Should Moisture Resistant MDF be Green?

Today there are numerous types of MDF on the market, each available in different grades with enhanced characteristics such as moisture resistance or fire retardance. At Skirtings R Us, we only manufacture our skirting board using high density, moisture resistant (MR) grade MDF, which we have sourced specifically for moulding and painting applications.

Traditionally, moisture resistant MDF has been associated with a green colour, but today there is large demand for MDF that retains the moisture resistant property, but is untinted - brown in colour - like normal MDF. This has caused concern in some forums, and among those who are more familiar with working with a green MR product than a brown.

If you have bought any untinted Moisture Resistant MDF we want to reassure you that the colour is not an indication of the materials properties.

This is a longer article. Jump to the relevant parts from here:

'How we know OUR MDF is moisture resistant if its not green?' click here.

'What makes MR MDF moisture resistant?'/Requirements of MR MDF' click here.

'WHY MDF is now manufactured in green and brown colours' click here.

Should Moisture Resistant MDF be green?

No. There is no mention of a green colour being a requirment of moisture resistant MDF in EN622-5: 2009. The bond strength and swelling rate required after testing by the standard above is attained with the addition of special resins and additives. The green colour is attained with the addition of a tint, which on its own cannot achieve the standards set out above. As such green tinting is not listed as a classification or testing factor in establishing moisture resistance in any British/European standard. For more info see 'What is moisture resistant MDF?' below.

How do we know our MDF is moisture resistant if it’s not green?

All the MDF we purchase is accompanied by a CE marking (conformité européenne - European Conformity) indicating the product and manufacturers compliance to all stipulations within and referenced by European Standards. You may recognise the logo below that signifies this.

EN 13986 governs and defines wood based panel for building applications (EN 13986 Wood-based panels for use in construction. Characteristics, evaluation of conformity and marking). This document is broad and defines MDF, chipboard, plywood, OSB etc as panel products for construction in general terms. EN-13986 refers to a series of EN product standards for specific product types also known as technical classes.

EN622 is the technical class for fibreboard products. Section 5 specifically standardises MDF and sets the standard for moisture resistance (EN622-5: 2009).

All MDF purchases we make are accompanied with a manufacturers technical specification sheet which references standard EN622-5: 2009.

What is Moisture Resistant MDF?

MDF is a sheet material made of wood fibres mixed with resin. When compressed under heat this mix produces an MDF panel. Moisture resistant MDF has a higher internal bond strength and slower swelling rate which makes it more durable in humid conditions than a standard MDF.

Here’s the technical bit involving regs if you're interested…

According to British/European standard BS EN622-5:2009 ‘Moisture Resistant’ MDF is classified when the swelling rate and internal bond strength of a panel meet or surpass the standard required in the table below. It also dictates the test and measurement procedures required for proving moisture resistance; EN317, EN319, EN321. These tests stipulate that bond strength and swelling rate is measured after cyclic exposure to either; a) submersion, freezing, and forced drying or; b) boiling.

A full version of these documents can be downloaded from: www.en-standard.eu

Here is a shot of the criteria requirements for Moisture Resistant MDF: 

Why have manufacturers moved away from tinting MDF?

Many industries like the furniture and skirting board industries apply a finish to their MDF, often a paint or veneer, which is scrutinised by customers. Often these finishes are applied in a thin layer which, if applied to a strongly coloured substrate like green, can cause the colour to grin through the veneer or paint.

Consumer demand for a quality product has therefore led MDF manufacturers to stock moisture resistant products in the ordinary brown colour, rather than green in some sizes.

Why are some MDF panels green and others brown?

Stocking both tinted and untinted variants of each panel size would place too much stress on MDF production and warehousing facilities, especially considering the product is essentially the same. Therefore, manufacturers are selective with what they stock, meaning some sizes are available from uncoloured stock (brown) only, green stock only or both.

The sizes stocked tinted or untinted depends on which industry consumes that particular panel size and whether they apply a finish. For example, 4.2m length boards are frequently used by furniture and skirting board manufacturers as they allow long lengths to be cut. These industries also frequently apply a finish, so manufacturers often opt to stock brown, untinted 4.2m MDF.

On the contrary, 2.4m boards are used broadly across a range of building and manufacturing industries, and in applications that do not necessarily need finishing, therefore they default to the traditional green tint for these panel sizes.

Is MR MDF waterproof?

No. MR MDF is moisture resistant not water resistant or waterproof. It is resistant to moisture in humid conditions i.e. water vapour rather than direct contact with water. This means it is suitable for use in kitchens or bathrooms and is resistant to steam generated in those rooms, but being a wood based material MDF will degenerate if in constant contact with water.

Should you require any further information please call us on 01905 621 678.