There are two common grades of stainless steel and using the wrong grade in the wrong location can have disastrous effects to the finish, so here is the right way to specify this.
- Internal balustrades are protected from weather conditions and therefore 304 grade stainless steel is best suited.
- Externally avoid 304 grade and make sure you use 316 marine grade stainless steel. 304 grade has potential to discolour. This discolouration often appears to be rust, and is perceived as unsightly; it will require regular maintenance. Regal always recommends 316 grade externally.
- To swimming pools and coastal areas make sure you use 316 marine grade stainless steel, you may also choose to use a bright mirror polished finish in lieu of a brushed finish which gives a higher resistance to corrosion. Another process often used is electropolishing. By applying a direct current of electricity to the item to be Electropolished whilst immersed in an electrolyte solution, metal is subsequently removed, leaving a smoothed surface that optimises the corrosion resistance of the steel in any given environment.
- Physical Vapor Deposition (PVD) – Physical Vapor Deposition coating, defines a variety of vacuum coating methods. These coating techniques are used to apply an extremely thin film to objects that require protective barriers, decorative colours, or various other functional benefits. Once applied, the coating is nearly impossible to remove, and won’t wear off on its own.
Some people prefer to use 304 grade externally to keep prices low. This substandard practise leads to poor product performance and aesthetics. To ensure longevity, balustrades should always be made in 316 grade. This applies to the tube, all components and even the welding wire.
This is probably one of the most cost effective materials to make a balustrade in, but it has it’s pitfalls. Mild steel is typically finished with a powder coated or basic paint finish. Galvanised finishes are used to provide some level of corrosion resistance.
Even if you are using a galvanised finish externally there is risk of corrosion. Hot dip galvanising is carried out by dipping the balustrade into a molten zinc tank. The balustrade is then lifted out and the excess coating is allowed to drip off. These droplets form surface imperfections which are sometimes sharp. Sharp edges are normally linished, however without good skill and care the galvanised coating can be taken off completely so you are back to an unprotected mild steel core. This can allow rust to kick in very fast which downgrades the building appearance and can impair the structural integrity of the balustrade.
Mild steel finishing options
- Polyester Powder Coated (PPC) – Powder coating is a type of coating that is applied as a free-flowing, dry powder. The main difference between a conventional liquid paint and a powder coating is that the powder coating does not require a solvent to keep the binder and filler parts in a liquid suspension form. This is a process that is done by an off site specialist. PPC processing has advanced over resent years, and can provide some realistic wood, metallic, and brushed effects.
- Epoxy Paint – Epoxy coatings are often used in coating mild steel constructed stairs and entry level balustrades, and can be sprayed finished when the product is in situ. It is generally packaged in two parts that are mixed prior to application. The two parts consist of, an epoxy resin which is cross-linked with, and a co-reactant or hardener. Epoxy coatings are formulated based upon the performance requirements for the end product. When properly catalyzed and applied, epoxies produce a hard, chemical and solvent resistant finish. They are typically used on concrete and steel to give resistance to water, alkali and acids.
Laminated glass is recommended where higher levels of safety or security are required. The lamination and interlayer does not affect the transparency of the glass, but the interlayer can incorporate a wide range of tints, colours, patterns and textures if required. Regal Balustrades Ltd recommends the use of a capping with large units of laminated glass as panels can occasionally be mis-aligned leaving unsightly edges. Mis-aligned panels may still be within the lenient regulatory requirements relating to this. The common types of interlayers are;
- PVB (Poly Vinyl Butyral) is the most common type and is suitable for most applications. This is the solution normally recommended by Regal.
- EVA (Ethylene Vinyl Acetate) is an external quality interlayer.
- SGP (SentryGlas Plus, a registered trade mark of DuPont) could be specified for exposed or potentially ‘dangerous’ environments; an SGP interlayer may be up to 5 times stronger than a PVB interlayer.
- CIP (Cast In Place) is not a laminated interlayer sheet, but rather is a poured resin. Regal does not recommend the use of CIP panels because of the messy edge finish which requires concealing with edge strips.
Low iron glass – Extra clear glass is created by reducing the amount of iron within its content which removes the green tint inherent in standard glass. Extra clear glass’s almost completely transparent appearance means it has limited sun reflection properties. It’s widely used in windows or facades as it offers brilliant clarity, which allows occupants to appreciate true colours and to enjoy true-to-life views.
Acid etched is glass that has been chemically treated with an acidic material, such as hydrofluoric acid, to produce a surface finish that will diffuse transmitted light, reduce glare and has a “frosted” appearance. The treatment on the glass is used to diffuse light, reduce glare and obtain a translucent appearance. The treatment can be applied to provide different levels of translucence, either uniformly over the entire surface or in selected areas creating decorative patterns.
Heat Soaked Glass – With heat-strengthened glass the process involves placing the tempered glass inside a chamber and raising the temperature to approximately 290ºC to accelerate nickel sulphide expansion the cooling process is slower, which results in lower compression strength. Heat-strengthened glass is approximately twice as strong as annealed, or untreated glass.
As determined by BS 6399 and BS 6180: 1999 8.2, glass in freestanding barriers needs to be either toughened, or laminated and toughened, both conforming to BS 6206. All Regal’s glazed products use toughened glass panels which have been through a special heating and cooling process, creating high compressive surface stresses that render the glass to be stronger than ordinary annealed float glass.