How Do You Make Porcelain?: A Master Ceramicist's Complete Guide to Creating Fine China

Slip Casting Porcelain Body Formulation

Designed for fast mould fill, clean drain, and smooth surface finish. This body excels in hollowware and fine detail reproduction.

Peter Holland Industrial Slip Casting Body:

• Grolleg Kaolin: 35%
• Potash Feldspar: 25%
• Silica (Quartz): 20%
• Ball Clay (SGP or equivalent): 15%
• Bentonite: 0.5%

Stage 2: Forming Methods

There are three primary ways to give porcelain its form within the context of a professional production run.

1. Creating a Master Sculpture (Modelling)

For fine art, figurines, and repeatable commercial designs, the first step is to create a master sculpture or model. Crucially, this master is not sculpted from porcelain clay itself. Instead, it is crafted from a specialty industrial stoneware clay designed for high-precision modelling. The sculptor/modeller works with this clay to create the final form, which will then be passed to the specialist block & case maker, who then passes his blocks, moulds and cases onto the slip casters (see 3. below).

2. Jiggering & Jollying (Industrial Flatware)

This automated process is the standard method for producing thousands of identical plates and saucers. A plastic, solid porcelain body is used. A lump of clay is placed on a rotating plaster mould, and a profile tool is lowered to shape the piece to a precise thickness and diameter. It is a highly efficient production method that requires the porcelain to be in a solid, plastic form. Jiggering is the term used for making flatware like plates, while jollying is used for simple hollowware like bowls. By contrast, cups, which are a form of hollowware, are usually made using the slip-casting process (below). The cup body is formed by pouring liquid clay slip into a two-part plaster mould, and the handle is a separate component that is also cast in a mould and then attached to the cup.

3. Slip-Casting Process (Industrial Hollowware)

Slip-casting is the primary production method for hollow items, such as vases, teapots, and figurines. This technique uses a porcelain slip, which is the liquid form of the clay body.

• Slip Preparation: Mix clay body with 35-40% water plus 0.3% sodium silicate deflocculant
• Pouring: Fill plaster moulds and allow 15-45 minutes for desired wall thickness
• Draining: Pour excess slip out when walls reach 3-6mm thickness
• Demoulding: Remove when leather-hard (1-3 hours depending on form)

Stage 2.5: Blocking & Casing For Master Mould Production (Block & Case)

For any production run exceeding 20-30 pieces, the blocking stage becomes essential. This is where the ceramic industry transitions from individual craftsmanship to systematic production, a process that separates amateur pottery from professional ceramics manufacturing.

In block and casing, a silicone mould is immediately taken of the master mould so that new moulds can be made at will.

The Blocking & Case-Making Role

This is one of the most important stages of commercial 'How Do You Make Porcelain'. Once you have your master piece (whether wheel-thrown, hand-built, or sculpted), a specialist craftsperson called a blocker takes over. The blocker's job is to prepare the master for production casting by creating a series of moulds that can recreate the original form repeatedly. He also makes a silicone case (a mould of the plaster mould) so as to be able to make new plaster mould indefinitely for production runs.

Master Preparation Process:

• Assessment and Sectioning: The blocker examines the master piece to determine optimal mould lines where the plaster mould will split to allow casting and removal of greenware.
• Surface Preparation: The master is sealed and prepared to ensure clean mould release and prevent plaster adhesion that would damage the original.
• Initial Plaster Mould Creation: The first working moulds are made directly from the master using fine plaster of Paris, creating precise negative impressions.

[Visual Cue: Professional blocker's hands working on sectioning a master piece, showing the precise knife work required to determine mould lines]

The Two-Stage Mould System

Here's where the production stages of 'how do you make porcelain' reveals its sophistication:

Stage 1: Working Moulds (Plaster of Paris)

• Made directly from the master piece
• Used for actual slip-casting production
• Lifespan: Approximately 20-25 castings before wear compromises quality
• Material: Fine casting plaster for sharp detail reproduction

Stage 2: Cases: Master Blocks (Silicone Rubber)

• Now made from silicone rubber (in times past plaster-of-paris), which is the premium material for reproduction moulds as it doesn't break, chip, and lasts for many years. This process is known as 'case making', and is part of the blocker's job. This they are known as 'Blockers & Casers'.
• Created from the first perfect working moulds
• Purpose: Template for creating new working moulds as originals wear out
• Lifespan: Hundreds of reproductions over many years

The Production Cycle

Initial Setup:

• Blocker creates 2-3 perfect working moulds from master
• Immediately creates silicone master blocks from these moulds
• Production begins using original plaster working moulds

Ongoing Production:

• After every 20 castings, working moulds show wear (loss of detail, rough surfaces)
• New working moulds are cast from the silicone master blocks
• Master blocks remain pristine, ensuring consistent quality across hundreds of production runs

Professional Blocking Techniques

Critical Measurements:

• Shrinkage Calculation: Master forms must account for 12-16% total shrinkage (clay drying + firing). For example, the fine china brands I worked with usually wanted an 8.5 inch high finished fired figurine piece. This meant I had to know the exact shrinkage of their clay slip, because each factory was different, so that I could do the maths and work out the master's modelling height before shrinkage.
• Draft Angles: Slight tapers built into vertical walls for easy mould release. If this is not considered, then 'undercuts' will stop the cast coming out of the mould. Undercuts in sculpting the master are a primary consideration.
• Wall Thickness Consistency: Achieved through careful slip-casting timing rather than mould design.

Quality Control:

Every new working mould cast from master blocks undergoes dimensional checking against the original master. Professional potteries maintain tolerance standards of ±2mm for most applications.

Expert Insight: I've worked with blockers who can section a complex figurine for slip-casting with surgical precision. Their understanding of clay behaviour, mould release angles, and production efficiency often determines whether a ceramic design succeeds commercially or fails in production. All blockers are not created equal. Some are more sought after than others, and they, like me, tend to be collaborators with the big brands rather than employees. I have always said that best blockers are at least as highly skilled as master sculptors, just with a different skill set.

Economic Importance

The blocking stage represents a significant investment per design - sometimes on the thousands for a complex lady figurine - depending on complexity, but even then, this enables production economics that make fine porcelain commercially viable if the editions are high enough. Professional ceramic block moulds last for many thousands of casting cycles when properly maintained. For example, my figurine 'Tara' Celtic Princess had an edition of 7500 units and sold out within months at a retail price of £225 in 1998, generating £1.7 million turnover - thus justifying the huge cost of development and colour supplement advertising

Without this system, every piece would require individual hand-forming, making porcelain tableware and decorative objects prohibitively expensive. The blocking process is what enabled the democratization of fine porcelain from exclusively aristocratic luxury to middle-class accessibility.

Production Planning Note:

Factor blocking costs and timeline (typically 3-5 weeks) into any production run planning. The initial investment pays dividends through consistent quality and efficient production scaling.

This section explains the crucial production bridge between individual craftsmanship and manufacturing scale, something that differentiates professional ceramic knowledge on how do you make porcelain. The blocking stage is where art meets industry, enabling the beautiful porcelain we see in shops worldwide.

If you need further information about this important technical aspect of 'how do you make porcelain', the University of Staffordshire run courses specifically on this - see University of Staffordshire Ceramic Workshops

Stage 3: Drying - The Critical Phase

Porcelain's high shrinkage rate (12-16% from wet to fired) makes controlled drying essential:

Greenware Stage (40-50% moisture):

Figurine- Greenware

• Cover pieces with plastic, creating small air gaps
• Rotate pieces daily to ensure even drying
• Duration: 3-7 days depending on thickness and ambient conditions

Leather-Hard Stage (15-20% moisture):

• Ideal for trimming and attachment work
• Clay has firmness but retains some flexibility
• Final shaping and detail work completed here

Bone-Dry Stage (0-2% moisture):

• Pieces become chalk-white and extremely fragile
• Ready for bisque firing
• Any remaining moisture will cause explosive failure in the kiln

Stage 4: Bisque Firing - The First Transformation

Bisque firing converts fragile greenware into durable, porous ceramic ready for glazing.

Temperature Schedule:

• Heating Rate: 50°C/hour to 500°C (slow water smoke period)
• Critical Phase: 450-600°C - remaining moisture converts to steam
• Final Temperature: 950-1000°C
• Total Time: 12-16 hours including cooling

Physical Changes During Bisque:

• 0-100°C: Surface moisture evaporates
• 100-200°C: Mechanical water driven off
• 450-600°C: Chemical water removed from clay structure
• 573°C: Quartz inversion - critical heating/cooling point
• 950°C: Clay particles begin sintering

Post-Bisque Testing: Properly bisqued porcelain should absorb water readily when dipped, indicating successful pore structure for glazing. A great tip from the pros on how do you make porcelain.

The bisque stage

Stage 5: Glazing - The Glassy Coating

Porcelain glazes differ significantly from stoneware glazes in both composition and application.

Glaze Composition Basics:

• Silica: 45-65% - glass former
• Alumina: 8-15% - provides durability and prevents running
• Fluxes: 20-35% - lower melting temperature to match clay body

Application Methods:

• Dipping (Preferred Method):
• Clean bisque of dust with damp sponge
• Immerse piece smoothly for 3-5 seconds
• Lift vertically, allowing excess to drain
• Clean foot immediately with damp sponge

• Spraying (Production Method):
• Ensures even coating on complex forms
• Requires spray booth for safety
• Build up thin, multiple coats rather than single thick application

Critical Glazing Rules:

• Foot Cleaning: Always remove glaze from kiln contact points
• Thickness: Aim for 1-2mm glaze thickness because too thin causes crawling, too thick causes running
• Dust Prevention: Fire within 24 hours of glazing when possible

Stage 6: Glaze Firing - The Final Transformation

The glaze firing pushes porcelain to its physical limits, creating the vitrified ceramic we recognize.

The beauty of glazed porcelain

Firing Schedule:

• Initial Heating: 100°C/hour to 1000°C
• Critical Zone: 1000-1300°C - slow heating allows glaze/body interaction
• Final Push: 80°C/hour from 1300°C to final temperature
• Peak Temperature: 1320-1380°C for most porcelain bodies
• Soaking: Hold peak temperature for 15-30 minutes
• Cooling: Natural cooling to 1000°C, then can be accelerated

The Vitrification Process:

At peak temperature, three simultaneous transformations occur:

• Glaze Maturation: Glaze components flux completely, forming smooth glass coating
• Body Vitrification: Feldspar melts, fusing silica particles into glassy matrix
• Interface Bonding: Glaze and body chemically bond, creating integral structure

Temperature Monitoring: My expert colleagues use pyrometric cones exclusively for porcelain firing. Electronic controllers can fail; cones never lie about the actual heat work experienced by your pieces.

Professional Tips and Troubleshooting

Common Issues and Solutions

Cracking Problems:

• S-Cracks in throwing: Clay too soft or throwing too aggressively
• Rim cracks: Uneven wall thickness or too-rapid drying
• Firing cracks: Temperature rise too rapid or clay body/glaze expansion mismatch

Glazing Defects:

• Crawling: Dust or oils on bisque surface before glazing
• Pinholing: Glaze too thick or firing too rapid in critical zone
• Color variation: Uneven glaze application or kiln atmosphere fluctuations

Warping Issues:

• Foot warping: Uneven foot thickness or improper kiln support
• Body warping: Uneven wall thickness or too-rapid temperature changes

Advanced Techniques

Translucency Maximization:

• Use finest particle-size feldspar available
• Minimize iron content in all raw materials
• Fire to full maturity; under-firing reduces translucency dramatically

Strength Optimization:

• Add 10-15% grog to reduce thermal shock susceptibility
• Maintain silica content above 20% for structural integrity
• Consider slow cooling schedule to develop favourable crystal structure

Safety Considerations

Health Hazards:

• Silica Dust: Always wear N95 respirator when handling dry materials
• High Temperature: Kiln operation requires proper ventilation and protective equipment
• Chemical Exposure: Many glazes contain toxic metals so use appropriate protective measures

Workshop Safety:

• Install adequate ventilation system
• Maintain first aid supplies specific to ceramic injuries
• Never fire kilns unattended during critical temperature phases

Frequently Asked Questions

Q: How long does it take to make porcelain from start to finish?

A: Minimum 3-4 weeks for a simple piece: 1 week clay preparation and aging, 3-5 days forming and initial drying, 1 week final drying, 1 day bisque firing, 1 day glazing, 1 day glaze firing, plus cooling time.

Q: Why is porcelain so much more difficult than other clays?

A: Porcelain has low plasticity, high shrinkage, and narrow firing range. Its "short" working characteristics mean it tears rather than stretches, requiring completely different handling techniques.

Q: Can I make porcelain without a kiln capable of high temperatures?

A: No. True porcelain requires vitrification temperatures above 1300°C. Lower-temperature "porcelain-like" bodies exist but lack porcelain's defining characteristics.

Q: What's the difference between hard-paste and soft-paste porcelain?

A: Hard-paste porcelain (true porcelain) fires above 1300°C and achieves complete vitrification. Soft-paste porcelain contains glass cullet or bone ash, fires at lower temperatures, but lacks true porcelain's strength and translucency.

Q: How do I achieve the translucency porcelain is famous for?

A: Use finest-grade raw materials, maintain thin wall sections (2-4mm), fire to full maturity, and minimize iron contamination throughout the process.