would appreciate any new information or discoveries you come across.

Play Well,
Robert