It is a question we get asked time and again: ‘What is the best finish for my steel project?’
Ensuring the correct finish to a steel project is just as important as the fabrication process. When deciding the best finish, you will need to consider if the finish is being applied for purely aesthetic reasons, or for additional corrosion protection. If the correct finish is not applied there is a good chance the product won’t stand the test of time and you will quickly start to notice signs of deterioration!
A high-quality finish will provide the ‘wow’ factor, and if your product is being used as a showcase feature, such as a staircase which has been designed to impress, there are a multitude of aesthetic finishing options to choose from.
As experts in all things steel (and a responsible company who want our customers to be nothing less than delighted!) we can offer the best advice on how to achieve a desired look and feel, whilst also ensuring the product is well protected from the elements.
In this blog we will take you through some of the common metal finishing products and practices that can be used to give a high-quality finish and help your product last a lifetime…
Preparation is key: Shot blasting
First things first, preparation! In order to achieve a good finish, it is necessary to remove all mill finish and scale, common on large sections of steel. Removing imperfections will enable a good base (sometimes called ‘etch’) for the paint or coating to adhere to.
Shot blasting is the process of using abrasive particles applied under high pressure to remove impurities. A rapidly turning throwing wheel housed in special steel structure which guides the metal, is used to blast abrasive particles onto metal profiles. Shot blasting is also used to remove rust and old paint.
Powder Coating: A high-quality, consistent finish
Powder coating is a dry finishing process that has become very popular in recent decades. Powder coating can be used on a wide range of products and provides a high-quality, consistent finish. It can be applied to large areas in little time, making it an efficient option for large scale projects. Powder coating is used for both its functional and durable qualities, and also for its decorative and attractive finish, which is available in a wide range of colour options.
Now for the science part… powder coatings are based on polymer resin systems, combined with curatives, pigments and other additives. These ingredients are melt mixed and once cooled, they are ground into a uniform powder. A process called electrostatic spray deposition (ESD) is generally used to apply the powder coating, involving a spray gun which provides an electrostatic charge to the powder particles to attract them to the metal. After application, the parts are cured in an oven and the coating chemically reacts to produce long molecular chains which are very resistant to breakdown.
Still with us? The result of this process is a highly durable, consistent coating which will protect metal in outdoor environments exposed to the elements. Due to the method of application, powder coating is a cost-effective way to treat aluminium, mild steel and stainless steel. You will commonly see powder coating finishes on items such as handrails, fence panels and gates.
Galvanising: Stand the test of time!
Galvanising is an Industrial finish applied to mild steel or carbon steel to provide a protective coating. Applied using a hot dipping process, a layer of zinc is used to coat the metal and prevent rusting and corrosion. Galvanising is an extremely versatile process and an easy means of providing corrosion protection for construction materials exposed to atmospheric conditions. Galvanising can be applied to large sections of metal but is also cost effective for use on smaller items, making it a highly versatile option. Once galvanised, the steel will require no further maintenance and will stand the test of time!
‘Warm to Touch’: Additional comfort and luxury
Similar to the powder coating process, ‘Warm to Touch’ is a plastic coating, applied using a spray system and used on items such as handrails to provide additional comfort. The high-quality PVC coating prevents heat conductivity away from the hand. Available in various colours, the material is UV stable and weather resistant, making it ideal for external or internal requirements and industrial or commercial environments. The finished result is extremely hard wearing and provides a flush, consistent finish with no snags. With many combinations of colours and textures available, this range of products allows designers to find the finish to suit their individual development.
Stainless steel is an alloy of Iron with a minimum of 10.5% Chromium. Chromium produces a thin layer of oxide on the surface of the steel known as the ‘passive layer’, which prevents corrosion of the surface. An increased amount of Chromium gives an increased resistance to corrosion.
There are many different types of surface finish on stainless steel, some of which are applied later during processing. Finishes include polished, brushed, blasted, etched and coloured finishes. Selecting the right surface finish is important in determining the corrosion resistance of the stainless steel surface. A rough surface finish can lower the corrosion resistance. Check out the various recommended finishes from the British Stainless Steel Association here.
Stainless steel can provide an impressive ‘wow’ factor and can be used to complement various architectural features. It is also incredibly hard wearing and requires no additional maintenance after installation.
Wet Paint (Epoxy Coating)
Wet paint systems, also referred to as 2 Pack Paint or Epoxy Paint, are paint systems involving an acrylic paint melamine (the colour) and a hardener resin. When combined, these two resins result in a chemical reaction which produces a hardened solution.
Epoxy paint systems are a top choice for many industrial coating applications, including steel, metal and concrete. The system is applied using a spray, making it better suited and more efficient for larger, less intricate applications.
Epoxy coatings provide optimum protection against abrasion, corrosive fluids and extreme temperatures and are also resistant to many corrosive substances. Once epoxy cures, it becomes a hard, finished surface which will last many years, even in exposed conditions.
Zinc plating is the process of electrodepositing Zinc onto mild steel or iron parts. Zinc plating acts as a sacrificial coating and will slowly corrodes over time, protecting the steel underneath. The other main benefit of zinc plating is that the coating itself improves the look of the base metal, clear zinc plating has an attractive bright silver/blue appearance.
To get the best results for zinc plating, the condition of the material is very important. Clean rust/scale free metal allows for the best finish.
For better corrosion resistance the zinc layer is passivated, there are different types of passivation available depending on the application and depending on if the product will be exposed to the elements. Clear (blue) passivate is commonly used for machine parts and washers, screws, fasteners, and the finished look is a bright shiny silver/blue. Yellow passivate offers better corrosion resistance and so is often used for motor parts and general parts to be used outdoors. Black Passivate (Trivalent Chromium) offers excellent corrosion resistance and is mainly used for decorative purposes where a dark finish is required.
Zinc plating is well suited for smaller, intricate applications which may have moving parts, such as hinges or door locks.
For more information about which finish is right for your project, get in touch with our team!
Call 0151 637 3600 or email firstname.lastname@example.org.