Zinc - Patinated Planters

IOTA’s zinc planters are clad in architectural-grade zinc sheet, which is 99.995% pure zinc alloyed with trace amounts of copper [to increase hardness] and titanium [to improve creep resistance and thermal stability].

The inner Zintec steel planters are fully-welded and faired, and powder coat protected to the highest standards. Although these planters will not be seen, their structural integrity is central to the longevity of the final zinc-clad planters.

The architectural-grade zinc sheet is then bonded to the inner Zintec steel planters using industrial contact adhesives. These adhesives not only create an extremely robust and long-lasting bond, but their flexibility is also necessary to mitigate the differential thermal expansion rates of the two metals.

All of the edges and corners of the zinc sheet are then TIG Brazed and faired, to create a perfectly seamless structure; before the finished planters are expertly patinated by hand.

The key benefits of true zinc sheet are:

• Corrosion Resistance. Zinc is highly resistant to corrosion. When exposed to moisture and air, it naturally develops a protective, matte-grey carbonate layer called a patina, which continuously self-heals minor scratches.
   
• Extreme longevity. Genuine architectural-grade zinc sheets are known to last decades to over a century when properly cared for. Although zinc will ‘self-heal’ if damaged, extensive, long term physical abuse will decrease its longevity.
   
• A characteristically beautiful aesthetic. IOTA’s zinc planters are supplied with a pre-patinated finish; with the intention being that the planters will then age naturally outdoors. The images here show pre-patinated zinc planters at a relatively early stage of natural ageing; with a general background patina resembling old lead, with natural and characteristic zinc oxide highlights starting to come through. Over time, the planters will become generally lighter, with increasing levels of tonal variation and highlights.
   
• Essentially zero maintenance. Any maintenance that is deemed necessary would be for purely aesthetic – rather than functional and/or structural – considerations. If the zinc is seriously scratched up, although it will self-heal this might still look unsightly; but the zinc can be sanded back to bare metal, and then re-patinated. 

Zinc is expensive so it is only ever specified for high-end schemes.

High-End Commercial Office Rooftops

Zinc has exceptional corrosion resistance and longevity, and is aesthetically very pleasing; so, where budgets allow, it can be a sound long-term investment for high-end commercial office rooftops, especially those that also serve as entertainment and meeting spaces for clients. 

For further guidance on specifying planters for rooftops please review this article: Roof Terrace Planter Design Guide.

High-End Protected Public Spaces

Generally-speaking, zinc would never be specified for unprotected public realm – the cost would be prohibitive, and the surface can be damaged too easily.

However zinc is perfectly suited for protected public spaces, such as museum gardens, hotel outdoor reception spaces,  and locked communal garden squares.

High-End Managed Residential Schemes

These build-to-rent schemes have some unusual financial priorities, which tend to favour a long-term investment view and a desire to minimise ongoing maintenance costs. Where budgets allow, zinc’s combination of benefits can justify its cost in this sector, and its singular beauty can also mark out a scheme as being of the highest quality.

For further guidance on specifying planters for this sector please review this article: Specifying Planters for Build-to-Rent, Student Living and Managed Residential Developments.

Heat Conductivity

Zinc is highly heat-conductive, transferring heat more than twice as fast as carbon steel and nearly eight times faster than stainless steel.

As IOTA’s zinc planters are made from cladding zinc sheet onto steel, this does mitigate this negative to a great extent. However it would still be wise to specify that the planters should be insulated internally, which IOTA typically does with 25mm Celotex or equivalent SIP panels.

Soil Chemistry & Liners

While zinc is mostly inert, trace chemicals, acidic soils, and fertilizers can react with the zinc, potentially causing degradation or stripping the protective layer. This is another benefit of IOTA’s construction methodology, as only the steel inner planter comes into contact with the growing medium.

Environmental & Coastal Exposure

In highly corrosive, industrial, or coastal environments with moderate to high salinity, unprotected zinc can degrade.

Zinc can also look very different in a coastal location, and much less distinctive and beautiful. In a standard environment, zinc develops a medium, slate-grey patina. Near the coast, airborne salt chlorides integrate into the weathering layer, changing the chemistry of the patina. This results in a much lighter, chalkier, almost white-grey matte finish.