CitriSurf®
Passivating stainless steel with citric acid
CitriSurf® is a citric-acid-based cleaning and passivation solution for industrial applications. It safely and environmentally responsibly removes free iron from the surface of stainless steels, creating important conditions for corrosion-resistant, reproducible stainless-steel surfaces.
Medical Technology
Passivating stainless steel for medical instruments, devices, implants, prosthetics and dental technology with citric acid
Stainless-steel parts for medical instruments, devices, implants, prosthetics and dental components often have to be freed from free iron and near-surface contamination after processing steps such as grinding, polishing or laser marking in order to reliably support corrosion resistance.
CitriSurf® 2250 BF is a biocide-free citric-acid-based passivation solution for medical technology applications. The process can be used within the passivation approaches described in ASTM A967 and AMS 2700; standards-compliant effectiveness is demonstrated through suitable testing and a validated process chain consisting of pre-cleaning, passivation, rinsing and drying.
Medical Technology
CS2250 and CS2250 BF: Specialized CitriSurf® Solutions for Medical Technology
CitriSurf® 2250 and CitriSurf® 2250 BF are specialized passivation solutions within the CitriSurf® product line. While CitriSurf® 2250 BF has been specifically developed for medical technology applications and is formulated without fungicides or other biocides, CitriSurf® 2250 is also suitable for a wide range of applications requiring high-quality stainless steel passivation. Both products promote the formation of a stable passive layer and contribute to excellent corrosion resistance.
This makes CS2250 and especially CS2250 BF well suited for manufacturers processing or finishing stainless steel components where, in addition to corrosion protection, the composition of the process chemistry is an important consideration.
Suitable for Medical Instruments, Devices, Implants and Prosthetics
CS2250 and CS2250 BF are particularly suitable for applications such as:
- Surgical and dental surgical instruments
- Medical devices and stainless steel components
- Implants, abutments, and implant-related or dental technology components
- Prosthetic components
- Precision components for medical systems
- Stainless steel parts with high requirements regarding surface quality and process reliability
- In many cases, martensitic stainless steels as well; high-carbon grades (e.g. 440C, 1.4021, 1.4034) may be critical and should be evaluated for the specific application
Laser marking with a fiber laser can alter the surface chemistry and oxide layer. Therefore, reliable passivation and subsequent testing are recommended. In such cases, free iron or other surface contaminants may reduce corrosion resistance. Passivation with CitriSurf® 2250 or CitriSurf® 2250 BF helps prepare the surface and supports the formation of a durable passive layer.
Especially in these areas, the stainless-steel surface can be influenced by manufacturing and further processing, for example by:
· machining, grinding or polishing
· thermal influences
· handling and transport
· residues from upstream processes
· laser marking and identification
Medical Technology
Why biocide-free is relevant in medical technology
Biocide-free here means: without added fungicides or other biocidal active substances for preserving the process chemistry; the application serves the passivation of stainless-steel surfaces and is not designed as a product with a primary biocidal function.
For medical-technology applications, this biocide-free formulation can help reduce potential residue risks from the process chemistry. Whether a component passes a biological evaluation, for example cytotoxicity according to ISO 10993-5 as part of the biological evaluation, depends on material, geometry, process parameters and validated pre-cleaning and rinsing, and must be tested for the specific application.
Typical use cases for CS2250 BF
After processing medical stainless-steel components: with instruments, device components, implants and prosthetic parts, processing steps can influence the surface. Passivation with CS2250 BF supports the removal of free iron and targeted surface preparation.
After marking and laser marking: especially in medical technology, markings and traceability are important parts of production. After such process steps, downstream passivation can be useful to specifically support surface quality and corrosion resistance.
For sensitive applications with special requirements for process chemistry: where production requires a biocide-free passivation solution, CS2250 BF is the obvious CitriSurf variant.
Medical Technology
What requires special attention with CS2250
CS2250 requires highly alkaline pre-cleaning.
For pretreatment, CitriSurf offers KleerKleen™ 4002, an alkaline pre-cleaner matched to passivation. The product is intended as a concentrate for cleaning and pretreating stainless steel before passivation and was optimized to support the effect of the CitriSurf product line.
For medical-technology applications, this means that good results do not depend solely on the passivation medium, but on a well-coordinated process chain consisting of:
· highly alkaline pre-cleaning
· passivation with CS2250
· thorough rinsing
· controlled drying
· application-specific testing
FAQ
Frequently asked questions
Passivation aims to remove free iron contamination from the surface and support a cleaner, more corrosion-resistant surface. The prerequisite is a clean, contamination-free surface, if necessary with upstream cleaning/pickling.
In industrial environments, ASTM A967 and AMS 2700 are widely used references; ASTM A967 covers both nitric and citric treatments. The decisive factor is that the required effectiveness tests are passed.
ASTM A967 provides for various test practices, including high humidity, salt spray and copper sulphate tests. Which test is suitable depends on the component and the specification.
Biocide-free means that no fungicidal/biocidal additives are used, which can be an advantage in the context of sensitive medical-technology processes and possible residue considerations. Suitability must nevertheless be validated for each application.
In practice, citric acid is often used to remove iron contamination; repassivation then occurs through contact with oxygen. Some technical descriptions emphasize that citric acid primarily acts as acidic cleaning, while standards list citric procedures as passivation methods. Precise terminology is therefore important.
Medical Technology
Consulting on CS2250 for medical technology
Whether surgical instrument, device component, implant or prosthetic component: in sensitive medical applications, passivation should always be matched to material, component geometry, upstream processes and testing requirements.
We support you in selection and process design for CitriSurf® 2250 BF, especially for questions about:
· suitability for medical instruments and devices
· use with implants and implant-related components
· biocide-free passivation
· highly alkaline pre-cleaning
· rinsing and post-treatment
· integration into existing production processes
Consulting & Contact
Would you like to passivate medical instruments, devices, implants, or prosthetic components made of stainless steel using a biocide-free specialty solution designed for the medical technology industry? If so, please contact us to discuss your application and the use of CitriSurf® 2250 BF.
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)