The Benefits of Polyester Powder Coating [PPC]

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The Benefits of Polyester Powder Coating [PPC]


An explanation of why Polyester Powder Coating [PPC] is overwhelmingly the most popular specification for paint finishing in the landscape industry, including for planters and street furniture.

Definition:

Powder coating is a type of coating that is applied as a free-flowing, dry powder [unlike conventional liquid paint which is delivered via an evaporating solvent]; and the powder coating is typically applied electrostatically and then cured under heat”.
 

A. THE BASICS: WHY APPLY AN EXTERNAL FINISH AT ALL…?

Not all sheet metal items will have an external finish applied. For example:

  • Stainless Steel and Corten Steel are often left unfinished, as they will not degrade, and they have a distinct and attractive aesthetic in their ‘raw’ form.
     
  • The premium decorative metals [Lead, Zinc, Copper, Brass/Bronze] are often pre-patinated, and then left to develop their own natural, characteristic patinas over time. These metals are too beautiful [and too expensive…!] to cover up.

However other sheet metals will most often need to have an external finish applied, particularly in the outdoor environment. The three principal reasons for this requirement are:

  1. Cheaper, more reactive metals – most notably Mild Steel – need to be externally finished to protect against corrosion.

  2. Mild Steel, Aluminium, Stainless Steel or Corten Steel may also be externally finished for decorative purposes.
     
  3. And finally, any metal may have an external finish applied to deliver a desired functional property [an example of this would be applying an anti-graffiti coating].

There is a plethora of external metal finishing systems available, including electroplating, galvanising, anodizing, and paint finishing – along with many, highly specialised, coating systems for specific industries and applications. Each finishing system will deliver its own solution to a particular combination of design and specification requirements. 

Within the landscape industry, and industry in general, overwhelmingly the most popular and prevalent choice is paint finishing – which may be either wet painting, or Polyester Powder Coating [PPC].

Of these two generic paint finishing systems, PPC is by some margin the most commonly specified option. So what are some of the key benefits of PPC…?
 

B. THE KEY BENEFITS OF PPC
 

B.1. PPC offers enormous aesthetic choice

There is a prejudice, amongst some specifiers, that PPC is functional, utilitarian, and dull. In fact, nothing could be further from the truth.

What is true, however, is that PPC is not good for super-funky art finishes, and/or faux finishes [like, say, finishes replicating naturally-patinated Copper].  High-end wet paint systems can offer this – but at a cost of somewhere between £200-400 per sq metre [or somewhere around 8-10 times the price of high-quality PPC]. In the real world, these kind of price premiums for specialist wet paint finishes are almost never justifiable for exterior, landscape products. In Plain English: what a client might be prepared to pay for a hotel reception desk, they will not pay for the planter outside the door…!

With the above caveat only, PPC offers enormous aesthetic choice, and creative licence to a specifier.

In addition to the standard RAL, BS, or Pantone colour series, there are myriad proprietary ranges available from specialist, high-quality paint manufacturers – such as Interpon/AkzoNobel, ISG, Tiger Drylac and Syntha Pulvin. These ranges include, inter alia:

  • ‘Anodic’ ranges, which replicate the distinctive look of Anodized Aluminium.
  • Bespoke, multi-tonal ranges which replicate the warmth and energy of Bronze, in all of its many shades.
  • Metallic ranges which can achieve a depth of finish and metallic ‘bling’ indistinguishable from much more expensive, wet paint, liquid coatings.
  • Bespoke, fashion-driven ranges, developed seasonally in association with trend and innovation consultants.

And the above is truly just the tip of the iceberg.

As the essential PPC application technology is common, new powder coat formulations tend to go from the development bench to market swiftly [without the ‘black arts’ of some wet paint innovations]. Thus new PPC ranges are being brought to-market all the time, further expanding the aesthetic choice. 

 

B.2. PPC is very cost-effective

PPC is a very cost-effective paint finishing system; and it is often a half, or a third, of the cost of equivalent wet paint systems.

There are a number of reasons why PPC is so cost-effective – and these include:

  • PPC is fast. A fabricated item can typically be through PPC paint finishing, packed, and dispatched – all in the same day. Thus a PPC paint facility can push through a much greater volume of product, quicker, than a corresponding wet paint facility; and a PPC facility can thus occupy correspondingly less space, with a lower capital expenditure overhead.
     
  • PPC is accurate, and forgiving. Where complex shapes need coating, the powder coating process ensures complete coverage even on shapes with hidden surfaces, curves, angles. And, when cured in the oven, the powder coat particles melt, flow and cross-link to create a skin with a uniform finish, without ‘runs’. Compared to wet painting, PPC gets the right result first time, more often – without the cost of rectifying imperfections.
     
  • There is minimal waste with PPC. Unused or over-sprayed polyester powder can simply be recovered and reused, economically, easily and above all safely.
     
  • PPC facilities have a low cost of compliance. No solvents are used, there are virtually zero Volatile Organic Compounds in powder coating, and the essential processes are clean. PPC has been able to keep up with changing environmental pollution regulations in recent years, with minimal additional compliance costs.

The efficiency of PPC, and its corresponding cost advantage, is a core reason for its use in the landscape industry – where budgets are typically constrained. 


B.3. PPC is a highly flexible technology, and it can be tailored precisely to the requirements of the brief

Perhaps the most common misconception about PPC, amongst specifiers, is that PPC is a ‘thing’ – like timber or steel or trees [or whatever…]

In fact, ‘PPC’ is merely a generic description of a paint application process, which has a great many variables, which need to be defined in a precise specification – such as:

  • The preparation regime for the metal prior to PPC application
  • The number of PPC coats applied
  • The exact specification and composition of the different coats

All of these variables impact on technical performance; and PPC is thus a highly flexible technology, which can be tailored precisely to the requirements of the brief.

And the good news, again [vs. wet painting] is that adding extra functional requirements to a PPC specification tends not to break the budget. Indicatively, the cost difference between a 'Rolls Royce' vs. 'Mondeo' specification in PPC might be 20% or so – whereas in wet painting it could quite easily double the cost.

IOTA is always happy to advise on what would be suitable PPC systems for a particular brief. However the specifier should at least give prior consideration to what are the requirements of the brief, on issues such as:

  • The client’s expectation on Design Life Performance – specifically longevity.
  • The environment in which the landscape product is to be located.
  • The risk of abuse and/or physical damage to the product.
  • Whether there will be a maintenance programme in place to rectify any such damage.
  • Whether there are any additional, highly specific concerns in the brief – such as graffiti.

The above are the kind of considerations which would go into decisions on what would be suitable PPC systems for a given brief.

 

C. SOME COMMON PPC SPECIFICATIONS

Finally, below are three common specifications routinely used by IOTA. They are listed in order of increasing technical performance; and are ‘badged’ with common car names, to make the point that there is an inevitable link between cost and technical performance and cost.

The PPC products given are from the Interpon ranges by Akzo Nobel, simply because these products are what IOTA uses most. However IOTA also routinely uses equivalent coatings from other PPC manufacturers [such as IGP and Syntha Pulvin], which can readily be substituted within a specification.

 

C.1. Mondeo Option

This is the PPC system that IOTA is using on a daily basis. This option meets the minimum quality standard to which IOTA is prepared to put its name; and it is fit-for-purpose for the vast majority of residential and light commercial schemes.

The system comprises:

Material: Zintec [Zinc-Plated] Steel
Pre-treatment: Degrease and Abrade
2-Coat application:

  1. Primer: Cromadex 903 Etch Primer
  2. Topcoat: Interpon D1036

Please note: IOTA uses most often Zintec [Zinc-Plated] Steel, on which basis a first coat of Etch Primer is acceptable. If Mild Steel were used, then a Zinc Primer would have to be substituted.

 

C.2. Jaguar Option

A lot of IOTA’s work is in public realm, where a more robust surface is required.

A formulation which IOTA uses a lot for public realm, and highly recommends, is the Interpon D1036 Textura range which has a finely textured, highly-durable finish. Textura is described by Interpon as: “A hard-wearing , scratch and knock-resistant powder coating, perfect for high-traffic areas. The durable finish disguises imperfections and offers a low maintenance, easy-cleaning solution for public areas.”

The exact system used with this option will vary, as public realm schemes often come with additional requirements and complexities that need to be taken into consideration.

 

C.3. Rolls Royce Option

Finally, there are some extreme environments, where a ‘Rolls-Royce’ PPC system is cost-justified.

This subject is more fully discussed in two further articles on the Specifiers Area of IOTA’s website – namely:

A Coastal environment is self-evidently ‘extreme’; whereas what is ‘extreme’ in Super-Prime Residential Developments is the level of client expectations in terms of quality, longevity etc. In both cases, we recommend the same PPC system.

The essential specification requirement is to state that:

The PPC coating and application system used must ensure extreme longevity in C3/C4 environments – defined as:

  • C3  Urban and industrial atmospheres with moderate sulphur dioxide pollution
  • C4  Industrial areas and coastal areas with moderate salinity

Two such systems commonly used by IOTA in these circumstances follow a 3-coat system with coating products from Akzo Nobel, which might be used as example specs. – these comprise: 

Option A
Material: Mild Steel
Pre-treatment: Blast Cleaned SA 2.5
3-Coat application:

  1. Zinc Primer: Interpon PZ 790
  2. Intermediate/Primer: Interpon BPP 330
  3. Topcoat: Interpon D1036

Option B
Material: Zintec [Zinc-Plated] Steel
Pre-treatment: Degrease and Abrade
3-Coat application:

  1. Primer: Cromadex 903 Etch Primer
  2. Intermediate/Primer: Interpon BPP 600
  3. Topcoat: Interpon D1036

There are indeed PPC systems that are ‘above Rolls Royce’ in terms of cost and technical performance, which IOTA has the skills, experience and resources to apply. [For example: IOTA has a contract to manufacture some elements for the Hinckley Point C nuclear power station, the PPC specification for which is extraordinarily complex]. However, for 90% of the requirements of the UK Landscape Industry, the Rolls Royce spec given above is as good as it needs to be.

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