# Positives and the Multiple

Sculpture I · Modelling, Moulds and the Workshop · https://tryals.app/learn/sculpture-i/positives-and-the-multiple

## Casting Materials

The mould is a negative. The **positive** is what is cast in it.

| Material | Set | Character | Watch for |
|---|---|---|---|
| **Plaster** | Minutes | White, matt, fragile | Weak in tension; indoor only |
| **Resin (polyester)** | Minutes to hours | Hard, takes fillers | Styrene fumes; high heat |
| **Resin (epoxy)** | Hours | Stronger, clearer | Skin sensitiser; slower |
| **Concrete / GRC** | Hours to days | Heavy, weather-proof | Needs reinforcement |
| **Wax** | Minutes | Soft, remeltable | For bronze casting |
| **Ceramic slip** | Hours | Fired after casting | Shrinks; ceramic rules apply |

Two properties decide most material choices:
- **Exotherm**: resins release heat as they cure. Thick sections can overheat and crack the mould.
- **Shrinkage**: all casting materials contract. You must know the exact rate for precise work.

**Slip casting** is the ceramic process. Liquid clay fills a dry plaster mould. The plaster absorbs water, forming a solid clay wall before excess slip drains away. Wall thickness depends on **how long the slip sits in the mould**.

## The Multiple

A reusable mould allows multiple copies. Once created, it changes the status of the artwork.

- An **edition** is a fixed number of casts declared in advance. It may include extra **artist's proofs**.
- An edition limit is a social **convention**. Only the artist's declaration stops further production.
- **Posthumous casts** are produced after an artist's death. They remain physically identical but lack direct oversight.

This highlights an ontological distinction in art theory:
- A carved marble is **autographic**. Its unique physical history constitutes the artwork.
- A cast bronze is **allographic**. Multiple casts can be equally authentic.

> **Common pitfall:** assuming the first cast is the original. Every cast in an edition is equally authentic. An unauthorised cast differs only by the **absence of the artist's decision**.

## Practice questions

9 of this lesson's 14 practice questions, with answers. The full set is in the app.

### 1. In a properly declared edition of ten bronzes, what distinguishes the first cast from the seventh?

A. The first cast was authorised, whereas the seventh was not
B. The first is an autographic original; the rest are copies
C. The first is made from a fresh mould and retains detail
D. Only its position in the series; both are equally the work

**Answer:** D. Only its position in the series; both are equally the work

**Why:** Only its **position in the series**. All ten were authorised in advance, so all ten are equally the work (allographic multiples), and the fraction records where a cast sits in a declared sequence rather than how authentic it is.

Page: https://tryals.app/practice/sculpture-i/positives-and-the-multiple/in-a-properly-declared-edition-of-ten-bronzes-what-distinguishes-the

### 2. An edition is declared at ten casts. How many of them are equally the work?

**Answer:** 10

**Why:** **All ten.** The numbering records position, not authenticity, which is why "1/10" is not more the work than "9/10", and why the interesting question about any cast is whether it falls inside a declared, authorised edition at all.

Page: https://tryals.app/practice/sculpture-i/positives-and-the-multiple/an-edition-is-declared-at-ten-casts-how-many-of-them-are-equally-the

### 3. Slip casting controls wall thickness by how long the slip is left standing in the mould.

**Answer:** True

**Why:** **True**, and it makes slip casting unusual: **time directly sets the geometry**. The porous plaster draws water from the slip against its face, a wall of clay builds up, and pouring off the excess sooner or later gives a thinner or thicker wall from the identical mould.

Page: https://tryals.app/practice/sculpture-i/positives-and-the-multiple/slip-casting-controls-wall-thickness-by-how-long-the-slip-is-left

### 4. Which are true of exotherm in resin casting?

A. It is a reason resin casts are often made hollow
B. A thick section can reach a temperature that damages the mould
C. Curing resin releases heat
D. It shortens the time the resin takes to cure to a usable state

**Answer:** A. It is a reason resin casts are often made hollow; B. A thick section can reach a temperature that damages the mould; C. Curing resin releases heat

**Why:** The fourth mistakes a hazard for a benefit. A thick section can run away thermally, cracking the cast, damaging the mould and producing fumes, which is exactly why resin positives are usually built up as a hollow shell by rotating or brushing rather than poured solid.

Page: https://tryals.app/practice/sculpture-i/positives-and-the-multiple/which-are-true-of-exotherm-in-resin-casting

### 5. Sort each casting material by its principal characteristic.

**Answer:**

- Fragile and matt: Plaster, A chalky white surface
- Hard and pigmentable: Polyester resin, Takes fillers and pigments readily
- Heavy and weather-resistant: Concrete, Needs reinforcement at any scale

**Why:** The third column is the only one that survives outdoors, which is usually the decision that settles the material. Plaster is a studio and exhibition material; resin is durable but degrades in ultraviolet; concrete is what goes outside and brings a weight problem with it.

Page: https://tryals.app/practice/sculpture-i/positives-and-the-multiple/sort-each-casting-material-by-its-principal-characteristic

### 6. Complete the account of positives and editions.

**Answer:** Heat released by curing resin is its **exotherm**, which is why thick sections are avoided. Ceramic positives are made by **slip** casting, in which the porous plaster draws water from the liquid clay. A fixed number of casts declared in advance is an **edition**. Casts made from an artist's moulds after their death are **posthumous** casts.

**Why:** The last blank has no settled answer. Posthumous casts are physically identical to authorised ones and were made without the artist's decision, and practice and law differ by country, so it is a real disagreement rather than a question someone has failed to look up.

Page: https://tryals.app/practice/sculpture-i/positives-and-the-multiple/complete-the-account-of-positives-and-editions

### 7. A cast bronze is classed as allographic rather than autographic. What follows from this distinction when evaluating an unauthorised cast made from the original mould?

A. It lacks legitimacy purely because artist intent is missing
B. Its physical flaws prevent it from being a genuine multiple
C. It is an authentic instance because the medium is repeatable
D. It constitutes a direct forgery of the primary master cast

**Answer:** A. It lacks legitimacy purely because artist intent is missing

**Why:** Allographic works derive authenticity from the artist's sanction rather than singular physical execution. An unauthorised pull shares the identical material mould history, yet fails as an authentic work because it was produced outside the artist's explicit decision and limits.

Page: https://tryals.app/practice/sculpture-i/positives-and-the-multiple/a-cast-bronze-is-classed-as-allographic-rather-than-autographic-what

### 8. Arrange the stages of producing a cast positive in order.

**Answer:**

1. Check the mould is clean, dry and correctly assembled
2. Apply release agent if the material pair requires it
3. Mix the casting material to its stated ratio
4. Introduce it so that air can escape
5. Demould once set, then clean the seams

**Why:** The fourth step carries most of the failures. Pouring without a path for the air produces a cast with a region simply missing, and the fix is a vent, which has to be built into the mould long before this stage.

Page: https://tryals.app/practice/sculpture-i/positives-and-the-multiple/arrange-the-stages-of-producing-a-cast-positive-in-order

### 9. A cast bronze from a reusable mould is autographic in the same strict sense as a carved marble.

**Answer:** False

**Why:** **False.** A carved marble is autographic strictly: the object's history of production is part of the work, and a copy is a forgery. Several bronzes from one mould can be equally authentic, so "the original" becomes a question about **authorisation** rather than about matter, which puts the bronze much closer to the allographic side.

Page: https://tryals.app/practice/sculpture-i/positives-and-the-multiple/a-cast-bronze-from-a-reusable-mould-is-autographic-in-the-same-strict