CitriSurf®

Passivating stainless steel with citric acid

CitriSurf® is a citric-acid-based cleaning and passivating solution for industrial applications. It safely and environmentally responsibly removes free iron from the surface of stainless steels and creates important conditions for corrosion-resistant, reproducible stainless steel surfaces.

The short path to the right solution

Physical property

Physical property
Specific gravity 1.1
Viscosity Thixotropic
State Viscous liquid
Chemical composition Citric acid, water and cleaning and passivation additives
Working temperature Room temperature up to max. 75° C
Flash point Non-flammable
Water solubility 99%
Normal working concentration Undiluted
Normal pH value ~4.0
Packaging units 20-litre plastic canister

The cleaning components of CitriSurf®2210 intensively remove all oil and grease residues from the surface. The special citric acid then removes the free iron ions from the upper molecular layers. This produces a positive change in the chromium-to-iron ratio, resulting in improved rust resistance or passivation of the surface. No impairment of the function of the passivated part is to be expected. Weld seams and solder joints are also not attacked, but are freed from contamination with free iron. Other materials, such as aluminium, can also be treated with CitriSurf® to remove iron components and iron-containing contamination introduced into the surface during machining. The stated concentrations and times refer to use on stainless steels. For other materials, special parameters must be developed through testing and/or in consultation with the developer or manufacturer of CitriSurf®.

Although the use of CitriSurf® is generally very safe, citric acid can cause skin irritation. Please refer to the safety data sheet for further information. During heating of the solution, cloudiness may occur. This disappears again after the heat source is switched off and is harmless for the function and the treated products.

CitriSurf® is not classified as dangerous goods and can be disposed of without difficulty in its delivered condition. However, during use, components may enter the solution that require special disposal. The relevant laws and statutory regulations for the disposal of liquids and chemicals must be observed. Please consult the responsible local authorities.

CitriSurf®2210 should be stored between 10° C and 70° C in stainless-steel or suitable plastic containers. If the solution freezes, it can be used normally again after thawing. During prolonged storage, the solution may crystallize; this effect is harmless and not damaging, and the crystalline components dissolve again when heated.

For further information on maintaining the finished passivation solution, please refer to the corresponding maintenance instructions. 

CitriSurf®2210, Gel

Stainless-steel passivation: CitriSurf®2210 is a high-quality product for cost-effective and efficient cleaning and passivation of stainless steels. It removes free iron from the surface of stainless steels. Its viscosity enables simple and safe application on surfaces, weld seams and large-area objects that cannot be passivated in an immersion bath. This process complies with the procedures for stainless-steel passivation described and required in the ASTM A-967 & AMS2700 standards.

APPLICATION

  1. To achieve the best results, the parts to be passivated must be thoroughly cleaned with a highly alkaline cleaner before treatment with CitriSurf®2210 to remove oil, dirt and lubricant residues. If this is not possible, mechanical cleaning should be carried out.
  2. All equipment such as containers, mixers, nebulizers, spray devices and hoses should be clean and dry before use. Only containers made of PP, PE or acid-resistant stainless steel (300 series) should be used for storing and transporting CitriSurf®.
  3. WARNING!!! Appropriate protective clothing, including safety goggles, should always be worn when using CitriSurf®2210. Further details can be found in the safety data sheet. Although CitriSurf® is much safer and less aggressive than other products, its components can cause slight skin irritation and may damage the eyes in case of direct contact.
  4. Do not apply CitriSurf®2210 to wires or cables that are still live. CitriSurf®2210 contains water and is conductive, and electric current can cause fatal injuries.
  5. Mix the solution well before use. Apply the solution generously and evenly to the surface. The exposure time is 10 to 30 minutes; afterwards, rinse the solution thoroughly from the surface. Repeat the process several times if necessary. Disposal must be carried out in accordance with local disposal regulations.
  6. After the final rinsing step, the workpiece should be allowed to dry sufficiently to complete the passivation process. Drying can be accelerated with a hot-air blower. Before further use or packaging, the workpiece must be completely dry.
  7. For even application of the gel, we recommend using a professional pressure sprayer.

Consulting & Contact

For many years, we have supported companies with stainless steel passivation, from root cause analysis through to implementation, including on site by arrangement.

How can CitriSurf® be ordered?

Exclusively from MKK GmbH, Oldenburg
Order by email: order@citrisurf.de

Please note:
- Provide your VAT ID
- Billing address and delivery address required
- Orders before 12:00 noon: usually shipped on the next working day
- Delivery date = shipping date (transit times depend on the logistics provider)