Zintec Steel - Powder Coated Planters

To reduce the risk of rusting when used outdoors, mild steels are typically ‘galvanised’ – which means they have a protective layer of zinc applied to their surfaces. ‘Zintec’ steel is a category of galvanised steel where the zinc layer has been electroplated to the mild steel, in a fine, uniform layer. Relative to other galvanising technologies – such as hot dipped galvanisation – Zintec steel can be made into extremely precise forms, and its surface finish is much fairer and more perfect. 

However, for outdoor use, Zintec steel must be painted: both to further protect the material against corrosion, and for aesthetic reasons. 

Low cost.

Zintec steel is very efficient to work with, using modern sheet metal fabrication technologies; and it can deliver complex and precise design execution, and a very high level of finish, at a low cost. 

Commercially-acceptable longevity. 

“You get what you pay for”. And Zintec steel’s lower cost is reflected in technical performance and longevity which are lower than some other metals – such as stainless steel. 

However, some projects will be in relatively protected locations, where damage to the Zintec steel is unlikely. And not all projects demand extreme longevity – sometimes 5-10 years is perfectly acceptable. And cost is very often an overriding consideration. So, on many landscape projects, Zintec steel’s reduced longevity is considered a ‘commercially-acceptable compromise’ when set against Zintec’s substantial cost benefit.

And, finally, if well cared for, there is no reason why a Zintec steel landscape product should not last for decades. However, the products would need to have the protective paint finish reapplied periodically [typically every 9-12 years]; and always after any significant damage that cuts through to bare metal.

Relatively inexpensive upscaling options.

Where costs are under pressure, but ‘regular’ powder coated Zintec steel really isn’t quite good enough, then there are relatively inexpensive options to upscale the technical performance of the Zintec steel option.

Technical performance might need to be improved to increase longevity, and/or to enhance the landscape product’s resistance to damage. The solution is to use the remarkable flexibility of PPC, and to specify a high-quality paint finish to meet these enhanced requirements. In simple terms:

“It is a lot cheaper to paint a Zintec Steel landscape product with a Rolls-Royce paint finish, than it is to paint a 316-grade Stainless Steel product with a Mondeo paint finish”. 

However, in unprotected environments – such as public realm and streetscapes – we would always recommend powder coating onto 1.4003-grade stainless steel, rather than Zintec steel – for reasons discussed in this article within our Specifiers Area: 1.4003-grade Stainless Steel - The Unique Advantages. 

For landscape products, powder coated Zintec steel has a ‘natural home’ in outdoor spaces which are either relatively protected, and where they are valued sufficiently to be looked after. And there are a wide range of situations where powder coated Zintec steel can deliver all of its initial cost and aesthetic benefits – and still last for decades.  

Workplace and Residential Roof Terraces

With the price of inner-city land at an ever-increasing premium, both companies and private individuals have “looked up” to find outdoor space that they can utilise. The motivation might be:

• For companies: to reward valued staff with additional workplace amenities, and to engage with clients in a more meaningful environment.

   
• For private individuals: to increase their enjoyment of their property, and to increase its potential future value, by unlocking the potential value of previously ‘void’ spaces. 

In these protected, and cared-for, environments, then powder coated Zintec steel is absolutely the right choice – there is simply no point in spending more.

Relevant Project examples:


Tapestry – Frith Street, London W1

Roof Terrace – Westminster, London SW1

Private Residential Gardens

The same logic applies to private residential gardens at ground level. Unless it is a super-prime residential project, there is little-to-no justification for spending more. 

However, in super-prime projects, it may be warranted to upscale technical performance by using a premium PPC finish – for example as here: Hampstead ‘Super-Prime’ Residential Development.

And in certain locations, such as coastal, the additional cost of stainless steel is warranted – for example as here: Salcombe Beachfront Residence. And in coastal locations there are also other specification considerations, as discussed in this article: Specifying Metal Planters for Coastal Locations.


Other Relatively Protected Environments

Other relatively protected environments are legion, and include schools, universities and clubs, healthcare environments, offices, and many hotel, restaurant and hospitality venues. 

Manufacturing Quality

Corten steel and stainless steel “don’t want to rust” – but Zintec steel does. So the longevity of a Zintec steel landscape product will be critically determined by the quality of its manufacture.  

When barrier coatings, such as PPC, are used to retard corrosion, great care must be taken to ensure complete coverage, without gaps, cracks, or pinhole defects. Small defects can act as an Achilles' heel, allowing corrosion to penetrate the interior and causing extensive damage even while the outer protective layer remains apparently intact for a period of time. And these gaps, cracks etc. are most often inherent to the design - for example:

• Open-seamed planters should not be made from Zintec steel, as complete barrier coverage simply cannot be guaranteed, and all seams must be specified as ‘closed and fully welded’.  
   
• All holes [for irrigation, drainage, lighting etc.] must be designed-in, and laser-cut into the planters prior to barrier coating. Cutting on-site penetrations into the finished planters, or other landscape products, will destroy the barrier coat; and on-site remedial coatings will never be as good as the original.

Barrier coating must be to all surfaces – external, internal, underneath. And, ideally, the planters will be designed such that all elements are independently coated before final assembly. At IOTA, all internal stiffeners, cross-braces and planter bases are individually PPC painted, and inspected for complete coverage, prior to careful, manual final assembly.

Finally, even if a barrier coating, of the highest quality, is expertly applied to a landscape product which has been perfectly designed – even then, much of the benefit may still be lost, if the planter wasn’t well made in the first place. Specific manufacturing quality points to note include:

• All cut metal areas must be carefully de-burred, and faired off smooth, prior to barrier coating.

   
• All welds must be complete, finished and faired – again to ensure perfect barrier coating.

   
• All seams must be closed, to avoid crevice corrosion.

And all of the above must be checked, throughout the production process, by rigorous Quality Control Procedures.