The most common finishes and coatings include: uncoated or plain, black oxide, nickel, phosphate, stainless steel, zinc, cadmium, and chrome. Plating is a process in which a mixed metal solution is deposited in a ranging thickness to the surface of a substrate or base material. Plating offers a range of purposes, depending on the specific plating material and process applied. Plating can increase corrosion and wear resistance, improve electrical conductivity, strengthen and harden, and coat the material with an attractive shiny smooth finish. Understanding the basics of each finish is very important before deciding the right specification. So, what is the perfect coating? And what are the benefits and differences between them? At BW Industrial Sales we are here to help. With combined industry knowledge of over 100 years, we are not just a fastener supplier but a trusted source for quality products and valuable knowledge on all things fastener related. Using our helpful tips and guide , we hope to provide you with the information needed to further your fastener knowhow and improve your selection decision in the future.
Finding the right finish and plating can be a confusing task. That’s why we break down the process and benefits of each coating process to help give you a better understanding of the fastener coating you need. There are many variations of coatings in a large range of materials, each used for specific benefits desired to increase a plain fastener's performance and look.
The structural integrity, build longevity, and overall effectiveness of any task will be positively or negatively affected by the fastener coating choices made. Depending on the desired use, harsh environments, waters, chemicals and other factors can damage or render structurally unsound many types of alloys and materials. Coatings like plating’s and finishes help increase the longevity, strength, and resistance to many of the common elements faced by fasteners. But which one is best for your specific task?
Although not technically a coating, Stainless steel acts in a similar preventative way as many coatings. With over 150 grade types and finish variations, stainless steel is a great option for any corrosion or chemical prevention along with many high strength, high temperature tasks. Due to its formability and effectiveness, stainless steel fasteners are highly popular and used in industries including; marine, chemical, textiles, food, medical, outdoor and much more. The 304 and 316 grade stainless steel is the most commonly used stainless. The 304 Stainless is more commercial grade and 316 stainless is more marine grade in effectiveness. For more information on stainless steel fasteners please click the link to see our downloadable PDF.
Overall, Stainless steel is a perfect option for any machine, tool, or application that operates in corrosive or harsh environment.
Hard Chrome is one of the most well-suited methods to protect against wear and tear. With this expensive plating technique, a thin layer of chromium is electroplated (electrically charged) to the metal. Hard chrome plating provides aesthetics along with corrosion resistance, ease of cleaning, and an increased surface hardness, making it a great combatant to wear and tear. There are different types of chrome plating designed for a multitude of different tasks like; hydraulic cylinders and automotive /mechanical components, molds, dies, press punches, tooling, industrial equipment and components, and much more. With a large range of uses and applications, chromes’ low temperature required to apply and ability to form to any shape, makes it a great choice.
Typically applied to increase durability, hardness and visual appeal, chrome plating is a good option for any industrial and decorative application.
Similar to chrome plating, Nickel plating involves electroplating a thin layer of nickel to the desired metal. This thin plating can help with corrosion resistance, wear-resistance and be aesthetically decorative. It can also be used for salvaging purposes, applying a thick coat to increase fit of undersized fasteners. There are many different types of Nickel plating, including; Watts nickel plating, this process creates a bright finish typically used for decorative and corrosion resistant purposes. Nickel sulfamate, used for engineering applications due to its high efficiency and corrosion resistant coating. All-chloride, Sulfate-chloride and all-sulfate, which have similar characteristics and run at low voltages with higher stressors. Good for plating the inside of pipes and fittings. Another plating solution is hard nickel, which has a high tensile strength, and Black nickel, which typically is plated on brass, bronze or steel, has a non-reflective surface great for visual military and decorative purposes.
Like chrome, Nickel plating can increase durability and visual appeal, making it a good option for mostly decorative applications.
Zinc is one of the most cost effective and commonly used fastener coatings. It has a high corrosion resistance making it a popular coating for all kinds of metal fasteners including; screws, bolts, anchors, washers, nuts, studs, rivets, rods and hardware. Zinc has a wide variety of application processes that enable it to be utilized for many different uses. Some of these processes include the most popular methods zinc plating, hot dipped galvanized (HDG), flake coating, and mechanical plating creating a very smooth and shiny layer, coating and protecting the metal within from harsh environmental factors that would otherwise cause damage or corrosion. Zinc fasteners are also frequently post-treated with a chromate conversion coating. This coating typically affects the color and use/life expectancy of the fastener, appearing in clear, blue, yellow or black. There are different coating mixtures that promote these finishes and they are typically named accordingly:
Using the method of electroplating, the clear white-blue toned zinc is typically applied to brass, bronze, copper, aluminum alloy, iron, steel, and other common alloys. This application can be referred to as zinc plating or galvanization. During this process, the zinc oxidizes forming a thin, tightly adherent and protective layer known as Zinc Oxide. This coating is good for small fasteners, generally for use in interior or low intensity external environments.
This is the process by which the fasteners are tumbled in a drum with glass beads, water, chemicals and zinc powder. The collision creates a cold welding of the zinc powder onto the parts and gives them an even coating.
Formed by coating iron and steel fasteners with molten zinc and spinning until the excess zinc is removed. This zinc bath is typically 450 degrees Celsius and has over 4 preparation stages including a degreasing, pickling, flux solution, rinsing in between each bath and drying before the fastener is ready for galvanizing.
This process is the method of coating typically small components with two layers of a mix containing zinc and aluminum flakes. Once the base and top coat are set, this coating will act as a great corrosion resistant solution, using the top coat as a preventative or delayer of interior damage from external factors.
Phosphate coated fasteners are created using a crystalline conversion coating formed on metal base fasteners. The coating on its own does not provide any corrosion resistance, instead it requires another step. Typically, phosphate coatings serve as surface preparation for further coatings like oils, sealers, or paints to achieve a more effective corrosion resistance. Phosphate coatings form a black to gray hue, and are usually used on steel fasteners but are also compatible with a variety of materials like aluminum.
Cadmium is a soft white metal which is electroplated onto steel. Acting as a “sacrificial coating”, cadmium is designed to corrode before the substrate material, extending the use life of the fastener. It provides excellent corrosion resistance, good lubricity, solderability, and has good paint-based characteristics. Unfortunately, due to its toxicity and sacrificial characteristics, cadmium is not environmentally friendly and may be banned for use on many applications. Typically used in electrical, aerospace, mining, marine, automotive and military industries, cadmium coated fasteners are highly versatile.
Gold plated fasteners include nuts, screws, bolts, bolts, washers and much more. They are primarily used for high vacuum cleanliness and anti-galling applications. With a wide range of operating temperatures, gold is an exceptional conductor with great corrosion resistance, visual appeal and lubricity. Most gold fasteners will be found in the electronics industry.
While all finishes come with ranging benefits, knowing the perfect one for you is a highly important decision. Learn more about the finishes and plating’s we offer with our PDF info graphic "Finishes & Plating’s".
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