Black Stainless Steel Oxide Concentrate

Stainless Steel Black with Verzinkshop Black Stainless Steel Concentrate

Stainless steel chemical blackening with Verzinkshop Black Stainless Steel Oxide Concentrate. The product offers a quick way to provide stainless steel with an even gray to gray-black finish. Blackening stainless steel with this product is simple and it is suitable for both small objects and larger surfaces such as furniture and panels. A sealer is optional and can be applied for extra protection or a specific look.

Available in:

• 125 ml makes 0.5 liters (tester)
• 250 ml makes 1 liter
• 500 ml makes 2 liters
• 1 liter makes 4 liters
• 2 liters makes 8 liters
• 4 liters makes 16 liters
• 8 liters makes 32 liters

Need a large quantity? Please contact us .

Most important properties of Black Stainless Steel Concentrate

• Standard dilute to 1:3 with distilled, demi or tap water. For difficult alloys, such as stainless steel from the 300 series, stronger mixing ratios are possible (e.g. 1:2 or 1:1) or undiluted. More about water choice.
• Suitable for stainless steel 300 and 400 series.
• Treatment: Dipping usually 2–5 minutes, swab/manual 1–3 minutes.
• Color strength depends on preparation, stainless steel type and contact time.
• Stainless steel usually needs to be activated for an even result. Read here how to do that.
• Coverage: depending on stainless steel type, preparation and method (1 to 2 m² per 250 ml of liquid mixed).

Features of Verzinkshop Black Stainless Steel Oxide Concentrate

• Professional product of high quality for blackening stainless steel at room temperature.
• Specially developed for stainless steel.
• To be used by immersion or manually (brush, sponge, cotton swab).
• No influence on the dimensions, suitable for precision parts.
• Operates at room temperature, light heating in cold environment is allowed if necessary.
• Not suitable for iron and carbon steel. For those materials: Black Oxide or Black Oxide Ultra.

Protecting Chemically Blackened Stainless Steel

A sealer is optional. Use a sealer for extra corrosion protection, color depth or desired shine.

• Electrolyte Acrylic Metal Sealer – clear, hard, thin acrylic finish, ideal for indoor use.
• Verzinkshop DeepSeal Metal Sealer – oil sealer, dust-dry, deepens the black.

Self Stainless Steel Chemical Blackening

• Light the Black stainless steel solution in a plastic or glass container. First, perform tests according to the manual.
• Degrease and clean thoroughly (no petroleum-based solvents).
• 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 or rust removal (may be less effective on very passive stainless steel).
• Soak for 2–5 min with light movement or apply manually (swab) for 1–3 min. For very passive surfaces, contact with ordinary steel in the bath (e.g. steel wire or hook) can help start the reaction.
• Rinse in a designated container. Do not dry with compressed air.
• Sealing (optional): apply a sealer immediately after rinsing if desired.

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 so that the surface can react evenly and you get an even gray to gray-black finish, especially important with 300 series stainless steel.

• 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 for 2–5 minutes, then rinse well (good for 300 series stainless steel).
• Mild alternative: warm citric acid for light activation or rust removal.
• 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.

Blackening of lightly rusted steel

Although this product has been specially developed for stainless steel, in some cases it can also be used to blacken slightly rusted steel using the swab method.

Clean and degrease the steel thoroughly, remove loose rust with a sanding pad or steel wool and apply the concentrate undiluted with a brush or sponge. Rub in lightly and let it react for a few minutes until an even blackening is visible, then rinse thoroughly with water and dry carefully.   If necessary, repeat the blacks.

For a more beautiful and durable result, we recommend using a sealer.

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 solutions for iron and steel: Black Oxide or Black Oxide Ultra.