#076 / 2006

How green is my mdf?

The demise of eco-friendly Woodstalk™ last December has producers pondering alternatives. Dow's product contained no-added formaldehyde, used surplus wheat straw fibre, machined easily and was manufactured in Canada. For furniture manufacturing the equivalent replacement panel is an eco-friendly, medium-density fibre board (MDF) - plywoods are expensive and have edge-sealing issues, as do particle boards. (See furniturelink's Buy Green for sources of non-MDF eco-panels.)

Made with a no-added formaldehyde adhesive, Medite II from SierraPine in Oregon is the established environment-friendly MDF panel on the market. Recently three alternative eco panels have been released - Patinna F4S, Arreis and Platinum. Each have positive and negative features (the table below lists properties and other data for all four panels). furniturelink undertook to evaluate them and presents the results in three categories - adhesives, certification/recycling and physical properties.

Adhesives (binders)

The three adhesive resins used in the manufacture of MDF (in order of common usage) are urea formaldehyde (UF), methylene dipenyl diisocyanate (MDI) and phenol formaldehyde (PF).

Urea formaldehyde - Panels are moderately water resistant [1]. Controversy concerns their continous emission of small quantities of formaldehyde gas over the lifespan of the product, a gas that has been classed a probable carcinogen by the US Environmental Protection Agency (EPA). Because of this health threat and the green-house factor, the MDF panel industry worldwide has been actively reducing fomaldehyde emissions. In North America, industry sources have claimed the emission rates for "standard" UF MDF have been reduced from about 1.5 ppm in the early 1980s to the current target level of 0.3 ppm (or less) [2].


Comparing panels at Ornamentum Furniture, Vancouver.

The Patinna F4S panel's formaldehyde emissions at 0.05 ppm are 83 percent lower than the 0.3 ppm industry standard. It also meets the stringent Japanese building standards, which allows it to be used with no restrictions. The 0.05 ppm level will also meet the proposed year 2012 California Air Resources Board (ARB) formaldehyde emission standards for composite wood products.

Methylene dipenyl diisocyanate - Panels are very resistant to water and damp atmospheres [1] and contain "no-added" formaldehyde. Very low "background" levels may be emitted.

Often wood contains small quantities of formaldehyde naturally. As such, panels with test levels of 0.05 ppm or less can be considered to be at or close to natural "background" levels. To put this in perspective, the formaldehyde emission level certificate [8] for Medite II and Arreis (that both use MDI adhesives) states "Lab tested to less than 0.05 ppm (of formaldehyde)" - not that the emissions are zero. [9]

Phenol formaldehyde - Panels are very resistant to water and damp atmospheres [1] and may have very low "background" levels of formaldehyde emission. Although formaldehyde is present in the PF resin molecule, it is far less prone to hydrolysis (break down) than the formaldehyde in the UF resin molecule. Platinum, the only panel of the four made with PF resin, is a new development for the manufacturer, so its listed properties are still to be reviewed [4].

Certification and recycling

Most MDF (including "standard" grades) is made from recycled wood waste produced by mills and manufacturing plants. SierraPine adds that it uses recycled "pre-consumer" fibre sourced from forests with Sustainable Forestry Initiative (SFI) certification for its Arreis and Medite II panels. SFI certification is not recognized by the LEED (Leadership in Energy and Environmental Design) green building rating system. LEED recognizes the Forest Stewardship Council (FSC) certification awarded to the Patinna F4S and Platinum panels.

The Meridian Institute provides a balanced analysis of the SFI and FSC certification systems.

Physical Properties and Other Data of 3/4" MDF Panels [3]
PropertyUnitPatinna F4SMedite IIArreisPlatinum [4]
Internal bondlb/in²85130115116
Modulus of rupturelb/in²6,5005,0005,2006,500
Modulus of elasticityb/in²508,000500,000520,000507,600
Modulus of hardnesslbs (janka)n/avail.1,1501,150n/avail.
Moisture content% (oven dry)8.03.0 - 6.04.0 - 6.06.5
Thickness tolerancein+/- 0.005+/- 0.005+/- 0.005n/avail.
Adhesive [5]UFMDIModified MDIPF
Formaldehyde ppm [2]0.05 [7] [7] 0.05
Fibre content certification100% FSC100% SFI100% SFI100% FSC
Country of origin New ZealandUSAUSANew Zealand
Cost [6]85%100%85%105%

Physical properties

The above chart shows that the four panels are almost equal in density and modulus of elasticity (stiffness). Patinna F4S and Platinum have higher modulus of rupture values. Patinna F4S has the lowest internal bond strength (lowering the formaldehyde levels can result in lower bond strength), which may involve some design constraints.

Grant Wyllychuk, owner of FSC chain-of-custody certified Ornamentum Furniture in Vancouver, BC, ran some simple machining "tests" on small samples of Patinna F4S, Arreis and Medite II (see above). Tests included bandsaw and tablesaw cuts, routered dados and biscuit slots. Although there were minor variations in performance, Wyllychuk found no substantive difference in the three panels' machinability.


While waiting for new agriboard panels to become available, furniture designers and makers can use the MDF panels listed here or substitute a different format of wood-based panel from the furniturelink list of buy green.

With the increasing numbers of architects interested in LEED certified products and the new composite panel emission regulations proposed by California, more "green" panels will likely be developed. As new panels enter the market, accompanied by green marketing "spin," designers and makers must gather all the facts needed for "due diligence." To determine which panel to use for a particular application, furniturelink recommends obtaining a Material Data Safety Sheet (MSDS) issued by the manufacturer and a properties specifcation sheet that includes the results of an independent ASTM E-1333 (large chamber) formaldehyde emission test. With this information, designers and makers will be better prepared to an make informed decisions to benefit all, including the environment.

[1] Source
[2] Based on ASTM Test E-1333 (large chamber)
[3] Data from specification sheets of manufacturers; see also [4]
[4] Data for Platinum based on early estimates and do not guarantee actual results
[5] UF = Urea formaldehyde, MDI = Methylene dipenyl diisocyanate, PF = Phenol formaldehyde
[6] An estimate of panel price comparison, where Medite II equates to 100 percent
[7] SCS certificate states, "Lab tested to less than 0.05 ppm" (see [8] below)
[8] Update (2013) the SierePine Arries and Medite II MSDS now states "manufactured with no added formaldehyde"
[9] In 2013 minor edits were made to the paragraph for clarity

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