What is Patina?

What is Patina?

Patina is a thin layer that forms on the surface of copper, brass, bronze, and similar metals through oxidation or other chemical processes. This layer not only provides protective coverage against corrosion and weathering, but also adds aesthetic value through a unique, aged look.

Important note: Chemical finishes are not suitable for use on food contact items.

Patina Chemistry

The formation of patina on copper and its alloys is a fascinating chemical process. When copper is exposed to oxygen, various colors of patina naturally develop: from salmon pink to dark brown and finally to a characteristic green color. That green hue, known from the Statue of Liberty, among other things, consists of a mix of copper chlorides, sulfides, sulfates and carbonates, depending on the environmental conditions.

Patinating yourself

You can speed up patination with patina liquids from our webshop. This allows you to create a variety of finishes on copper, bronze and brass, among others. The process takes seconds to minutes, by dipping or by applying with a brush, sponge or cloth. You can combine different patinas on one object for special effects.

Antique patination and restoring old patina

Old patina layers on antique or other objects can easily be restored. Apply a patina concentrated or diluted topically with a brush or sponge. By varying the mixing ratio, you can get close to the original color or match it exactly.

Patina is also widely used on new objects such as lamps, clocks, pots, fittings and jewellery to give a unique, aged look.

How do you apply patina to copper, brass and bronze?

• Cleaning: clean and degrease the metal; Remove rust and contamination.
• Preparation: Prepare the surface with an acid or etching/activator, depending on the condition of the metal.
• Patinating: submerge the object or apply the liquid with brush/sponge/cloth for the desired effect.
• Rinse: rinse very thoroughly; Residues left behind can cause oxidation and discoloration.
• Finishing: Seal with Acrylic Sealer or DeepSeal oil sealer for protection and color retention.

Verzinkshop patina liquids

Verzinkshop supplies patinas in concentrate form for a variety of finishes on bronze, brass, copper and more. You dilute with water as desired for different color strengths and effects.

Brown Black Patina for bronze, copper and brass

Use the Brown Black Patina concentrate for rich antique brown-to-black finishes.

Chocolate Brown Patina for Bronze, Copper and Brass

The Brown Patina concentrate gives a deep chocolate brown antique finish.

Gunmetal Blue & Purple Patina (for copper, brass, bronze, white metals, silver and tin)

• Produces colors from gunmetal blue to light purple and from black to brown.
• On white metal, silver and tin/lead: brown.
• On copper, brass and bronze: grey to black and gunmetal blue to light purple.
• Product: Gunmetal Blue & Purple Patina.

Finish and protection

• Acrylic Sealer: water-based, very thin, dries satin to glossy; virtually invisible after drying; Ideal for indoors.
• DeepSeal Oil Sealer: oil-based, penetrates deep into pores, intensifies color, dries dust-dry and protects strongly against water and weather influences.

Safety and disclaimer

Caution: Always work with proper personal protective equipment and in a suitable, ventilated environment. Read the Safety Data Sheets (SDS) of all substances used.

Verzinkshop takes no responsibility for the recipes below and any damage due to misuse or typos. The formulas are purely informative, come from public internet sources and are not endorsed by Verzinkshop. Always assess for yourself whether a mixture is safe and suitable.

Patina formulas (overview as bullet lists)

Light brown to dark brown / Red to reddish brown

• Iron(III) nitrate: 7.5 ml
• Distilled water: 500 ml
• Process: Hot or Cold

Brown to black

• Liver of sulfur: the size of a grape (finely ground)
• Distilled water: 500 ml
• Process: hot or cold; Use a fresh solution every time

Blackish brown

• Iron(III) nitrate: 55 ml
• Liver of sulfur: 8 ml
• Distilled water: 500 ml
• Process: hot or cold; mixing in specified order

Florentine brown

• Ferric(III) chloride: 5 ml
• Iron(III) nitrate: 7.5 ml
• Distilled water: 500 ml
• Process: hot or cold; rich brown patina

Antique green

• Ammonium chloride: 10 g
• Copper(II) sulphate: 90 ml
• Distilled water: 950 ml
• Process: hot; solution 82–88°C, metal ±93°C; rinse cold at ±38°C; pour/dry/cool rinse and repeat

Basic green

• Copper(II) nitrate: 5 ml
• Distilled water: 500 ml
• Process: hot; semi-transparent; Heat metal and use a fresh mixture each time

Blue-green

• Sodium thiosulfate: 7.5 ml
• Iron(III) nitrate: 55 ml
• Distilled water: 950 ml
• Process: hot; solution 82–88°C, metal ±93°C; rinse cold at ±38°C; for yellow-green: dip in dilute nitric acid, rinse and dry

Cold process green

• Copper(II) nitrate: 40 g
• Ammonium chloride: 40 g
• Calcium chloride: 40 g
• Distilled water: make up to 1 litre
• Process: cold; opaque; frog green after repeated applications (intervals ±30 min); Combines well with brown/black patinas

Light green

• Sodium thiosulfate: 240 ml
• Iron(III) nitrate: 85 ml
• Distilled water: 4 litres
• Process: hot; solution and metal 60–71°C

Green

• Sodium thiosulfate: 240 ml
• Lead acetate: 85 ml
• Distilled water: 4 litres
• Process: cold; reportedly good on brass

Green – blue

• Sodium thiosulfate: 240 ml
• Lead acetate: 85 ml
• Distilled water: 4 litres
• Process: hot; 77–88°C; especially for brass

Purple to light green

• Sodium chloride: 5 parts (weight)
• Ammonium hydroxide: 4 parts (weight)
• Process: early purple; with additional applications/reaction to light green

Transparent blue

• Sodium thiosulfate: 60 g
• Concentrated nitric acid: 4 g
• Distilled water: 950 ml
• Process: transparent dip patina; preservative (wax or PU) required; Tap water can give a gray-blue tint

Blue

• Liver of sulfur: 15 g
• Ammonium chloride: 200 g
• Distilled water: 950 ml
• Process: Apply to the surface

Straw-colored

• Iron(III) nitrate: 7.5 ml
• Distilled water: 240 ml
• Process: Heating metal and applying hot liquid

Golden yellow

• Sodium thiosulfate: 7.5 ml
• Iron(III) nitrate: 55 ml
• Distilled water: 950 ml
• Process: heat solution to boiling point; Dipping

Deep rust red

• Copper(II) nitrate: 3.1 g
• Ammonium chloride: 3.1 g
• Calcium chloride: 1.3 g
• Copper(II) sulphate: 0.65 g
• Oxalic acid: 0.65 g
• Distilled water: 120 ml
• Nitric acid 10% (for post-processing)
• Process: wet application for color; then immerse for 30 min in 1:8 HNO₃:water; Rinsing and drying

Purple

• Sodium chloride: 5 parts (weight)
• Ammonium hydroxide: 4 parts (weight)
• Ammonium chloride: 5 parts (weight)
• Acetic acid (glacial acetic acid): 4 parts (weight)
• Distilled water: 32 parts (weight)
• Process: Apply to surface

Antique white

• Bismuth nitrate: 10 ml
• Distilled water: 240 ml
• Variants: pinch of sulfur liver, Iron(III) nitrate or Copper(II) nitrate for light color effect
• Process: Heating Metal, Applying Liquid

Formulas for specific metals

Red – semi-matte (for copper & copper plate)

• (A) Copper(II) sulphate: 25 g in 1 litre of demineralised water
• (B) Ammonium chloride: 7.5 g (add after first cooking step)
• Lawsuit:
  • 15 min of cooking in solution A
  • Adding Ammonium Chloride to A → A+B
  • 10 min cooking in A+B
  • Remove hot, rinse in hot water, dry

Matte pink (for copper & copper plate)

• Copper(II) nitrate: 5 ml
• Nitric acid 10%: 100 ml
• Distilled water: 1 liter (total)
• Process: hot immersion (60–71°C), ±5 min; rinse warm and let dry; Finishing with wax

Red-purple satin (for cast bronze and brass)

• Copper(II) sulphate: 25 g
• Distilled water: 1 liter
• Process: Boil in immersion 10–30 min; color starts red/orange after 2–3 min and deepens; hot rinsing; dry; Wash if desired

Orange-brown (for cast bronze and brass)

• Copper(II) acetate: 25 g
• Copper(II) sulphate: 19 g
• Distilled water: 1 liter
• Process: hot immersion (±80°C), ±15 min; rinse, dry, optional wash

Black – semi-gloss (for cast bronze and brass)

• Sodium thiosulfate: 50 g
• Iron(III) nitrate: 13 g
• Distilled water: 1 liter
• Process: hot immersion (60–70°C) ±20 min; colour transitions blue-purple → brown → grey; hot rinsing; Handle with care

Blue-green (for cast bronze and brass)

• Copper(II) sulphate: 20 g
• Copper(II) acetate: 20 g
• Ammonium chloride: 10 g
• Acetic acid 6%: add to a paste
• Process: apply paste for several days and let it dry; repeat daily; Washing and waxing after development

Golden yellow (for cast bronze and brass)

• Copper(II) sulphate: 50 g
• Ferrous sulphate: 5 g
• Zinc sulphate: 5 g
• Potassium permanganate: 2.5 g
• Distilled water: 1 liter
• Process: Cooking ±15 min; brush under warm water in between; repeat until desired effect; Finish with hot rinse, dry and wash

Blue-green – semi-matt (for cast bronze and brass)

• Copper(II) acetate: 20 g
• Ammonium chloride: 35 g
• Distilled water: 1 liter
• Process: Applying Liquid; drying/repeating for several days; Drying and waxing after development

Brown – greenish-yellow (for cast bronze and brass)

• Copper(II) nitrate: 80 g
• Nitric acid 10%: 100 ml
• Distilled water: 1 liter
• Process: hot immersion (60–70°C) for etching and darkening; 5 min; warm rinse; dry; Waxing

Reddish-brown (for cast bronze and brass)

• Copper(II) sulphate: 125 g
• Sodium acetate: 13 g
• Distilled water: 1 liter
• Process: cook 10–15 min; hot rinsing; dry thoroughly; Waxing

Black (for cast bronze and brass)

• Sodium thiosulfate: 6.3 g
• Iron(III) nitrate: 50 g
• Distilled water: 1 liter
• Process: hot immersion 50–60°C ±1 min; gradient purple → dark; hot rinsing; dry; Waxing

Varied golden brown (for cast bronze and brass)

• Potassium permanganate: 10 g
• Distilled water: 1 liter
• Process: hot immersion (±90°C) 3–5 min; gold luster forms quickly; rinsing hot → then cold; dry carefully; Waxing

Red (for cast bronze and brass)

• Copper(II) nitrate: 237 ml
• Oxalic acid: 237 ml
• Distilled water: 3.8 litres
• Process: Heating metal and applying hot liquid

Verde green

• Copper(II) sulfate: 8 parts (weight)
• Ammonium chloride: 4 parts
• Sodium chloride: 4 parts
• Zinc chloride: 1 part
• Acetic acid (glacial acetic acid): 3 parts
• Water: 128 parts
• Process: dip patina; repeat until color appears; sealer optional; more turquoise than green; can also be done with a brush

Peacock blue

• Sodium thiosulfate: 150 g
• Lead acetate: 25 g
• Tartar (potassium water stew tartrate): 30 g
• Water: 1 liter
• Process: intensely transparent; immersion 20–30 min; Seal immediately after drying

Yellow green

• Ammonium chloride: 7 parts (weight)
• Copper(II) acetate: 4 parts (weight)
• Water: 8 parts (weight)
• Process: cold; heavy opaque patina after multiple applications; Preservative optional