18mm - Moisture Resistant MDF

Medium Density Fibreboard, more commonly referred throughout the United Kingdom as just MDF, is an engineered wood product manufactured predominantly using softwood timber (virgin and recycled). Although some MDF sheets, (normally ones that are imported into the UK), have been known to contain hardwood timber fibres in the panel as well.

As far as we understand, all the UK manufacturers basically use the same process. Initially starting with the logs (unless it’s recycled timber obviously) , these are stripped of all their bark, sent through to a chipper machine which reduces the timber into small chips, the next stage involves a defibration machine which then reduces these chips into small fibres. These fibres are then combined with wax and a resin binder. Then under high temperature and pressure the panel is manufactured into the sheet material we are all familiar with.  

Although it seems to get lost by using the acronym MDF, Medium Density Fibreboard is obviously defined by density, although each manufacturer will have its own criteria for density in each of its own manufactured MDF panels, you can use the following as a rough guide.

1. M.D.F (Light Weight )                                                    580/600 D
2. M.D.F (Standard Grade)                                                630/680 D
3.  HDF (High Density Fibreboard)                                  680 D & above

I.E. 600 D = 600 kilogrammes per m³.

We also have to remember that MDF is only a generic term and doesn't actually apply to a single product. To actual specify a product correctly; you need to add which type of MDF you require. For example you could choose from the following : Standard Grade MDF, Light Weight MDF, Ultralite MDF, Zero Formaldehyde (ZF), Moisture Resistant MDF (MR), Fire Retardant MDF (FR), Exterior MDF, In the case of HDF, this does just apply to a Standard Grade High Density Fibreboard currently.

Although this is entirely our own opinion, We've always thought Light Weight MDF, should be referred to as LDF (Low Density Fibreboard) or even Light Weight LDF to fit in with the other two MDF terminologies. We're presuming from a marketing point of view, it’s easier to visualise what is meant by Light Weight MDF, than Low Density MDF. But it’s always made us smile as it seems to be a contradiction to say Light Weight and Medium Density Fibreboard (MDF) in referring to this single product.

Regarding Moisture Resistant MDF, the following properties can be assigned to this MDF sheet material in relation to all United Kingdom (UK) and Republic of Ireland manufacturers.

1. Both Kronospan and Caberboard (Norbord) produce their MR MDF with a green dye throughout the sheet material to signify that those boards are moisture resistant. Medite (Coiltte) on certain thickness produce their MR MDF in a sandwich composition. With the outer faces beige in colour and a larger core dyed green to help identify this sheet material as moisture resistant. Thinner boards within the Medite range are the same as the other two UK manufacturers and are dyed green throughout. (Please visit the knowledge base tab, located on the top menu bar, for each manufacturers own technical / specification / health and safety PDF's)
2. Is manufactured and certified to FSC classification (Forest Stewardship Council). So you can be confident that the timber used in the manufacturer of the MDF panel comes from a well-managed, sustainable source. And the MDF sheet material can be traced from the forest to the end user. (Please note all companies involved in the handling of the Standard Grade sheet material, upto the end user must be FSC certified. Otherwise the chain is broken and traceability, FSC certification stops at the last company that is FSC certified.)
3. Due to the manufacturing process, Moisture Resistant MDF is free from knots and other defects normally seen in plywood etc. And benefits from having a smooth hard surface which is ideal for general joinery / shopfitting applications. Excellent painting properties. And is used widely for veneering and laminating onto. Also obviously due to it's moisture resistant properties, this type of MDF can be used in areas you wouldn't use or consider using standard grade mdf.