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Casting into a Low Relief

Materials and Supplies

Working pulp = 
94% water, 6% pulp 

Dried = 
94% pulp, 6% water 

Sketches

Do Sketches first- but sculpture will adjust as you do it 

Potential Project: 
greeting cards and holiday decorations 
embellish with  found objects (spare buttons, postage stamps, beads). 

Molds 

• Press Terra Cotta Mold (or candy/candle molds)
• ? Objects to be cast 

(shells, butter molds, etc.) 

Any kind of mold is appropriate. Plaster molds can be coated with a non-latex, non-acrylic varnish. Some people have better luck removing cast paper from varnished plaster molds. The coat of varnish also can prolong the life of a plaster mold. Wet pulp sticks to acrylic and latex. 

If your piece is a medium to large bas relief, you will need sides on the mold about 1" high in order to hold enough pulp and water for your casting. Be sure that your mold is not absorbent to water. If it is made of plaster, seal it with shellac or varnish. Twinrocker sells an excellent urethane mold making material. It is a two part material which, when mixed together, will harden into a permanent mold for casting. 

Make Original Form

• Make object.  No undercuts 
• If object is porous, it needs to be waterproofed and treated with release agent.

Overview

• It is important that your first attempt not be too complex
• Pour pulp over shape, dry, gently remove form, yields negative impression in paper

Make the Mold 

Assemble the mold 
Waterproof frame 
If possible, measure the amount of water needed. 

Fiber 

• Pulp of any color or texture.
• Blend and sufficiently agitate
• Warm water aids dispersion.

Process 

• Clean work area.
• Work table should be free of dirt so no impurities get into the paper.
• Prepare positive mold
• Arrange composition
• Clean object (s).
• Thoroughly clean form so no impurities get into the paper.
• Cleaning solution = 1 teaspoon bleach, 3 drops dishwashing liquid, hot water
• Preparation objects:
• Spray object(s) with vegetable spray
• Dry

Rearrange objects:

Preparation of Clay objects: 

• Dry clay. 
• Coat with vegetable spray 

Preparation of Natural objects: 

• Spray inside of object with vegetable spray
• Drill holes in bottom of form to help water drain (if you do not need to use the object anymore in its original state)

Tape holes from outside to prevent strands from coming through.

For Variety 

• Each layer can be a different color

Objects can be completely covered or penetrate top layer.

Making a Plaster Mold 

• modeling clay objects 
• plaster-molding plaster #1 
• Georgia Pacific K59 
• plaster mix bucket 
• mold release 
•  vaseline 
•  soft soap 
•  buff paste wax 
• wood for frame 
• (can pre-make forms) 
• brackets & brass screws 
• silicone sealer 
• small brush (1/2") 
• base of formica 
• 1x4" wood for molds 
• clay seal edge of wood frame to formica

Mix Plaster:  

• Measured approximate of water from mold 
• Sprinkle plaster into water in mixing bowls 
• Plaster will begin to float on surface of water 
• Mix with hand - get rid of lumps - avoid air bubbles 
• Tap bowl on table to release some air bubbles. 
• Pour plaster into lowest area of mold and allow the plaster to rise over the object. 
• Tap mold lightly to raise any bubbles away from surface. 
• The plaster will warm and cool as part of the setting up process. 

Clean-up Plaster:  

• clean utensils - do not let plaster go down the drain

Mold 

• shellac or varnish

If your piece is a medium to large bas relief, you will need sides on the mold about 1" high in order to hold enough pulp and water for your casting. Be sure that your mold is not absorbent to water. If it is made of plaster, seal it with shellac or varnish. 

Twinrocker sells an excellent urethane mold making material. It is a two part material which, when mixed together, will harden into a permanent mold for casting.

Prepare Mold for Casting 

• parting agent
• Silicone Spray Lubricant

It is important that the mould does not encourage the fiber to adhere to it. 
Mold Releases 
Releases can be problematic because the paper is porous. Vegetable oil grows mildew after a while and ruins the surface of the paper to boot (as do wax or Vaseline thinned with mineral spirits). Talc sticks to the paper and mottles the paint. 

Be sure to coat any mold with a parting agent, either the wax spray Twinrocker sells or a silicone spray for door locks. Let it dry after spraying. 

Pour Pulp and Water into Mold

Be sure there's plenty of water in the mixture you pour. 

Fibers for Cast Sculpture 

• Twinrocker #27 (medium beat)
• sized
• methyl cellulose

For dimensional paper, cotton linter pulp is recommended because its short furry fibers provide maximum bonding surface for maximum strength in the finished product. Those same short fibers pick up detail more easily than longer fibers would; and they don't normally shrink or warp. 

However, the sheer amount of pulp used in molding reliefs or building sculptures somewhat mitigates the importance of those issues. Beautiful but longer fibered pulps like abaca or cotton rag can produce exciting results. Exceptions are when fine linear detail is an essential design element or the project has zero tolerance for shrinkage or warping. Linen pulp is an interesting choice for hand-manipulated sculpture - it stretches while it's being worked and then shrinks when it dries. It can give a fascinating wrinkled surface. Pulps from Oriental fibers are not worthwhile here. 

Papier mache, that is re-pulped paper, is a possible material; but an inferior material because the second pulping constitutes overbeating. Further, you don't know what's in it. Some of the chemicals that went into forming it the first time come out when it's soaked; but some of them seem to stay in until the sculpture starts drying, at which time they rise to the surface and turn edges brown (foxing). 

The rules of coventional hand papermaking apply in the process of preparing pulp and keeping it uncontaminated. 

Mechanics 

• Sponges
• Buckets

a kitchen strainer

POUR THE PULP & WATER MIXTURE INTO THE MOLD: Be sure there's plenty of water in the mixture you pour. 

      To get even coverage on/in a mold with paper pulp, it's easiest to slop the saturated pulp in and then sponge it down, so the pulp doesn't stick to the sponge, with as much manual pressure as possible to remove still more water. (The best drained pulp is still very wet!) Sponging through plastic window screen or paper mould screen keeps the pulp from sticking to the sponge. Deep relief areas require extra finger pressing, and perhaps laminating, to make sure the pulp gets into every nook and cranny. When it's as dry as sponging can get it, the pulp scrumbles into little tiny rolls. 
 

Thickness of the non-relief areas should be the at least as thick as a sheet of the same pulp would be (for a vacuum table) and twice to three times that for air-drying under pressure. It doesn't matter whether the relief portions are filled flush for a flat back or left hollow. In most cases the pulp decides that, anyway. 

Pour Pulp 

• Slowly pour pulp into dish or mold taking care not to move objects.
• Pour apx 1/3 of desired total, this first level anchors the objects.
• Use wooden spoon to spread pulp into areas where pulp is not evenly spread.
• After first layer is spread, pour more pulp and use spatula and spoon to spread and even out the layer.

Sizing 

Internal Sizing 

Other Additives 

White china clay added to the vat in small doses gives the paper a nicely paintable, almost porcelain finish. Whiteners, dyes, pigments can be used in casting- or sculpting pulp. Too much of any additive interferes with bonding, but again because of the sheer amount of pulp used, the consequences of too much can be minimal. 

Consistency 

Twinrocker #27 Medium Beat 
casting-pulp. 
useable the minute the clumps disperse. Casting-pulp should be about the consistency of heavy mashed potatoes, so it requires preliminary water removal to get it from absolutley floating to merely saturated (roughly half water/half fiber). 
I let it sit undisturbed for a few hours, pour off the water that rises to the top, and strain the rest. 

Pat (Press) the Pulp into the mold

This is probably the most important step in the process. By patting the pulp directly with your hand, you jiggle the pulp fibers down into the detail at the bottom of the mold. This is also why it is so important to have enough water in the pulp mixture. When you are learning, pat the pulp three times as much as you think you should.

Remove the water from the pulp 

Begin by laying a "real' cellulose sponge on top of the pulp and water mixture, when it has absorbed as much water as it can, squeeze it out and continue working the sponge slowly around the sculpture, absorbing water and squeezing out the sponge. Slowly begin to PRESS as you absorb the water. Continue to do this until you are PRESSING AS HARD AS YOU CAN WITH THE SPONGE ON THE PAPER PULP AND TAKING AS MUCH WATER OUT AS YOU CAN. 

A vacuum table accomplishes the same result with less trouble and decreases the air drying time significantly. It's also the best device for capturing fine detail perfectly. It produces paper that's as hard and dense as bricks. I've heard that's the way pith helmets are made. 

Full 3-D sculpture is probably best accomplished with materials other than paper. For those who want to do it anyway, the best way is to form thick sheets and let them dry under medium weight until they feel like raw pie crust dough (after it's been rolled out). Then tear them into strips and apply them to the armature. Dipping the strips into methyl cellulose (or other glue) before they're wrapped gives them great workablility and helps the overall piece retain its modeling. 

The same goes for bas relief paper sculpture - think collage and keep layering. Hand pressing and squeezing with a sponge to remove every bit of water possible is part of the action. It gets messy when glue is involved, but it's necessary. 

Dry the Casting

Dry in the air. Bear in mind that warping is caused by one area (or areas) drying before the rest of the piece. If you place it in the. sun or use fans be sure to cover the surface of the casting with something absorbent like a terrycloth towel or blotters. A warm, dry chamber with little air movement is ideal, like a closet with a dehumidifier in it. With a medium to large mold, you may need to weight the edges of the casting to keep them from warping up. DON'T TRY TO TAKE THE SCULPTURE OUT OF THE MOLD UNTIL IT IS COMPLETELY DRY!!  

Drying and Pressing 
Drying is a major concern in cast paper and paper sculpture. The idea is to arrive at strong paper by drying it as quickly and evenly as possible in a way that prevents further retting (rotting, breaking down) and keeps shrinkage/warping and exposure to environmental pollution all to a minimum. 
 

Bas relief paper sculpture has to be dried in open air if it has elements a press would flatten. In that case, it should be sponged firmly every day until it's bone-dry. The glue does not eliminate all need for pressure. 

Fully 3-D pieces have to be sponged and air-dried. Again, there are far more suitable materials than paper for sculpture in the round. 
If the pulp feels the slightest bit cool or cold anywhere, or there's the tiniest damp spot on the exposed surface, it's still wet somewhere
problems getting the entire casting out of the mold in one piece arise because the paper is still damp somewhere in the middle and comes apart at that point. . 

• Note: Excess water left in the pulp will produce a Paper Casting with a wrinkled finish.

• Dry the pulp completely in the mold. You can do this by leaving it on the counter overnight, in the sun for 4 hours, or in a 200°-225° oven for about a half an hour. You can also dry the molds in the microwave by placing it in the center of a microwave oven and set on full power for 1 1/2 minutes. Open the microwave door for about 1 minute to allow steam to escape. Microwave in 20 second intervals until the mold is completely dry.
When the paper is completely dry, carefully lift the edges with a thin, sharp knife and peel the paper out of the mold.

Dry paper form 

• Remember that paper is combustible 
• To speed drying
• Put in gas oven with only pilot light on
• Place near a heat vent
• xes.

 
 Remove objects from paper 

• After paper is completely dry
• Insert knife or shim and gently pry or loosen strands holding it in the paper.

Invert and remove 3D objet.

Finishing 

After the paper is dry, and removed from the mold. It should cure in a dry, warmish, well-ventilated place for a week or two before it receives any surface re-wetting with paint or protective coating. Working on it too soon risks rehydrating to pulp. 

Safety 

Rubber gloves, safety lenses, and a dust mask are standard equipment for work with fibers and pulp. Pulp should be confined to wet area until curing is complete.