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Patina formulas for copper, brass and bronze

The nice guys at The Science Company said we could reprint their patina recipes. Remember to spot test a small piece first, and don't come crying to us or to them if you're careless with your chemicals! Also, if you use a recipe, consider using them as a supplier to thank them for sharing.

1. Light to Dark Brown
2. Brown to Black
3. Blackish Brown
4. Florentine Brown
5. Antique Green
6. Basic Green
7. Blue Green
8. Cold Process Green
9. Light Green
10. Green
11. Purple to Light Green
12. Green-Blue (Flemish)
13. Transparent Blue
14. Blue
15. Straw Yellow
16. Golden Yellow
17. Deep Rust Red
18. Purple
19. Antique White
20. Red - semi-matt (For Copper & Copper Plate)
21. Dull Pink (For Copper & Copper Plate)
22. Red - Purple Satin (For Cast Bronze)
23. Orange Brown (For Cast Bronze)
24. Black - semi-gloss (For Cast Bronze)
25. Blue Green (For Cast Bronze)
26. Golden Yellow (For Cast Bronze)
27. Blue Green - semi-matt (For Cast Bronze)
28. Brown - Greenish Yellow (For Cast Bronze)
29. Reddish Brown (For Cast Brass)
30. Black (For Cast Brass)
31. Variegated Gold-Brown (For Cast Brass)
32. Red (For Cast Brass)

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).
  • 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
  • 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
  • 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. 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.

12. 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.

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 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.

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)

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)

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)

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)

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)

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)

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.

28. Brown - Greenish Yellow (for Cast Bronze)

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 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 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 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 Brass)

Ingredients

  • Cupric Nitrate... 8 oz
  • Oxalic Acid... 8 oz
  • Distilled Water... 1 gal

Process

Heat metal and apply hot liquid

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By Tom K at 12/29/2005 - 10:48pm | Blacksmithing HowTo/Troubleshooting: | Finishing