How to waterproof MDF sheets

Protect your MDF from moisture penetration

MDF sheets are commonly used to build all sorts of furniture as they are among the cheapest alternatives to wood. It is also very smooth and its surface is consistent, making it ideal for painting as well as when one needs to cut designs which are a bit more detailed. However, before starting to build anything with them, it is a good idea to waterproof MDF sheets. In such a way you would be protecting the sheets from getting damages should they be exposed to water, or moisture. Even though it is a known fact that MDF furniture should not be fitted in a bathroom, for instance, accidents may still happen, such as in the case of spillages and flooding. Hence, it is always a good idea to waterproof MDF sheets so as to reduce the possibility of having such furniture ending up useless or badly deformed once it is exposed to moisture or water.

Water can quickly and easily destroy MDF sheets. Image credit: Popular Woodworking

Waterproofing with paint

Various different types of sheets can be bought from an MDF supplier. It is also easy to find waterproof MDF sheets, which have already undergone the waterproofing process. However these will be more costly than normal MDF sheets. In reality you can waterproof your MDF sheets yourself quite easily and effortlessly.

In fact, waterproofing MDF sheets is neither difficult nor time consuming, and this is just what we shall be discussing hereunder. All it takes is painting the surface area of the MDF boards. One should use a moisture-resistant type of paint so as to create a permanent layer of waterproofing over the MDF sheet.

So basically you will need to buy moisture-resistant paint and later primer. You will also need a roller tray, roller tray liner, a roll cover, and a paintbrush. Simply insert the paint roller into the cover. A 3/8 inch roller cover is generally recommended for this job as it provides a good coverage of the paint onto MDF boards. Place the roller tray liner into the tray, and pour later primer into it. Then, start to apply the primer to the MDF board by using the paint roller. It is important that you allow the primer to dry well. It is best to allow at least six hours to pass.

Make sure you clean all the tools with water so as to remove the primer from the roller and the roller covers. Clean them well so as to be able to use them again later. Next, place the roller cover onto the paint roller, and a new layer of liner in the roller tray.

Now you can paint the boards with the moisture-resistant paint. For the edges you will need to use a paintbrush. The rest of the MDF boards can be painted quickly by using the paint roller. Allow the paint to dry for about four hours. Then it is best to apply a second layer of paint. In this way the coating is more properly applied and the boards will be well covered and waterproofed. Let the last layer of paint to dry for at least three days for best results. From then onwards you may allow your MDF boards to be used near areas where moisture is a bit high.

Adding waterproof sealant to MDF is easy. Image credit: Fine Woodworking

Waterproofing with sealant

Another way is to waterproof MDF boards by using a high quality wood sealant or stain. These are highly water repellent and so they will help the MDF boards to withstand moisture as well as humidity. Such sealants, stains and varnishes have the advantage of coming in various different colors. So it is also a good way to make your MDF boards get the color that you want, while also waterproofing them. MDF is often not considered to be ideal for exterior use. However there are some products which offer an all-year protection for exterior MDF. These offer a guaranteed protection against the elements, including rain and even sunlight. Once the sealant has been applied, it is always best to allow that layer to dry well and apply another coating, for best results.

By following these simple steps you can easily waterproof your MDF boards. From then on you are all set to start using those boards for your woodworking or DIY projects. As you can see there is no need to buy readily waterproofed MDF boards as you can easily waterproof them yourself in a very simple process that basically only involves some painting. The products are not that costly either, and they will make up for their cost when you consider how more resistant your MDF is going to be afterwards.