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"By using CitriSurf® I not only comply with the ASTM 967, but also to all environmental criteria!"

Peter Gremminger, August Reuchlen GmbH, Tuttlingen


CitriSurf®2250 is a high quality blend of chemicals formulated for the cleaning and passivation of stainless steel products.CitriSurf®2250 is specifically designed to provide low cost and efficient removal of contaminants and all free iron from the surface of most grades of stainless steel, including austenitic, ferritic, martensitic, and precipitation hardening, providing the highest chrome oxide levels possible.

Physical Properties
Specific Gravity 1.2
Density Concentrate: 1.216–1.226
20% dilution: 1.041-1.051
10% dilution: 1.018-1.028
Form Liquid*
Chemical Composition Citric acid, water, proprietary ingredients
Operating Temperature Room temp or higher (45–60 °C preferred)
Flash Point None
Water solubility Complete
Normal working concentration 10–20% by volume in water
pH at working concentration
pH value of the working solution
Packaging 20 liter plastic container. Larger sizes available upon request
*For automated processes, the reduced foam version CitriSurf®3250 should be used.

Application Procedure

  1. CitriSurf®2250 is an excellent cleaner by itself for many cleaning and passivation processes. However, to assure best results and help extend the life of the bath, the parts to be passivated may be cleaned with an appropriate cleaning solution prior to treatment with CitriSurf® solution, especially when heavy grease and oils are present. For grades containing high carbon, sulfur, or selenium, preclean using a good water based alkaline cleaner of pH ≥12 (see KleerKleen®4002). CitriSurf®- 2250 is an emulsifying cleaner. If you need to skim oils from the cleaning tank, this should be done with a separate cleaner prior to cleaning and passivation with CitriSurf®2250.
  2. All equipment, mixers, tanks and pumps should be clean and dry prior to mixing of CitriSurf® solution. CitriSurf®2250 should be mixed with clean water (deionized or distilled water if desired) at a ratio of 1 part of CitriSurf®2250 with 5 to 10 parts of water by volume to fill the tank used so as to adequately cover all parts to be treated. Polypropylene, stainless steel, or equivalents should be used for construction of all tanks and devices used in the CitriSurf® bath. Agitation of the solution in the tank is strongly recommended to attain optimum results. Air bubble agitation may produce excessive foaming (see CitriSurf®3250). Optimum results can be obtained with many parts by using CitriSurf® in an ultrasonic tank.
  3. Heat the solution for optimum performance. Teflon coated (or equivalent), stainless steel or titanium heating devices are recommended. Your tests should indicate the best bath working temperature for the products you manufacture. 45– 60°C is typical. Room temperature could be adequate depending on the end use.
  4. Completely immerse the parts to be passivated in the solution for a period sufficient to remove all free iron and contaminants from the surface. This is typically 5 to 20 minutes, depending on temperature, grade of stainless steel, hardness, use of ultrasonics, and the condition of the surface of the parts. This should be determined by testing with your product. Rinse the parts thoroughly with clean water, flowing water is optimum. DI water may be used to prevent water spotting. Dry completely in air immediately. Drying can be accelerated by use of a hot air oven or other drying medium to attain a highly passive surface.


The cleaning components of CitriSurf®2250 thoroughly remove all traces of oil and grease from the surface. The special citric acid then removes the free iron ions from the top molecular layers. This creates a positive change in the chrome-iron ratio which leads to a better rust resistance or passivation of the surface. There is no negative impact on the function of the passivated part. Welded seams and soldered joints are also not affected; they are only rid of impurities containing free iron. Even other materials such as aluminium can be treated with CitriSurf® in order to remove iron components and ferrous impurities which have been brought to the surface by mechanical processing. The specified concentrations and times refer to the use on stainless steel. For other materials, specific parameters must be developed by means of trials and/or consultation with the developer or manufacturer of CitriSurf®.

Notes on Use

Although very safe in normal use, CitriSurf®2250 is a Citric Acid based material, and as such it may cause irritation to exposed surfaces of the body. See Material Safety Data Sheet before using this material.


Dispose of according to all federal, state and local regulations.


CitriSurf®2250 should be stored at temperatures between 10°C and 70°C in 316 stainless steel or approved plastic containers (polyethylene or polypropylene). (If accidentally frozen, thawing will return product to normal.)

Care and Maintenance

Please see the relevant maintenance instructions for more details on maintaining the prepared passivating solution.

Technical Services

For technical assistance, please contact MKK GmbH.


CitriSurf®2250 meets all of the requirements of ASTM A-967 and AMS 2700 specifications.

Testing of your products with CitriSurf® before using in production is recommended. Every product and facility is different, and requires testing to ensure that CitriSurf® is compatible with the particular situation. No warranty is implied, or may be given in writing or verbally without the written permission of Stellar Solutions, Inc.