A patina is a surface colour achieved through controlled chemical reactions on metal. In sculpture, patinas are applied using chemical solutions, heat and multiple coats to create colours from black to green to gold on bronze, copper and brass.

How do I estimate surface area?

For irregular sculptures, estimate by imagining the surface unfolded flat. A rough guide: surface area is approximately 3-4 times the largest cross-section area for organic forms. For more accuracy, use the Clay Weight Calculator to estimate volume and derive surface area.

How many coats of patina do I need?

Most patinas require 3-5 coats to build depth and consistency. Apply thin coats with heat between each application. Liver of sulphur works in fewer coats (2-3), while green patinas may need 5-8 coats over several days.

Do I need to seal the patina?

Yes — apply a clear wax (Renaissance wax or microcrystalline wax) after the patina has fully developed. This protects the surface and adds a subtle sheen. Outdoor sculptures may need lacquer instead of wax.

What safety equipment do I need?

Always wear chemical-resistant gloves, safety glasses and work in a well-ventilated area or outdoors. Some patina chemicals (cupric nitrate, ferric chloride) are toxic — use a respirator with acid gas cartridges. Keep neutralising solution nearby.

ArtCalcs

Patina Calculator — Chemical Patina Solutions

Calculate chemical patina solution quantities for metal sculpture finishing.

Surface Area

Estimate the sculpture surface

Number of Coats

Patina Type

How We Calculate This

How Patina Calculation Works

Total solution = Surface area x Application rate x Coats x 1.2 waste

Each patina chemical has a specific application rate per cm². The total solution volume is divided by the dilution ratio to determine chemical weight and water volume. A 20% waste allowance covers drips, testing and touch-ups.

Frequently Asked Questions

Related Calculators

Clay Weight Calculator

Estimate clay weight for solid or hollow sculptures. Covers earthenware, stoneware, porcelain and air-dry clay with shrinkage.

Armature Calculator

Calculate wire and rod lengths needed for sculpture armatures based on figure height, pose type and proportions. Free calculator.

Mould Volume Calculator

Calculate the volume of silicone, plaster, alginate or jesmonite needed to make a sculpture mould. Includes weight and cost estimates.

Plaster Mix Calculator

Work out the correct plaster-to-water ratio by weight for casting and mould making. Covers Plaster of Paris, Herculite and more.

Bronze Weight Calculator

Estimate bronze casting weight and material cost from wax model dimensions. Essential for planning lost-wax bronze sculpture.

Last updated: February 2026

All calculations are estimates. Always verify quantities before purchasing materials.