Patina Formulas for Brass, Bronze and Copper
Patinas of various color can be created by treating metal surfaces with chemical solutions. Copper, brass and bronze coatings are used for traditional decoration of many types of metalwork including gates, mailboxes, metal roofs, gutters, and, as shown here, fireplaces.
ScienceCompanyEXPRESS has collected these recipes from a variety of sources through the years. The formulas have not been personally tested so there is no guarantee that they will work. We suggest they be employed on a "trial and error" basis first so their effectiveness can be judged by the user.INDEX
Select coloring effect and learn how to create it with the formula.
1. Light to Dark Brown
Ingredients
- Ferric Nitrate... 1/2 tsp
- Distilled Water... 1 pint
Process
Heat metal and apply liquid. (Red to reddish brown has also been reported using this recipe.)
2. Brown to Black
Ingredients
- Sulfurated Potash grape sized lump (crushed).
- Ferric Nitrate... 1/2 tsp
- Distilled Water... 1 pint
Process
Hot or cold process. Use fresh solution each time.
3. Blackish Brown
Ingredients
- Ferric Nitrate... 2 oz
- Distilled Water... 1 pint
- Sulfurated Potash... 1/4 oz
Process
Hot process. Mix in the order given.
4. Florentine Brown
Ingredients
- Ferric Chloride... 1 tsp
- Ferric Nitrate... 1/2 tsp
- Distilled Water... 1 pint
Process
This old Italian formula produces a rich brown patina.
Apply evenly with a brush, sponge, or sprayer and let it dry. When a light brown rust color appears rinse well with cool water.
Dry with newspaper - it is very important to use newspaper. You may want to use a slightly damp paper.
Burnish the surface with steel wool or wire brushes. Leave over night
Repeat the process for darker result.
When finished, wax over the patina to darken and set the color.
5. Antique Green
Ingredients
- Ammonium Chloride... 1/3 oz
- Cupric Sulfate... 3 oz
- Distilled Water... 1 quart
Process
Hot process. Solution hot (180 to 190°F), metal hot (200°F), cold wash water applied after metal has cooled to around 100°F. Wash solution over metal surface, let dry, then wash piece in cool water. Repeat until color develops.
6. Basic Green
Ingredients
- Cupric Nitrate... 1 tsp
- Distilled Water... 1 pint
Process
Hot process, semi-transparent patina. Heat metal and apply a fresh mixture for each coloring.
7. Blue Green
Ingredients
- Sodium Thiosulfate... 1/4 oz
- Ferric Nitrate... 2 oz
- Distilled Water... 1 quart
Process
Hot process. Solution hot (180 to 190°F), metal hot (200°F), cold wash water applied after metal has cooled to around 100°F. Wash solution over metal surface, let dry, then wash piece in cool water. Repeat until color develops. For Yellow Green, dip in dilute nitric acid, then wash and dry.
8. Cold Process Green
Ingredients
- Cupric Nitrate... 40 gm
- Ammonium Chloride... 40 gm
- Calcium Chloride... 40 gm
- Distilled Water to make 1 liter
Process
A cold process, opaque patina. Frog green results after several applications, 1/2 hour intervals. Color is not satisfactory alone. Combines well with most brown and black cold process patinas.
9. Light Green
Ingredients
- Ammonium Chloride... 16 units
- Sodium Chloride... 16 units
- Cupric Sulfate (optional)... 16 units
- Ammonium Hydroxide... 16 units
Process
A cold process, opaque patina which should be applied at 12 hour intervals for several days. For deeper green add 16 units of cupric sulfate.
10. Green
Ingredients
- Sodium Thiosulfate... 8 oz.
- Lead Acetate... 1-3 oz.
- Distilled Water... 1 gal.
Process
A cold process that is said to work well on brass.
11. Green - Blue (Flemish)
Ingredients
- Sodium Thiosulfate... 8 oz.
- Lead Acetate... 1-3 oz.
- Distilled Water... 1 gal.
Process
Temperature at 170 to 190°F, a hot process especially for brass.
12. Purple to Light Green
Ingredients
- Sodium Chloride... 5 parts
- Ammonium Hydroxide... 4 parts
Process
Parts by weight. Early stages of this recipe produce purple. Additional applications and chemical action turn the metal light green.
13. Transparent Blue
Ingredients
- Sodium Thiosulfate... 60 gm
- Nitric Acid Concentrated... 4 gm
- Distilled Water... 1 quart
Process
A transparent, dip process patina. A preservative such as paste wax or polyurethane is necessary. May produce a grey blue when tap water is used.
14. Blue
Ingredients
- Sulfurated Potash... 15 gm
- Ammonium Chloride... 200 gm
- Distilled Water 1 quart
Process
Brush onto surface.
15. Straw Yellow
Ingredients
- Ferric Nitrate... 1/2 tsp
- Distilled Water... 1/2 pint
Process
Heat metal and apply hot liquid.
16. Golden Yellow
Ingredients
- Sodium Thiosulfate... 1/4 oz
- Ferric Nitrate... 2 oz
- Distilled Water 1 quart
Process
Heat solution to a boil. Dip.
17. Deep Rust Red
Ingredients
- Cupric Nitrate... 48 grains
- Ammonium Chloride... 48 grains
- Calcium Chloride... 20 grains
- Cupric Sulfate... 10 grains
- Oxalic Acid... 10 grains
- Distilled Water... 4 oz
- Nitric Acid 10%
Process
Brush to surface for color. Then dip into diluted (1 acid:8 water) Nitric acid for 1/2 hour, remove, wash and dry.
18. Purple
Ingredients
- Sodium Chloride... 5 parts
- Ammonium Hydroxide... 4 parts
- Ammonium Chloride... 5 parts
- Glacial Acetic Acid... 4 parts
- Distilled Water... 32 parts
Process
Parts by weight. Brush to surface.
19. Antique White
Ingredients
- Bismuth Nitrate... 2 tsp.
- Distilled Water... 8 oz.
Process
Heat metal and apply liquid. Variations of this formula add a pinch of Sulfurated Potash, Ferric Nitrate, or Cupric Nitrate for a slight coloring effect.
Formulas Suggested for Specific Metals.
20. Red - semi-matt (for Copper & Copper Plate)
Ingredients
- (A) Cupric Sulfate... 25 gm
- Distilled Water... 1L
- (B) Ammonium Chloride... 0.5 gm
Process
Boil immersion (A) 15 min.
Boil immersion (A)+(B) 10 min.
Immerse in boiling cupric sulfate solution about 15 min. or until color well developed.
Remove to hot water while ammonium chloride is added to the cupric sulfate solution. Then immerse about 10 min. Remove and wash in hot water. Dry and finish.
Important note: In general, chemically induced finishes are unsuitable for use on articles to be used with food.
21. Dull Pink (for Copper & Copper Plate)
Ingredients
- Cupric Nitrate... 1 tsp
- Nitric Acid 10% ... 100 ml
- Distilled Water... 1L
Process
Hot immersion - 5 min.
Immerse in hot solution (140-158°F, 60-70°C) which etches surface. Remove after 5 min., wash in warm water and air dry. Wax finish.
22. Red-Purple Satin (For Cast Bronze and Brass)
Ingredients
- Cupric Sulfate... 25 gm
- Distilled Water... 1L
Process
Boiling immersion (10 to 30 min.)
Immerse in boiling solution. A reddish orange color begins after 2-3 min. and deepens with continued immersion. When a reddish-purple color is attained from 10 to 30 min. remove and wash well in hot water. Dry and wax finish if choose.
23. Orange-Brown (For Cast Bronze and Brass)
Ingredients
- Cupric Acetate... 25 gm
- Cupric Sulfate... 19 gm
- Distilled Water... 1L
Process
Heat immersion (15 min)
Immerse in hot solution (176°F, 80°C). Color develops gradually and remove after 15 min. Wash and dry wax finish if choose.
24. Black - semi-gloss (For Cast Bronze and Brass)
Ingredients
- Sodium Thiosulfate... 50 gm
- Ferric Nitrate... 12.5 gm
- Distilled Water... 1L
Process
Hot immersion (20 min.)
Immerse in hot solution (140-158°F, 60-70°C). In one minute the surface is colored blue-purple. This recedes to a brown color, then changing to gray. After 20 min., remove, washing in hot water and dry in air. Handle as little as possible.
25. Blue Green (For Cast Bronze and Brass)
Ingredients
- Cupric Sulfate... 20 gm
- Cupric Acetate... 20 gm
- Ammonium Chloride... 10 gm
- Acetic Acid (6% soln.)... to form a paste.
Process
Applied paste - several days.
Using a mortar and pestle, grind ingredients to a creamy paste with the acetic acid. Apply paste to object with a soft brush giving a thick coating. Dry for one day. Wash dry residue away under cold water using a soft brush. Apply a thin layer of paste with a soft cloth and dry again for one day. Wash off residue again. Apply thin layer and dry until good variegated patina is achieved. When treatment completed, dry thoroughly. May be waxed.
26. Golden Yellow (For Cast Bronze and Brass)
Ingredients
- Cupric Sulfate... 50 gm
- Ferrous Sulfate... 5 gm
- Zinc Sulfate... 5 gm
- Potassium Permanganate... 2.5 gm
- Distilled Water... 1L
Process
Boiling immersion (15 min.)
Immerse object in boiling solution. A dark brown layer forms on surface after 1-2 min. Remove object and bristle-brush under hot water. Re-immerse and repeat process after 2 min. if necessary. Immerse again to approximately 15 min. remove and wash thoroughly in hot water using a bristle brush if necessary. Dry and wax finish of choice.
27. Blue Green - semi-matt (For Cast Bronze and Brass)
Ingredients
- Cupric Acetate... 20 gm
- Ammonium Chloride... 35 gm
- Distilled Water... 1 L
Process
Applied liquid.
With mortar and pestle, grind ingredients with a little water. Then add to remaining water. Dab and wipe on sparingly with soft cloth, to leave an evenly moist surface. Allow to dry in air. Repeat procedure once a day for several days as color develops. Dry for several days during which time the patina develops further. When there is no more surface change, wax to finish.
The most important part is to let it dry throughly between applications and up to two weeks before waxing.
28. Brown - Greenish Yellow (For Cast Bronze and Brass)
Ingredients
- Cupric Nitrate... 80 gm
- Nitric Acid 10% ... 100 ml
- Distilled Water... 1 L
Process
Immerse in hot solution (140-158°F, 60-70°C) to cause etching of the surface and gradual darkening. After 5 minutes remove and wash in warm water. Allow to air dry. When dry, wax finish.
29. Reddish Brown (For Cast Bronze and Brass)
Ingredients
- Cupric Sulfate... 125 gm
- Sodium Acetate... 12.5 gm
- Distilled Water... 1 L
Process
Boiling immersion (10-15 min)
The color will develop after 10 - 15 min. Remove and wash in hot water. Dry thoroughly, wax finish.
30. Black (For Cast Bronze and Brass)
Ingredients
- Sodium Thiosulfate... 6.25 gm
- Ferric Nitrate... 50 gm
- Distilled Water... 1 L
Process
Heat immersion - 1 minute.
When article is immersed in hot solution (120-140°F, 50-60°C) a succession of colors is produced. It changes to a purplish color after about 45 seconds. The color darkens quickly and the article is removed after about 1 minute. Wash thoroughly in hot water and air dry, wax finish.
31. Variegated Gold-Brown (For Cast Bronze and Brass)
Ingredients
- Potassium Permanganate... 10 gm
- Distilled Water... 1 L
Process
Hot immersion (3-5 min.)
Immerse in hot solution (194°F, 90°C). A golden lustre develops within one minute and becomes more intense. When lustre color is fully developed in 3 - 5 minutes, remove and wash in hot water, which is also a cooling process. Finally, wash article in cold water. Dry carefully first by blotting excess moisture with absorbant tissue paper and then air dry. Wax finish when dry.
32. Red (For Cast Bronze and Brass)
Ingredients
- Cupric Nitrate... 8 oz
- Oxalic Acid... 8 oz
- Distilled Water... 1 gal
Process
Heat metal and apply hot liquid
