• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer
DIY Doctor
MENUMENU
  • DIY Doctor menu logo
  • Home
  • DIY Projects
    • All Projects
    • Brick, Block, Marsonary and Concrete
    • Damp, Condensation, Rot and Woodworm
    • Doors, Windows and Conservatories
    • Electrical
    • Fencing, Decking, Paving and Patios
    • Floors, Walls, Ceilings and Lofts
    • Garages, Sheds and Outbuildings
    • Gardening and Landscaping
    • General Building, Self Build and Renovation
    • General Repairs and Cleaning
    • Green Living and Eco DIY
    • Ground work, Foundations and Drainage
    • Heating, Central Heating and Boilers
    • Joinery and Carpentry
    • Materials, Fixings and Fixing
    • Painting, Decorating and Finishing
    • Planning Regs, Project Management and Safety
    • Plastering, Plasterboard and Rendering
    • Plumbing
    • Roofing and Gutters
    • Tiling and Tiles
    • Tools, Appliances and Access
    • DIY Tips
  • UK DIY Forums
  • DIY Videos
    • Bathroom DIY Videos
    • Building Foundation Videos
    • Building Videos
    • Carpentry and Woodworking Videos
    • Damp and Damproofing Videos
    • Decorating Videos
    • Electrical Videos
    • Fitting Blinds Videos
    • Flooring Videos
    • Gardening Videos
    • Green and Eco Friendly Videos
    • Hand and Power Tools Videos
    • Heating and Central Heating Videos
    • Kitchen Videos
    • Plastering and Drylining Videos
    • Plumbing Videos
    • Security Videos
  • Find Tradesmen
    • Find a Tradesman
    • Contract Download
    • Working with Tradesmen - Ultimate Guide
    • Home Improver Protection
    • Price Doctor
  • Tool Store
    • Tool Store
    • Bookstore
    • Tool Reviews and Product Reviews
  • Blog
    • Blog
    • DIY Competitions
  • About us
    • About DIY Doctor
    • What we do
    • Trade Shows and Exhibitions
    • Master Classes
    • Contact Us

Home > DIY How To Projects and Tutorial Guides > How to Paint MDF – Tips and Information on Preparing and Painting MDF Including a Tutorial on the Composition of MDF

How to Paint MDF – Tips and Information on Preparing and Painting MDF Including a Tutorial on the Composition of MDF

Information on how to Prime and Paint MDF correctly. See the right primer and undercoat for painting MDF and achieving a great finish. Learn how to avoid an uneven or blotchy finish on your MDF and discover how MDF is made. Use our tutorial to understand why MDF is a good fibreboard to use in the home and understand why it is very important to seal the timber before installation.

Don't want to do this job yourself? Let us help you find a tradesman local to you

TwitterFacebookPin ItBuffer
Project MenuProject Menu
  • How to Tutorial
  • Video
  • Find Tradesmen
  • Help

Medium Density Fibreboard

Painting MDF or Medium Density Fibreboard is not an easy job. The paint dries so quickly that it can dry in a very uneven and blotchy way. Special primers, such as the one below, are available for MDF and once applied the timber can then be painted with any ordinary paint. The MDF primer seals the timber effectively allowing other paints to dry in a uniform way. We recommend painting the timber with an undercoat, after the primer.

Closeup of mdf fibres

Closeup of mdf fibres that make up the medium density fibreboard

Priming MDF

The surface of MDF, despite it’s density, is very porous. The moisture from ordinary paints is soaked into the MDF very quickly. This leaves a ″skin″ of paint on the surface which, because all moisture has been removed, does not adhere well to the surface. This means that every subsequent layer of paint applied to the MDF is only stuck to the layer (or coat) of paint below it, not to the MDF itself.

This is the reason that, if MDF is not prepared properly, the paint sometimes blisters up resulting in large bubbles on the surface as air (or water) is allowed under the first coat of paint. See the special MDF primers below to avoid this happening to you.

Sanding MDF

Once the MDF has had one coat of primer it is a good idea to put on your mask and give the surface a very light sanding down. Then brush, or hoover off the dust and wipe down with a rag dipped gently (not soaked) in white spirit. This degreases the whole surface allowing the second coat of primer to be applied uniformly and form a great, sealed base for your undercoats and top coats. Remember, any painting is only as good as the preparation that has gone into it.

NOTE: When sanding, whether it’s sanding primer, or the MDF itself and also cutting it, as we state above, always wear a suitable, decent mask! The dust produced by MDF is very bad for you if breathed in so protect yourself!

Painting Both Sides of an MDF Sheet

Because MDF is so porous it is always a good idea to at least prime the underside of the timber before you install it. Water can run from the painted surface, over the edge of the MDF and soak into the unpainted edge.

Finishing the Edges of MDF

The edges of a sheet of MDF are even more porous than the surface of the sheet and over the years there have been many different techniques tried to get a good, even finish on the edges which matches the surface finish.

The best method found by DIY Doctor is to apply an ultra-thin layer of wood filler to the edges, pressed well in with a putty knife or scraper, then sanded down using a sanding block. This prohibits the over-absorption of primer and paint.

Using a Sanding Block

Many people do not put sandpaper onto a sanding block, tradesmen are the worst offenders and we hold our hands up to this. The fact of the matter is that sanding (usually) is to try and get surfaces as flat as they can be so sanding with a a flat surface (IE a sanding block) is really a no brainer….. A human hand, however you contort it, is not flat and the surface you are sanding will never be 100% flat if you use your hand. This applies especially to MDF as the pulp itself is so soft.

Which Primer is Best for MDF?

The two primers below are ideal for MDF and both are stocked in our tool store:

Rustin's MDF Clear Seal

Rustin’s MDF Clear Seal

Blackfriar MDF undercoat

Blackfriar MDF undercoat

MDF is a man-made product constructed from organic wood products which have been broken down into fibres through being pulped and crushed.

Safety Issues With MDF

The resins used to bind MDF often contain Formaldehyde and other compounds which are quite hazardous to health. These compounds can escape into the air when the MDF is being sawn and can even escape from the edges of the timber in it’s free standing, sheet state.

Priming the MDF properly is very important for, as well as sealing it ready for painting, it prevents the compounds being released. It is always a good idea to wear a mask when working with MDF, even if not actually sawing it.

Using all of the Tree for MDF

Firstly the trees (both hardwood and softwoods) are cut down and de-barked. They are then fed into an industrial chipping machine which is the start of the reduction process. None of the timber is wasted as the bark is used for landscaping products and all undersized chips are bonded and sold as wood logs.

The chips are then fed into a screw feeder machine which heats them for 30 seconds to 2 minutes and then they are fed into a machine called a defibrator which grinds the timber down into a pulp while introducing very hot steam to further soften the timber. This entire process is done at a very high pressure.

The pulp is then mixed with wax to allow the very light, very fine fibres to obtain a degree of resistance to moisture. A resin agent is also added to allow the fibres to bond and set together after the timber pulp is fed into giant trays of varying thicknesses and pressed under a very high heat which initiates the resin-bonding process. The resulting sheet is then cut into the required thicknesses and sizes.

MDF then becomes a very uniform wood. Uniform in size and quality with no knots or rings. It is difficult to get a good fixing into the edges of MDF sheets but special coarse threaded screws are available for this.

Benefits of Using MDF

MDF is ideal for the home improver as it works perfectly as a surface for:

  • Veneers – Because MDF is so completely flat with the ability to absorb adhesives, the MDF surface is good for attaching timber, or plastic veneers to
  • MDF is usually less expensive than the timber it is made from on a comparable area price
  • There is no grain. This makes MDF an isotropic timber which gives it consistency in every direction
  • MDF can be curved easily without splitting or cracking in it’s thinner sheet sizes. This makes it ideal for hobby or intricate work
  • Unless it is subjected to a lot of water, MDF will not expand and contract, as timber does, due to the natural moisture content of a normal room at home
  • Having been primed suitably with one of the primers listed above, MDF is very easy to paint as there is no grain or varying surface texture

Drawbacks to Using MDF

There are some drawbacks to using MDF, namely it swells with water and will not return to it’s usual shape. This however is easily overcome by priming and painting correctly to seal the sheet.

All project content written and produced by Mike Edwards, founder of DIY Doctor and industry expert in building technology.

TwitterFacebookPin ItBuffer

Video

Back to the Top

Find a Reliable Local Tradesman

Back to the Top
Don't fancy doing this project yourself? We work with the industries best to ensure that we recommend only reliable and trustworthy tradesmen.
Let DIY Doctor help you find a tradesman

Find a tradesman now!


More Help

Back to the Top
Related Projects That May Help You:
  • Painting Panel Doors – How to Correctly Prepare Timber Panel Doors for Painting and What Order They Should be Painted in
  • Painting a Flush or Flat Door – A Simple Guide to Painting Flush Doors to Get a Great Finish
  • Woodwork Preparation for Painting and How to Paint Bare Wood
  • Painting New Plaster – How to Paint New Plaster and How Long to Wait before Painting Fresh Plaster Using a Mist Coat
  • Painting Kitchen Units – How to Give Your Kitchen a Makeover by Painting Your Worktops, Units, Cupboards and Doors
  • An Explanation of the Various Types of Varnish and Stains – What They do and When to Use Them
  • An Explanation of the Various Types of Paint including When to Use them and How they are Made
  • How to Stain or Dye Over Varnish – Learn how to Prepare an Existing Varnished Surface Correctly so That Wood Stain or Wood Dye can be Applied
  • Learn how to Apply Chalkboard Paint to a Range of Different Surfaces and also how to Prepare Surfaces for Chalkboard Paint
Give us Some Feedback!
Was this page useful:
We read and respond to all feedback by email. To allow us to do so you will be added to our email list, however you can unsubscribe at any time using the links at the bottom of any of our emails. Find out more in our privacy policy. Any DIY questions should be posted to our Forum
Sign me up to the DIY Doctor Newsletter:

Primary Sidebar

DIY Doctor deal of the week

DIY Utility Kit:

Build your own work bench!

RRP Price: £49.99

Special Price: £39.95

Get it here now

See our other deals now!

Master Basic DIY - By DIY Doctor

Our Book - Master Basic DIY

Grab your copy now for all the DIY help you need right at your finger tips!

Buy it Here!

Signup for our Newsletter

Keep up to date with our DIY projects, tips and latest deals

Sign Me Up!

Our Sponsors

Find out about advertising on DIY Doctor

Advert

Other Similar Projects
  • An Explanation Of The Various Types Of Varnish And Stains – What They Do And When To Use Them
  • How To Paint A Panelled Door

Footer

DIY Doctor

Site Menu

  • About Us
  • Contact Us
  • Blog
  • Media/Press
  • Community Work
  • DIY Projects
  • DIY Videos
  • Superstore
  • DIY Tips
  • DIY Suppliers
  • UK DIY Forum
  • DIY Webinars

Other Stuff

  • Advertise
  • Competitions
  • T and Cs
  • Privacy Policy
  • Cookies
  • NHIC
  • Sitemap

DIY Doctor Social Channels

Follow us on Facebook
Follow us on Twitter
Follow us on YouTube
Follow us on Pinterest
Follow us on Tumblr

DIY Doctor are members of:

© DIY Doctor Ltd 2021 All Rights Reserved