« back to Materials section


Roofing is part of many interwoven systems within the building, providing waterproofing, rainwater collection, solar reflectivity and aesthetics.

Roof systems protect the house structure and interior from water penetration, wind and weather. In extreme weather situations, the roofing material also protects against wind-borne projectiles. Most roofing systems perform these tasks equally well, but each differs in life span, cost, and level of thermal protection.

(back to Materials)

Choices for Bull Street

The north roof on Bull Street is also a deck with outdoor seating and a wicking bed garden. The roof of the Pop Up supports a Solar PV System. Rain water collected from the roof beneath the deck is stored for garden irrigation, whereas rain water collected from the Pop Up and south roof are collected for re use within the building.

Material choice for roof: BlueScope Lysaght Longline 305 in zincalume as it has a long life span (material warranty is 15years in Castlemaine), excellent waterproofing at a low pitch, safe rainwater collection, solar reflectivity and aesthetics. Polyvinal Chloride (PVC) is on the LBC Red List and as such cannot be included in the project. All our rain water collection pipes will also be zincalume.

Atlantis Flo-Tank underground rain water collection system.

PEX pipe for all water distribution.

  • Black Multi-purpose water pipe
  • Blue – Cold water
  • Red Hot Water
  • Lilac Recycled water
  • Green Rain water

Details of Research

Galvanised, Zincalume or Colorbond?

Galvanised steel rusts and is therefore not as sustainable as Zincalume, since it has a shorter life span.

However, Fielders are an Australian Company, they manufacture their own old fashioned, double thickness galv roofing iron with the old fashioned deeper corrugations, providing a viable galvanised alternative. Manufactured in Camblefield, nr. Melbourne (120km from Castlemaine) 9-13 Jessica Road, Campbellfield, VIC 3061 (03) 9300 7700.

Colourbond is actually just a Zincalume base with a baked enamel coating in your choice of colour and therefore embodies more energy and resources.

Zincalume is the best product in terms of water collection quality, longevity, and has a high reuse/recycle value.

Some councils will only allow zincalume if it is replacing an original tin roof, but want colorbond for new roofs.

What type of roof is best for collecting rainwater for drinking?

A study conducted by The Cockrell School of Engineering, led by civil, architectural and environmental engineering Assistant Professor Mary Jo Kirisits, showed that, of the five roofing materials tested, metal (specifically Galvalume®), concrete tile and cool roofs produce the highest harvested rainwater quality for indoor domestic use. The study also showed that rainwater from asphalt fiberglass shingle roofs and increasingly popular “green” roofs contain high levels of dissolved organic carbon (DOC). Although other potential pollutants can be significantly lower on green roofs (turbidity and aluminum), the high DOCs are significant where these roofs would be used for potable rainwater collection.

Water with DOC is not necessarily dangerous on its own, but Kirisits says that when it’s mixed with chlorine – a common product used to disinfect water – the two substances react to form byproducts that potentially cause cancer and other negative human health effects.

Can BlueScope Steel recommend a product to be used in the collection of drinking water?

Recently BlueScope Steel commissioned the Australian Water Quality Centre to determine if their products meet the requirements of Australian Standard AS/NZ 4020 – 1999 “Products for use in contact with drinking water”.
The results of testing to the above standard have allowed BlueScope Steel to confidently recommend the use of COLORBOND® steel and ZINCALUME® steel for the collection of drinking water.
(BlueScope Steel only recommends AQUAPLATE® steel for the storage of drinking water)

Zincalume and colorbond are not compatible with copper. 

Rain water collection tanks 

Rainwater that is captured and stored correctly is a safe, economical and sustainable source of quality water. Rainwater is as safe as any source of water, provided certain safety precautions are taken as part of water capture, storage and distribution. In fact some say that rainwater is safer than water supplied through mains or reticulated water systems (ref: Dr Peter Coombes of the University of Newcastle in Australia). Australian mains water is typically stored in dams, treated with chemicals such as chlorine to kill of bacteria and make it safe, and then pumped through a network of pipes throughout the community.

Stan Abbott is the Director of the Roof Water Research Centre and a Senior Lecturer in Microbiology & Communicable Diseases at Massey University in Wellington, New Zealand. Stan’s research highlights the importance of incorporating good design features into rainwater harvesting systems.

  • Incorporating Gutter Mesh Systems – to help ensure gutters do not become blocked with leaves and debris; to prevent mosquito breeding habitats
  • Fitting Rain Heads at gutter downpipes – to separate leaves and debris from the flow of water; to keep mosquitoes out of pipe systems to the tank (especially in “wet” systems)
  • Preventing the First Flush of rainwater from entering the tank – to reduce the amount of roof pollutants
  • Insect proofing all tank openings (inlets and overflow outlets) – to prevent mosquitoes breeding
  • Regular Tank Maintenance of the tank, catchment system, roof and gutters, inlets to ensure a safe supply of water. Desludging may be required every 2-3 years, and whilst regular disinfection should not be necessary, can be undertaken if preferred.
  • Disinfect the supply if contamination is apparent.
  • Test the water periodically. 


Good Design Features Should Include:

  • A clean, impervious roof made from non-toxic material
  • The absence of lead flashings or lead-based paints
  • A covered and light-proof tank
  • A course filter and first flush device
  • Wire mesh screens to cover all tank inlets
  • Tank taps or draw-off pipes that are at least 100mm above the tank floor (alternatively, a floating arm draw-off valve)
  • A tank floor which slopes towards the sump and washout pipe
  • A well covered manhole for easy access and inspection

Available to Download: enhealth – Guidance on use of rainwater tanks (2004)

Bull street Rainwater harvesting tank

On Bull Street we are collecting the rain water from all four units into one large underground tank. The reason for this is that by combining the storage we minimise the site impact in regard to space but also in minimising the amount of excavation & materials needed. The centralised plumbing layout reduces the quantities of material used in tank, pipes & fittings which is a resource and financial saving.

Concrete or Plastic?

Both concrete and polypropylene are compatible with zinalume. Concrete has a higher embodied energy so we have chosen to use Atlantis Flo-Tank modules which are made from recycled polypropylene. The liner is also made from polypropylene (not recycled).

Polyvinyl Chloride (PVC) is on the LBC Red List and as such cannot be included in the project. 

The information on PVC is startling and worrying especially as most houses have it in many components, most prevalently in those that carry our water. (ref: Plastic PVC Poisoning all living Things – YouTube 23.10.13, published on Dec 29, 2012) The production of PVC is significantly more harmful to the environment than any other plastic, and not only because they are not recyclable. The process of making PVC plastics involves the fusing of chloride molecules — derived from petroleum — with heavy toxic metals like lead and cadmium. These toxins stabilise and plasticise PVC, but because of their use and the chemical properties of chlorine, byproducts of PVC production tend to be significantly more toxic and persistent in the ecosystem, traveling up the food chain to people. As the Centre for Health, Environment, and Justice notes, PVC plastic is unique in its risks to health and environment. No other plastic contains as harmful substances, or as hazardous byproducts, as PVC plastic.

  • These toxins are building up in water, air and the food chain.
  • The results: severe health problems, including cancer, immune system damage, and hormone disruption.
  • No one can escape contamination.
  • Everyone, everywhere has measurable levels of chlorinated toxins in their bodies.

The PVC industry has been plagued by workers health and safety issues for decades. Many industries are aware of what PVC is doing to people but they are doing nothing to stop the use and production of PVC. When PVC is burned it gives off toxic hydrogen chloride gas, which turns into hydrochloric acid on contact with moisture within our lungs. PVC alternatives are available and are safer for the environment and us.http://www.acereport.org/pvc2.html http://chej.org/

CHEJ (The Center for Health, Environment and Justice) coordinates a national campaign working to phase out PVC, the most dangerous plastic to our health and environment. In the past two years, they have successfully moved major Fortune 500 companies away from this unnecessary toxic plastic and towards safer and healthier alternatives.

Dow Chemical running from responsibility for poisoning around the world, including Plaquemine Parish, Louisiana: http://bhopal.net/petition/applicatio

And then there are the chemicals added to PVC: Phthalates, a family of industrial chemicals used to soften PVC plastic and as solvents in cosmetics and other consumer products, can damage the liver, kidneys, lungs and reproductive system — particularly the developing testes — according to animal studies.

Medical devices made of flexible PVC, such as IV bags and tubing, can leach the phthalate DEHP into patients, resulting in some of the highest exposures to this toxic chemical.

Beauty Secrets: The Dangers Of Phthalates: Industry Spin vs. Fact: http://www.ewg.org/node/8174 & http://www.healthychild.org/issues/me

Deborah Cadbury, The Assault on the Male, BBC Horizon film:http://www.youtube.com/watch?v=LkxIJJ… & http://www.americanhealthstudies.org/

“The Gender Benders: Are environmental ‘hormones’ emasculating wildlife?,” first in a two part series, Janet Raloff, Science News, January 8, 1994, pg. 24 http://www.sciencenews.org/pages/sn_e… http://findarticles.com/p/articles/mi

Foreword to The Feminization of Nature: Our Future at Risk by Deborah Cadbury (London: Hamish Hamilton [Penguin], 1997) ISBN 0-14-026205-9 http://www.dhushara.com/book/renewal/

Multiple grassroots organizations of consumers have spoken out about the hazards of PVC plastic. These organizations include the Center for Health, Environment, and Justice, the Grassroots Recycling Network, Greenpeace, and even include a feature film on the dangers of PVC plastic, Blue Vinyl. Each organization has a compendium of resources and information about PVC plastic, and events and actions organized to halt the use of PVC plastic in everyday consumer items.

Opposition continues to grow to the use of this incredibly harmful material in our everyday lives. http://www.noharm.org/us_canada/issue… 75% of PVC is used in the building industry. (ref: Healthy Building Science healthybuildingscience.com 23.10.13)

Some commons places where you should look in identify possible PVC exist:

  • Carpet backings
  • Flooring
  • Window Shading
  • Water Piping
  • Electrical Wiring
  • Roofing membranes
  • Window Assemblies

So what are our alternatives to PVC?

info@living-future.org.au, Suzette Jackson

Copper (REF:Advantages and Disadvantages of Copper Pipe Plumbing D Swain 23.10.13)

When choosing the type of plumbing you want in your home, some of your options will include steel, plastic, and copper. Copper pipe plumbing has numerous advantages and disadvantages when compared to other materials. This article will discuss some of the advantages and disadvantages of copper pipe plumbing.


One of the first advantages of copper pipe plumbing deals with installation. Copper is a relatively soft metal, so it can bend rather easily. Therefore, copper pipe plumbing can be installed using less fasteners and connectors. Since there will be less hardware used, it will be easier to install this type of plumbing.

Another advantage of copper pipe plumbing deals with the water supply. Bacteria can grow in other types of plumbing, especially plastic designs. Copper pipe plumbing is bacteriostatic. This means that bacteria can’t grow in the copper pipes. Also, there is no risk of lead poisoning as lead isn’t used during the manufacturing process.

Copper pipe plumbing is also extremely durable. Unlike designs made of steel, copper pipes will resist corrosion. They are also capable of withstanding ultraviolet rays unlike plastic designs. These characteristics make copper pipe plumbing ideal for outside uses such as in a sprinkler system.

One of the final advantages of copper pipe plumbing is that it resists temperatures changes well. If a fire ever occurs in your home, toxic gases will be released if you have CPVC, or plastic pipes. Copper pipe plumbing doesn’t burn, so it won’t release toxic gases.


One of the most important disadvantages of copper pipe plumbing is the expense involved. Copper is a considerably more expensive material than plastic. Although the installation of copper pipe plumbing requires less hardware, it will still be more expensive to install.

Another disadvantage of copper pipe plumbing deals with water acidity. This type of plumbing is only suitable for water that has a pH between 6.5 and 8.5. Water that comes from a well may be too acidic for copper pipe plumbing. Therefore, it’s best to use this type of plumbing in locations that are supplied by the city water supply.

The following are two very informative answers on Green Building Advisor.com sourced on 23.10.13

PEX vs Copper

‘We are building a net zero energy home and need to decide to use PEX or Copper. What is the healthy option.. will PEX leach from the plastic.. and Copper leach lead from the joints? Would love to hear both the pros and cons for each application. Thank you,’ – Karen


2 Answers

PEX will not leach bad chemicals into your plastic nor will copper leach lead from the solder, which is now lead free. PEX will be more durable than copper long term as it is more resistant to corrosion and freeze-thaw action. Coppers vulnerability to corrosion will actually help reduce the corrosive effect of your water and will help prevent the water from corroding your faucets long term, (and faucets are still allowed to have lead in them, which is why it’s still a good idea to rinse the dust out of the tumbler with the first bit of water out of the faucet) It’s easier to replace corroded faucets than pipes and a corroded faucet may drip, but it won’t cause long term water damage the way a corroded pin hole in a copper pipe will. So, all things being equal you will be better off with PEX in the long run.

However the next question you will want to ask is “how do you design the piping system?” Gary Klein is the leading philosopher on this issue and the first of a four part series he has written is available to download here: http://savegas.com/NewsArticles/HotWaterDist_Part1.pdf to get part 2 just substitute a 2 for the one in the URL and 3 and 4 likewise.

The short answer is that water flows much differently in a pipe than most people think, it eddies at elbows and tees and the hot water doesn’t just push the cold water ahead of itself as it rushes down towards the sink but it swirls and mixes with the existing cold water in the pipe and comes out lukewarm at the faucet long before it gets hot and that all these issues are exacerbated by low flow fixtures.

So pipe lay-out and design is much more important than many (and the code) were aware. We want to remove every elbow we can from the hot water piping system, most especially elbows that are close to the water heater (do you have an elbow at the top of your tank? most likely.) We also want to get rid of “bull-headed tees” and only use tees that are the same diameter in the straight direction and smaller diameter in the side direction. Of course we want to use shorter pipe runs and insulate hot water pipes, never put them under a slab, and we should be questioning the diameter of every pipe.

If you need hot water in a primary bath for two sinks, a tub and a shower it is fair to ask how often more than one of these fixtures will be used at the same time and if they are all low flow except for the bathtub you may want to serve them with a half inch line or at least supply the tub with a dedicated half inch home run from the water heater and supply the rest of the fixtures with a dedicated half inch line. Think about it, plan it out, question assumptions but most especially don’t let the plumber “just do it to code” or you’ll be watching cold water run out of the hot water tap for a long time before you hop in that shower.

Gary has evolved greatly in the time since these articles were written and has gotten involved in the development of the Metlund D’mand recirculating hot water system (good) and Navien’s demand water heater (not a fan). I warn people about the flow rate related pressure drop problem with the Navien water heaters which is an issue for those of us who build luxury green homes and is why many of us have chosen to stick with the Rinnai and Quietside condensing demand water heaters.

But mostly I think we’ve stepped past one of the most elegant solutions which is to have a central solar/ demand water heater solution with small under counter or closet located electric hot water tanks in the remote bath rooms that just receive hot water from the central water heater and keep it from cooling down for no wait usage in that bathroom. It’s an in-expensive and effective solution. So long as you are able to provide the 1,500 watts those units draw from time to time to keep the water from cooling down.

Interesting anecdote about that though, I built a house a while back that was very spread out and the client called a year or so after moving in to say that the water heater wasn’t getting hot water to the primary bath for some reason. I stopped by to check it out and discovered that the 110 volt water heater had been wired to a 220 breaker and had most likely burned up the element the first time it was used but, because it was constantly being refreshed with hot water so long as people were living there, it never got cold until they went on vacation and they lived there for a year without knowing the auxiliary water heater was broken and had fast hot water all that time. I fixed it, but my point is that it probably doesn’t use much electricity if it works well when the breaker is popped.


Posted Wed, 02/17/2010 – 20:43

2.As with most building materials today, it’s not easy to determine the relative merits of copper and PEX for domestic water supply. There are significant benefits and liabilities, including deleterious health impacts of both. The following is a summary of the issues. My best advice at this point is to use copper for chlorinated water supplies and PEX for private wells, particularly with acidic water, or with ionic water softeners.

Copper is a naturally-occurring mineral with associated mining impacts, but it’s easily recyclable (and often contains a high recycled content), while cross-linked polyethylene is not.

Copper domestic water piping must be soldered with “lead-free” solder (no more than 0.2% lead) and fittings, except in CA and VT under new rules can contain up to 8% lead. Soldering flux is also toxic as well as corrosive to the copper. For this reason and because of galvanic and chemical reactions, copper is vulnerable to corrosion and pin-hole leaks. It is highly vulnerable to frost-breakage. Over time, copper pipes build up a layer of mineral deposits from hard water which constricts water flow and, along with internal burrs and irregularities, creates turbulence and noise. Water turbulence in pipes, often exacerbated by too-small diameter piping, causes increased dissolution of heavy metals such as lead and copper, particularly when water pH is less than 6.5 (acidic, as most water is today). Noise and water-hammer is exacerbated by rigid tubing, angular direction changes and high velocities due to narrow pipe.

Not only is dissolved lead a problem in domestic water systems, though largely mitigated since the lead ban in 1998, but dissolved copper has become increasingly recognized as a threat to both human health and the environment, limited by the EPA to 1.3 parts per million in domestic water supplies.

Copper dissolution occurs in new piping, and in piping carrying acidic water, soft water (low dissolved solids), or water with high dissolved oxygen. It is recommended that water sitting in copper supply pipes for more than 6 hours be flushed for 30 to 60 seconds before using for drinking or cooking, that hot water (more dissolved metal) never be used for drinking, cooking or (especially) baby formula.

Cross-linked polyethylene (PEX) piping, on the other hand, is flexible, smoother, does not scale or corrode, is resistant to acids, and is relatively resistant to frost-breakage. Because it comes in long spools, it has far fewer fittings (usually just one at each end) to leak or cause turbulence, and requires no solder or torch fuels. Because it is far simpler to install, it can typically be done less expensively, even with the now-common “home run” system in which each hot and cold fixture gets supplied by a separate pipe, allowing the use of smaller-diameter tubing, eliminating the pressure-drop common in most homes and allowing a centrally-located “switch panel” to isolate each fixture.

PEX has been used in Europe since the 60’s and in the US since the 80’s. It’s made from a petrochemical plastic and, while it has 46% more embodied energy per pound than copper, because it is so much less dense (lighter) it has 85% less embodied energy per unit volume.

Copper smelting and production also creates environmental emissions which cause both human toxicity and environmental impacts. PEX has recently been approved, after an extensive Environmental Impact Study, by the plastic-phobic state of California for all water supply systems, concluding that it would be “an environmentally superior action with respect to public health and hazards, water quality and air quality.” It is accepted by all North American plumbing codes. However, see the lawsuit below to overturn the California approval.

Copper ingestion is now associated with flu-like symptoms, kidney damage, Wilson’s disease, learning deficiencies in adolescents, and Alzheimer’s disease. It is not known whether it is carcinogenic.

Coalition of Environmental, Consumer, Public Health and Labor Organizations Have Filed Lawsuit to Overturn the Schwarzenegger Administration’s Approval of PEX Pipe

On February 19, 2009, a coalition including: (1) the Consumer Federation of California; (2) Planning and Conservation League; (3) Center for Environmental Health; (4) Sierra Club California; (5) California Professional Firefighters; and (6) the California State Pipe Trades Council jointly filed a lawsuit to overturn the Commission’s approval of PEX on the grounds that it was based upon a legally inadequate environmental impact report (EIR).

Potential Environmental, Health and Economic Risks Posed by PEX

Contamination of drinking water

The PEX EIR found that methyl tertiary-butyl ether (MTBE) and tert-Butyl alcohol can leach from PEX in amounts that exceed taste, odor and health guidelines set by the State of California for drinking water. The PEX EIR found that PEX pipes can initially leach as much as 290 ppb of MTBE. The California Department of Public Health and the California Office of Health Hazard Assessment have established a drinking water taste and odor standard of 5 ppb for MTBE and a drinking water public health goal and maximum contaminant level of 13 ppb.

The PEX EIR also found that PEX can leach ethyl tertiary butyl ether (ETBE), a chemical in the same family as MTBE, in amounts exceeding 100 ppb. An expert toxicologist report commissioned as part of the PEX EIR found that the leaching of ETBE from PEX pipe could contribute to taste and odor impacts, and could potentially lead to adverse health effects.

The PEX EIR found that PEX pipe is susceptible to permeation by outside contaminants such as pesticides, oil, gasoline, benzene and termiticides.

Numerous studies and articles submitted to the State of California comparing potable water pipe materials, including variants of PEX, polybutylene, polypropylene, CPVC, copper and steel, have found that PEX displayed the strongest biofilm formation and the strongest initial promotion of the growth of Legionella bacteria.

California’s January 2009 approval of PEX relies upon the less-protective PEX chlorine resistance standard ASTM F2023, instead of the much superior NSF P171 standard. ASTM F2023 only assures an adjusted lifetime of 25 years, while the NSF P171 standard assures a 40 year adjusted lifetime. At least one reputable PEX manufacturer (Lubrizol Advanced Materials, Inc.) has questioned the adequacy of this standard since it only results in “an expected service life of 25 years, five years less than the traditional home loan.”

Even short term exposure to sunlight can dramatically reduce the resistance of PEX to chlorine and result in premature rupture of the pipe. Studies show just a one-week exposure to sunlight may reduce the chlorine resistance lifetime of some PEX pipes by half; with a two week exposure completely depleting PEX of any chlorine resistance.

Lack of Recyclability

Because it is a thermoset plastic, PEX cannot be melted down and reused. A 2005 report by the San Francisco Department of the Environment found that PEX was the only type of plastic piping that no plastic recycler would accept. Copper pipe generally contains around 70% recycled material and has almost a 100% recycling rate.

Toxic Smoke

PEX produces toxic smoke when burned in building fires.

Testing and Certification

PEX-c is cross-linked in a cold process using electron beams rather than the heat and chemical based process for PEX-a or PEX-b, and is the cleanest of the three. PEX tubing meeting the health effects requirements of NSF/ANSI Standard 61 will bear either the NSF-61 mark or the NSF pw (potable water) mark on the print string. The NSF pw Mark indicates the product meets health requirements as well as performance, long term strength and quality control requirements.

Water exposed to PEX tubing and associated fitting systems are tested for the following contaminants as required by NSF/ANSI Standard 61:

  • VOCs (Volatile Organic Compounds)
  • Semi-volatile compounds
  • Phenolics
  • Regulated Metals including antimony, arsenic, barium, beryllium, cadmium, chromium, copper, lead, mercury, selenium, and thallium
  • Methanol
  • Tertiary butyl alcohol
  •  MTBE (methyl tertiary butyl ether)
  •  Any other potential contaminant identified during the formulation review.

These test methods are capable of detecting contaminants in water as low as 4 parts per billion.


Posted Wed, 02/17/2010 – 22:25

Note: there are mentions in blogs about plant based alternatives for plastics, HDPE from Brazillian sugarcane, and plant based plastics and polimers from hemp, Honesty, Castor and Meadowfern.

Polyethylene Pipe and Fittings (ref: http://www.iplex.com.au/)

Material Properties: Terms frequently used to describe this material when used for engineering applications are high density (HDPE), medium density (MDPE) and most recently high performance (HPPE) polyethylene. Others PE types, such as low density (LDPE) and linear low density (LLDPE) are sometimes used for irrigation pipelines.

The Type 50 PE of AS1159 that was in common use until 1994, is an HDPE with a long-term design stress of 5.0 MPa. AS/NZS4130 and AS/NZS allow for three specific classifications by material strengths and sub classifications by performance at elevated temperatures.

The higher strength PE 80B and PE100 compounds are sometimes referred to as second and third generation materials. They were introduced into general service in the late seventies and early nineties respectively.

POLIplex polyethylene is an integrated family of PE pipes produced by Iplex , based on PE 80B, PE 80C and PE100 materials. PE80B material has 50-year design strength of 8 MPa whilst PE100 material’s minimum required strength is 10 MPa. Iplex POLIplex pipes are manufactured to AS/NZS 4130 from polyethylene’s complying with AS/NZS 4131.

PE Material Type               PE80B    PE100

MRS (50 year)     8 MPa    10 MPa

Flexural Yield Strength  27MPa  32 MPa

Circumferential Flexural Modulus (3 minute)     700 MPa                950 MPa

Circumferential Flexural Creep Modulus (50 year)           200 MPa                260 MPa

Density                  943 kg/m3            955 kg/m3

Tensile Yield Stress (50mm/min)               20 MPa                   25 MPa

Tensile Yield Strain (50mm/min)                8%           10%

Tensile Modulus                650 MPa                900 MPa

Poisson’s Ratio                   0.4           0.4

Thermal Expansion Coefficient 0.2 mm/m K        0.18 mm/m K

Thermal Conductivity    0.38 W/m K         0.38 W/m K

Material Composition

The polyethylene compounds used in POLIplex pipes and fittings are pre-compounded resins, either black or coloured with pigment, complying with AS/NZS 4131.

The following additives, if used, are added to the PE polymer base resin during the compounding process by the raw material manufacturer.

Anti-oxidants are used to inhibit oxidation of the polymer at the compounding stage and during subsequent processing. The oxidation induction test is an indicator of the efficacy of this additive and the residual amount after processing.

Carbon black is used in all black POLIplex pipe at a concentration of 2.25 ± 0.25% by mass as an ultra violet radiation absorber.

In natural and coloured PE materials, chemical ultra violet absorbers are used in lieu of carbon black.