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"CitriSurf® is a perfect and environmentally friendly alternative to passivating with nitric acid!"

Dieter Fuchs, Boehringer Ingelheim Pharma GmbH & Co. KG


Stainless steel - rust removal and passivation: CitriSurf®77plus is a high quality blend of chemicals formulated for cleaning, rust removal and passivation of stainless steel products. It is provided in trigger sprayer bottles for applications where it is desired to spray the product on a local area. CitriSurf®77plus is specifically designed to provide a portable, low cost and efficient removal of contaminants and all rust and free iron from the surface of stainless steel, providing the highest chrome oxide levels possible.

Physical Properties
Specific Gravity 1.041
Viscosity 2 cps
Form Liquid*
Chemical Composition Citric acid, water, proprietary ingredients
Operating Temperature Room temp or higher
Flash Point None
Water solubility 99%
Normal working concentration Ready to use/Full strength
pH at working concentration ~ 1.6
Packaging 500 ml trigger sprayer bottles
20 Litre Canister
* The Gel-form Version with higher viscosity is availible as CitriSurf®2310.

Application Procedure

  1. To assure best results the parts or areas 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.
  2. The parts or areas to be cleaned and passivated should be sprayed, immersed or wiped with CitriSurf®77plus to completely wet the surfaces, especially in crevices or in areas where any rust or corrosion may have occurred. The surface must be soaked or left moist with the CitriSurf®77plus solution for a period of 15 to 30 minutes at room temperature. Difficult rust or corrosion must be tested to determine the exact best conditions for removal. If heavy rust needs to be removed, Scotch BriteTM or other non iron containing abrasive may be helpful. After soaking, rinse the surface with clean water. The surface can then be wiped dry with a clean cloth or appropriate absorbent medium. Allow the surface to air dry prior to use. CitriSurf®77plus will not harm most metal appliances or surfaces, and will enhance the brightness when used as directed.


The cleaning components of CitriSurf®77plus thoroughly remove all traces of oil and grease from the surface. The existing rust is loosened and can be mechanically removed. 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 application 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®77plus 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. Rubber or plastic gloves should be worn to apply the product to the surface or to wipe it dry. Do not apply CitriSurf®77plus to electrical wiring or other conductive material that is connected to electrical current without first turning off all electricity! CitriSurf® is a water based conductive material. Serious injury or death con occur from electrical shock. Do not leave concrete or carbon steel exposed to CitriSurf® for any period of time. Damage to these materials will occur with prolonged exposure.


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


CitriSurf®77plus should be stored at temperatures between 10 °C and 40 °C in the bottles supplied with the product. (If accidentally frozen, thawing will return product to normal.)

Technical Services

For technical assistance, please contact MKK GmbH.


CitriSurf®77plus 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.