Chromium Plating Solution Overview: Composition, Standards, and How It Benefits Industrial Projects

Types of Chromium Plating Solutions

Chromium plating solutions are essential in industrial surface finishing, offering enhanced durability, corrosion resistance, and aesthetic appeal. These solutions vary significantly in composition, safety, and application. Understanding their differences helps manufacturers choose the right plating method based on performance requirements, environmental compliance, and operational safety.

Hexavalent Chromium Plating Solution

The most widely used traditional method, known for its brilliant finish and high-performance coatings.

Advantages

• Premium bright, mirror-like finish
• Superior corrosion and wear resistance
• Excellent adhesion and coating uniformity
• Well-established industrial process with predictable results

Limitations

• Highly toxic and carcinogenic
• Strict environmental and safety regulations required
• Expensive waste treatment and disposal
• Banned or restricted in many regions (e.g., EU RoHS)

Best for: Decorative plating, aerospace components, legacy industrial applications where regulations permit

Trivalent Chromium Plating Solution

A modern, eco-friendly alternative with significantly reduced health and environmental risks.

Advantages

• Lower toxicity and non-carcinogenic
• Easier waste management and regulatory compliance
• Improved worker safety and reduced ventilation needs
• Comparable reflectivity and corrosion resistance to hexavalent chrome (with modern formulations)

Limitations

• Slightly less bright finish than hexavalent chrome
• More sensitive to bath contamination
• Higher initial setup cost for plating systems
• Limited compatibility with some legacy equipment

Best for: Automotive trim, consumer electronics, medical devices, and environmentally conscious manufacturing

Chromium Acid Plating Solution

Used primarily for hard chromium plating, delivering thick, functional coatings for high-stress applications.

Advantages

• Produces extremely hard, wear-resistant deposits
• Excellent for rebuilding worn or undersized parts
• High fatigue strength and low coefficient of friction
• Widely used in precision engineering and tooling

Limitations

• Typically contains hexavalent chromium (environmental concerns)
• Requires precise control of temperature, current density, and acid concentration
• High energy consumption
• Risk of hydrogen embrittlement in high-strength steels

Best for: Hydraulic rods, piston shafts, molds, and heavy-duty industrial components

Chromic Acid Plating Solution

A traditional formulation based on chromic acid (CrO₃) and sulfuric acid, used for electrodeposition of chromium.

Advantages

• Proven technology with decades of industrial use
• Capable of producing thick, durable coatings
• Good resistance to abrasion and chemical exposure
• Effective for both decorative and functional plating

Limitations

• Contains hexavalent chromium (health and environmental hazards)
• Low cathode efficiency (10–20%)
• Produces hazardous fumes requiring ventilation
• High operational and compliance costs

Best for: Aerospace landing gear, military hardware, and applications requiring extreme durability

Penetrating Chromate Conversion Coatings

Not a plating solution per se, but a surface treatment that enhances corrosion resistance through chemical conversion.

Advantages

• Forms a self-healing protective layer
• Excellent adhesion for paints and primers
• Effective on aluminum, zinc, and magnesium alloys
• Water-soluble polymer additives improve durability and delamination resistance

Limitations

• Provides thinner coating compared to electroplating
• Not suitable for load-bearing surfaces
• Hexavalent versions pose environmental risks
• Trivalent versions may offer slightly reduced performance

Best for: Automotive undercarriages, marine hardware, outdoor equipment, and corrosion-prone environments

Type	Toxicity Level	Corrosion Resistance	Finish Quality	Primary Use Case
Hexavalent Chromium	Very High	Excellent	Excellent (mirror finish)	Decorative & functional plating
Trivalent Chromium	Low	Very Good	Very Good (near mirror)	Eco-friendly manufacturing
Chromium Acid	High	Excellent	Fair to Good (matte/functional)	Hard plating, wear resistance
Chromic Acid	High	Excellent	Good to Excellent	Industrial & aerospace components
Penetrating Chromate	Low to High (depends on type)	Very Good	Poor (non-decorative)	Corrosion protection & priming

Expert Tip: When transitioning from hexavalent to trivalent chromium plating, ensure thorough cleaning of tanks and equipment to avoid cross-contamination, which can destabilize the trivalent bath and reduce coating quality.

Key Features of Chromium Plating Solution

Chromium plating solutions are widely used in industrial and consumer applications due to their exceptional ability to enhance the performance, longevity, and visual appeal of metal components. The electroplating process deposits a thin layer of chromium onto a substrate, creating a surface that combines functional benefits with aesthetic refinement. Below is a comprehensive overview of the most significant features that make chromium plating a preferred choice across multiple industries.

1. Superior Corrosion Resistance

One of the most critical advantages of chromium plating is its outstanding resistance to corrosion. When exposed to air, chromium naturally forms a dense, invisible oxide layer on its surface. This passive film acts as a protective barrier, effectively shielding the underlying metal from moisture, oxygen, and corrosive chemicals such as salts and acids.

This inherent protection makes chromium-plated components ideal for use in harsh environments, including outdoor installations, marine applications, and high-humidity zones. Common applications include automotive trim, fasteners, hydraulic rods, and agricultural equipment. By preventing rust and material degradation, chromium plating significantly extends service life and reduces maintenance costs, offering long-term economic and operational benefits.

2. Exceptional Durability and Wear Resistance

Chromium is one of the hardest metals used in industrial coatings, with a Mohs hardness rating of approximately 8.5–9. This extreme hardness translates into excellent resistance to abrasion, scratching, and mechanical wear. During the electroplating process, the chromium layer bonds metallurgically with the substrate, ensuring a durable and cohesive finish that resists chipping and flaking.

These properties are particularly valuable in high-friction environments where moving parts are constantly in contact—such as piston rods, shafts, gears, and machine tools. The wear-resistant surface reduces material loss over time, maintains dimensional accuracy, and minimizes downtime for repairs. As a result, industries ranging from aerospace to heavy machinery rely on chrome plating to improve component reliability and extend equipment lifespan.

3. High Aesthetic Appeal and Surface Finish

Beyond its functional strengths, chromium plating is renowned for its brilliant, mirror-like finish. The polished surface reflects light with a lustrous, silvery sheen that resembles polished stainless steel or sterling silver, making it highly desirable for decorative and consumer-facing applications.

This visual appeal enhances the perceived quality of products, contributing to brand image and customer satisfaction. Chrome plating is extensively used in automotive trim, motorcycle parts, bathroom and kitchen fixtures, furniture hardware, and electronic enclosures. Its ability to maintain shine and resist tarnishing over time ensures lasting beauty with minimal upkeep, adding both value and elegance to finished goods.

4. Enhanced Chemical Resistance

Chromium plating provides robust protection against a wide range of chemical agents, including strong acids, alkalis, solvents, and cleaning agents. The inert nature of the chromium oxide layer prevents chemical penetration and substrate degradation, even under prolonged exposure.

This makes chrome-plated components essential in chemical processing plants, pharmaceutical manufacturing, food processing equipment, and laboratory instruments. In these environments, maintaining material integrity is crucial to prevent contamination, ensure safety, and comply with hygiene standards. The chemical stability of chromium plating supports reliable operation in aggressive industrial atmospheres where other coatings might fail prematurely.

5. Functional Restoration and Dimensional Enhancement

In addition to protection and aesthetics, chromium plating plays a vital role in component repair and reconditioning. Worn or undersized parts—such as shafts, cylinders, and hydraulic rods—can be rebuilt to their original specifications through precision chrome plating.

The process allows for controlled deposition of chromium, enabling engineers to restore dimensional accuracy and surface smoothness without replacing entire assemblies. This capability is especially beneficial in maintenance-heavy industries like mining, oil and gas, and manufacturing, where unplanned downtime is costly. By extending the life of critical components, chromium plating supports sustainability, reduces waste, and delivers significant cost savings over time.

Feature	Industrial Benefit	Common Applications
Corrosion Resistance	Extends component life in humid, salty, or corrosive environments	Automotive parts, marine hardware, outdoor fixtures
Wear & Abrasion Resistance	Reduces friction damage and maintains precision tolerances	Machine tools, piston rods, gears, bearings
Aesthetic Finish	Enhances product appeal and brand perception	Trim, faucets, decorative hardware, consumer electronics
Chemical Resistance	Protects against acids, alkalis, and industrial solvents	Chemical reactors, processing equipment, lab instruments
Dimensional Restoration	Enables repair of worn parts without replacement	Hydraulic cylinders, shafts, industrial machinery

Important Note: While chromium plating offers numerous advantages, proper application and safety protocols are essential. Hexavalent chromium (Cr(VI)), commonly used in traditional plating baths, is toxic and regulated due to environmental and health concerns. Many industries are transitioning to trivalent chromium (Cr(III)) processes, which are safer and more eco-friendly. Always ensure compliance with local environmental regulations and use appropriate protective equipment during plating operations.

How to Use Chromium Plating Solution

Chromium plating is a widely used electroplating process that enhances the surface properties of metal components, providing improved corrosion resistance, wear resistance, and a highly reflective, decorative finish. Proper application of chromium plating solution requires careful preparation, precise control of electrical parameters, and adherence to safety protocols. Below is a comprehensive, step-by-step guide to ensure optimal results and workplace safety.

1. Preparation of the Workpiece

Surface cleaning is critical to ensure strong adhesion and uniform plating. Any contamination can lead to poor coating quality, blistering, or peeling.

• Remove rust, old paint, oxides, and prior coatings using mechanical methods such as wire brushing, sandblasting, or media blasting.
• Clean the surface thoroughly with a degreasing solvent or industrial alkaline cleaner to eliminate oils, grease, and dirt.
• Rinse the workpiece with clean water or distilled water to remove cleaning residues.
• Ensure the workpiece is completely dry before immersion in the plating bath—moisture can introduce impurities and disrupt the electrochemical process.

Pro tip: For high-precision applications, consider using ultrasonic cleaning for deep contaminant removal from complex geometries.

2. Setting Up the Plating Bath

The plating bath serves as the electrolytic medium where chromium deposition occurs. It must be prepared and maintained under controlled conditions.

• Use a chemically resistant tank (typically PVC or lined steel) to hold the chromium plating solution.
• Mix the chromium solution (usually chromic acid and sulfuric acid) strictly according to the manufacturer’s specifications—typically in a ratio of 100:1 (chromic acid to sulfuric acid).
• Maintain the solution concentration and temperature (usually between 45–65°C or 113–149°F) for consistent results.
• Ensure proper ventilation or use a fume hood, as chromic acid emits toxic hexavalent chromium fumes.
• Wear appropriate PPE: chemical-resistant gloves, face shield, goggles, and an apron.

Safety note: Hexavalent chromium is a known carcinogen. Always follow OSHA and EPA guidelines for handling, storage, and disposal.

3. Connecting the Electrodes

Electroplating relies on a direct current (DC) circuit to deposit chromium ions onto the workpiece surface.

• Use lead or lead-antimony alloy anodes (not stainless steel, which can degrade in chromic acid).
• Connect the anode to the positive terminal (+) of the DC power supply.
• Attach the workpiece (cathode) to the negative terminal (–), ensuring a secure electrical connection—often via a copper or titanium hook.
• Immerse both electrodes fully into the plating solution, maintaining even spacing for uniform current distribution.

Key consideration: Poor electrical contact can result in patchy or incomplete plating.

4. Controlling Power Supply Settings

Current density and voltage are critical factors that determine plating quality, thickness, and appearance.

• Set the current density based on the type of chrome plating:
  • Decorative chrome: 10–15 A/dm² (amperes per square decimeter)
  • Hard chrome: 30–60 A/dm²
• Use a rectifier with ripple control (low AC ripple) to maintain stable DC output.
• Monitor voltage (typically 3–12V), which varies with solution concentration and temperature.
• Adjust settings based on part size, geometry, and desired plating thickness.

Technical insight: Higher current density increases deposition rate but may cause burning or roughness if not controlled.

5. Initiating the Plating Process

Once all parameters are set, the electroplating reaction begins upon applying current.

• Turn on the power supply and allow current to flow through the circuit.
• Chromium ions (Cr⁶⁺) in the solution are reduced at the cathode (workpiece), forming a metallic chromium layer.
• Agitate the solution gently—via air sparging or mechanical movement—to ensure even ion distribution and prevent pitting.
• Monitor plating time closely; thickness builds at approximately 0.25–0.5 microns per minute depending on current density.
• Perform periodic inspections using a micrometer or coating thickness gauge for precision applications.

Tip: For complex shapes, use auxiliary anodes or shields to achieve uniform coverage.

6. Finishing and Post-Plating Treatment

Proper post-treatment ensures durability, appearance, and corrosion resistance of the plated surface.

• Turn off the power supply and carefully remove the workpiece from the bath.
• Rinse immediately with distilled or deionized water to neutralize and remove residual chromic acid.
• Dry the part thoroughly using hot air or a clean lint-free cloth.
• For decorative finishes, buff or polish with fine abrasives to enhance luster.
• Apply a clear protective coating (e.g., lacquer) if additional corrosion resistance is needed.
• Dispose of used plating solution and rinse water in compliance with environmental regulations.

Best practice: Conduct a water-break test after rinsing—beading indicates residual contamination.

Professional Recommendation: For consistent, high-quality results, maintain detailed process logs including bath composition, temperature, current density, and plating time. Regularly analyze the plating solution for contaminants (e.g., trivalent chromium buildup) and replenish as needed. Consider automated systems for high-volume operations to improve repeatability and safety.

Plating Type	Current Density (A/dm²)	Temperature Range (°C)	Typical Thickness (µm)	Primary Applications
Decorative Chrome	10–15	45–55	0.25–1.0	Automotive trim, fixtures, consumer products
Hard Chrome	30–60	50–65	10–100+	Hydraulic rods, industrial rollers, tooling
Thin Dense Chrome	20–40	55–65	1–10	Aerospace, high-wear components

Additional Considerations

• Bath Maintenance: Regularly filter the solution and monitor specific gravity to prevent contamination and ensure consistency.
• Environmental Compliance: Hexavalent chromium is hazardous. Use mist suppressants and closed-loop systems to minimize emissions.
• Quality Testing: Perform adhesion tests (e.g., bend or quench tests), microhardness measurements, and salt spray testing for corrosion resistance.
• Alternative Options: Consider trivalent chromium plating for reduced environmental impact and safer handling, though it may differ in color and hardness.
• Training: Ensure all operators are trained in chemical safety, emergency procedures, and proper waste disposal protocols.

What to Consider When Selling Chromium Plating Solution

Selling chromium plating solutions requires a strategic approach that balances product quality, regulatory compliance, environmental responsibility, and customer support. As demand for high-performance surface treatments grows across industries such as automotive, aerospace, and manufacturing, business owners must ensure their offerings meet both technical and safety standards. This guide outlines the key considerations for successfully marketing and selling chromium plating solutions while maintaining credibility, compliance, and customer satisfaction.

Important Note: Chromium plating solutions—especially those containing hexavalent chromium—are regulated due to their hazardous nature. Always ensure compliance with OSHA, EPA, and REACH regulations when handling, storing, transporting, and selling these chemicals.

Key Factors to Consider When Selling Chromium Plating Solutions

• Quality and Purity

  The performance of a chromium plating solution is directly tied to its chemical composition and purity. Customers expect consistent, high-quality results, which depend on using premium-grade chromium salts free from metallic impurities such as iron, nickel, or copper. These contaminants can lead to poor adhesion, uneven deposition, pitting, or dull finishes.

  To build trust and demonstrate reliability, offer comprehensive product documentation including batch-specific test reports, Certificate of Analysis (CoA), and conformance to ASTM or ISO standards. Sourcing from manufacturers that utilize advanced purification and quality control systems ensures your products deliver superior plating efficiency, brightness, and corrosion resistance.

• Product Variety and Applications

  Not all chromium plating applications are the same. Different industries require tailored solutions based on performance needs:

  • Hard Chrome Plating: Used in industrial and engineering applications for wear resistance, durability, and repair of worn parts (e.g., hydraulic rods, piston shafts).
  • Decorative Chrome Plating: Applied over nickel or copper layers for aesthetic appeal in automotive trim, plumbing fixtures, and consumer hardware.
  • Functional Trivalent Chrome: A safer alternative to hexavalent chrome, increasingly used in environmentally sensitive sectors.

  Maintaining a diverse product line enables you to serve a broader customer base—from heavy machinery manufacturers to boutique metal finishers. Consider offering custom formulations or technical consultation to help clients select the right solution for their specific process parameters.

• Packaging and Safety Compliance

  Chromium plating solutions, particularly those based on chromic acid, are classified as hazardous materials. Proper packaging is essential not only for safety but also for legal compliance during storage and transportation.

  Use chemically resistant containers made from HDPE or fluoropolymer-lined materials that prevent leakage and degradation. All packaging must be clearly labeled with:

  • Hazard symbols (e.g., GHS pictograms)
  • Product name and concentration
  • First aid measures and emergency response instructions
  • Manufacturer and supplier contact information

  Provide updated Safety Data Sheets (SDS) compliant with OSHA’s Hazard Communication Standard (HCS) and international frameworks like CLP/GHS. Ensure your logistics partners are certified to handle dangerous goods, especially for cross-border shipments.

• Customer Education and Technical Support

  Many buyers—especially small workshops or new entrants—may lack in-depth knowledge of electroplating chemistry and best practices. Offering robust technical support can differentiate your business and foster long-term loyalty.

  Consider providing:

  • Detailed application guides (e.g., bath preparation, current density, temperature control)
  • Video tutorials on safe handling and troubleshooting common plating defects
  • On-site or virtual training sessions for large clients
  • Access to a technical hotline or email support team

  Educational content such as blog posts, webinars, or downloadable checklists not only adds value but also positions your brand as an industry authority.

• Environmental Considerations

  With increasing regulatory pressure and corporate sustainability goals, eco-friendly alternatives are gaining traction in the plating industry. Traditional hexavalent chromium baths are highly toxic and generate hazardous waste, leading to strict disposal requirements and environmental risks.

  Offering trivalent chromium plating solutions—which are significantly less toxic and produce fewer harmful emissions—can align your business with green manufacturing trends. These solutions are now widely accepted in automotive, aerospace, and electronics sectors due to improved safety profiles and easier wastewater treatment.

  Additionally, partner with suppliers who follow sustainable manufacturing practices, such as closed-loop water systems, energy-efficient production, and recyclable packaging. Highlighting your commitment to environmental responsibility can enhance brand reputation and appeal to ESG-conscious clients.

Consideration	Key Actions	Benefits	Regulatory Alignment
Quality & Purity	Provide CoA, use high-purity salts, conduct batch testing	Consistent plating results, reduced defects	ASTM B650, ISO 4524
Product Variety	Stock hard chrome, decorative, and trivalent options	Broaden market reach, increase customer retention	Industry-specific standards
Packaging & Safety	Use chemical-resistant containers, GHS labeling, SDS provision	Compliance, reduced liability, safe handling	OSHA HCS, EPA, DOT, CLP
Customer Support	Offer guides, training, technical assistance	Improved customer satisfaction, reduced returns	Best practice adherence
Environmental Impact	Promote trivalent chrome, sustainable sourcing	Regulatory compliance, brand differentiation	REACH, RoHS, ELV Directive

Pro Tip: Regularly audit your supply chain and stay updated on evolving environmental regulations. Transitioning early to low-impact plating technologies can future-proof your business and open doors to contracts with environmentally responsible manufacturers.

Additional Recommendations for Success

• Develop strong relationships with reputable chemical manufacturers to ensure consistent supply and quality.
• Offer sample kits or trial sizes to help new customers evaluate your products before bulk purchasing.
• Invest in digital marketing to showcase your expertise—use case studies, testimonials, and educational content.
• Monitor customer feedback to identify areas for improvement in product performance or service delivery.
• Participate in industry trade shows or associations to stay connected with market trends and innovations.

Selling chromium plating solutions goes beyond simply moving inventory—it involves building trust through quality, safety, and knowledge. By focusing on purity, application diversity, compliance, education, and sustainability, you position your business as a reliable partner in the surface finishing industry. As environmental and regulatory standards continue to evolve, proactive adaptation will be key to long-term success and competitiveness.

Frequently Asked Questions About Chromium Plating

Q1: Is chromium plating hazardous to human health?

Yes, certain types of chromium plating can pose significant health risks, particularly those involving hexavalent chromium (Cr(VI)). The plating solution—often referred to as a selenium-containing or "Selming" solution—typically includes hexavalent chromium, which is classified as a known human carcinogen by agencies such as OSHA and the IARC.

• Inhalation Risk: When hexavalent chromium becomes aerosolized during electroplating processes, workers may inhale fine mists or fumes, increasing the risk of lung cancer and respiratory diseases.
• Skin and Eye Contact: Direct exposure can lead to dermatitis, skin ulcers, and eye irritation due to its corrosive nature.
• Long-Term Exposure: Chronic exposure has been linked to nasal septum perforation, asthma, and kidney or liver damage.

Due to these dangers, industrial facilities must implement strict ventilation systems, personal protective equipment (PPE), and regular air quality monitoring to protect workers.

Q2: What is the difference between hexavalent and trivalent chromium?

The key differences between hexavalent chromium (Cr(VI)) and trivalent chromium (Cr(III)) lie in their chemical structure, toxicity, and biological behavior:

Property	Hexavalent Chromium (Cr(VI))	Trivalent Chromium (Cr(III))
Chemical Charge	Negatively charged ions (e.g., CrO₄²⁻)	Positively charged ions (e.g., Cr³⁺)
Toxicity	Highly toxic and carcinogenic; regulated globally	Low toxicity; essential nutrient in trace amounts
Biological Penetration	Easily crosses cell membranes due to its charge	Poorly absorbed; binds to proteins and enzymes
Health Risks	Lung cancer, respiratory illness, skin burns	Minimal risk; no conclusive evidence of long-term harm
Industrial Use	Traditional chrome plating (being phased out)	Modern, eco-friendly plating alternatives

Due to safety and environmental concerns, many industries are transitioning from Cr(VI) to Cr(III)-based plating solutions, which offer comparable performance with significantly reduced health risks.

Q3: Is chromium plating waterproof?

Chromium plating is not fully waterproof but offers strong water resistance and excellent corrosion protection. It functions as a durable, thin metallic barrier that shields the underlying substrate from moisture and environmental degradation.

The plating process involves several critical steps:

1. Cleaning: The substrate is thoroughly cleaned to remove oils, oxides, and contaminants.
2. Electroplating: The part is immersed in a chromium electrolyte bath and subjected to an electric current, causing chromium ions to deposit uniformly on the surface.
3. Bonding: Chromium atoms form a metallurgical bond with the base metal, creating a smooth, hard, and reflective finish.

While the layer is typically only a few microns thick, it effectively slows down oxidation and water penetration. However, if the coating is scratched or porous, moisture can reach the substrate and initiate corrosion. For maximum protection, chromium plating is often applied over a nickel undercoat, especially in harsh environments.

Q4: Is nickel chrome plating better than stainless steel?

In terms of corrosion resistance and surface durability, nickel-chrome plating often outperforms many grades of stainless steel—especially in specific industrial and decorative applications.

• Corrosion Resistance: Nickel-chrome plating forms a highly inert, non-porous barrier that prevents moisture and oxygen from reaching the base metal. In contrast, some stainless steels (particularly lower grades) can develop surface rust or pitting when exposed to chlorides or acidic environments.
• Aesthetic Appeal: Chrome plating provides a bright, mirror-like finish that is difficult to achieve with stainless steel, making it ideal for automotive trim, fixtures, and consumer products.
• Cost-Effectiveness: Plating allows manufacturers to use less expensive base metals (like carbon steel or brass) while still achieving high performance and visual appeal.
• Durability: The hardness of chromium enhances wear resistance, reducing scratching and abrasion compared to bare stainless steel.

However, stainless steel remains superior in structural integrity and overall longevity in extreme conditions. The best choice depends on the application: use nickel-chrome plating for enhanced appearance and moderate environmental exposure, and stainless steel for heavy-duty, high-stress environments.

Q5: Is trivalent chromium toxic?

Trivalent chromium (Cr(III)) is significantly less toxic than hexavalent chromium and is considered safe for both industrial and environmental use.

Key points about trivalent chromium:

• Biological Role: Cr(III) is an essential micronutrient involved in glucose metabolism and insulin function. It is naturally present in foods like meat, whole grains, and certain vegetables.
• Low Bioavailability: Unlike Cr(VI), trivalent chromium does not easily penetrate cell membranes, reducing its potential for systemic toxicity.
• Skin and Respiratory Safety: It poses minimal risk of irritation or sensitization, making it safer for workers in plating facilities.
• Environmental Impact: Cr(III) compounds are less soluble and more stable in the environment, reducing leaching and contamination risks.
• Regulatory Status: Not classified as a carcinogen; widely accepted in eco-friendly plating technologies.

While excessive intake of Cr(III) supplements may cause mild side effects, occupational exposure during plating operations is generally not associated with serious health effects. As a result, trivalent chromium is increasingly replacing hexavalent chromium in modern surface finishing industries.