Black Stainless Steel Oxide Liquid

Stainless Steel Blacks with Verzinkshop Black Stainless Steel Oxide Liquid

Verzinkshop Black Stainless Steel Oxide Liquid is the Black Stainless Steel Oxide concentrate, mixed ready-to-use at 1:3 (250 ml concentrate + 750 ml water), so you can immediately start chemically blackening stainless steel. The treatment gives an even gray to gray-black conversion coating without noticeable dimensional change. A sealer is optional and can be applied for extra protection or a specific look.

Suitable for stainless steel from the 400 series. For 300 series stainless steel, a stronger mixing ratio (1:2 or 1:1) is required — choose the concentrate for this.

Available in:

• 1 liter
• 2 liters
• 5 litres
• 10 litres
• 20 litres

Need a large quantity? Please contact us .

Blacken stainless steel with Verzinkshop Black Stainless Steel Oxide

• Liquid is ready to use – 1:3 (250 ml concentrate + 750 ml water).
• Application: Stainless steel 400 series. For stainless steel 300 series: use the concentrate.
• Treatment: dipping 2–5 minutes, swab/manual 1–3 minutes.
• Activate the surface: Verzinkshop Metal Activator or 30% hydrochloric acid (HCl) diluted 1:1 to 1:3 with water for 2–5 min, then rinse well. Alternative: warm citric acid for light activation/derusting (may be less effective on very passive stainless steel).
• Sealer optional (e.g. Galvanizing Acrylic Metal Sealer or Galvanizing DeepSeal Metal Sealer), apply immediately after rinsing if desired.
• Not for iron/carbon steel – use our solutions for steel/iron.

The color of stainless steel after chemical blackening

Ordinary steel or iron reacts quickly with chemicals such as Galvanizing Black Oxide, which produces a deep black finish. However, with stainless steel chemical blacks, the finish is usually gray to iridescent blue-black. This is because stainless steel contains chromium and nickel, which form a thin passive layer that prevents further oxidation.

This passive protective layer influences the way stainless steel reacts to black oxide products. This layer must be removed so that the metal can react with the black oxide products.

Stainless steel from the 300 series, such as 316, is particularly resistant to corrosion and oxidizes more difficult, so that the finish remains lighter. Stainless steel from the 400 series can get a darker finish due to the lower amount of chrome.

Activating stainless steel

Stainless steel naturally forms a dense chromium oxide layer that prevents further oxidation. This passive layer also blocks the reaction with black-oxide products. Activate removes that layer, allowing the surface to react evenly and giving you an even gray to gray-black finish (especially important with 300 series stainless steel).

Activation can be done in different ways:

• Chemically with the Verzinkshop Metal Activator. (good for stainless steel from the 400 series)

• With hydrochloric acid: use 30% hydrochloric acid (HCl) diluted 1:1 to 1:3 with water (2–5 minutes), then rinse well. (good for stainless steel from the 300 series)

• Mild alternative: warm citric acid for light activation/derusting (less powerful on strong passive stainless steel).

• Mechanical for large and flat surfaces that are easy to sand.

After activation, immediately blacken the object without letting it dry. The rust-inhibiting chromium oxide layer forms again as soon as stainless steel comes into contact with oxygen and moisture, often within seconds to minutes. This process can be accelerated by passivating with citric acid. During blackening, you want to prevent this repassivation between steps, so work “wet-in-wet” and continue treatment immediately after activation.

Frequently Asked Questions

• How long does the liquid last? For hobby use, usually several months in a sealed container. Performance depends on hygiene, load and maintenance.
• Can I use this on iron or steel? No. Use our iron/steel solutions: Black Oxide or Black Oxide Ultra.