MDF ( medium density fiberboard), can introduce unique challenges for wallcovering installations. The primary problem is that moisture from the adhesive used to secure the wallcovering to the MDF, will be absorbed into the MDF and could cause the board to expand or even explode. When the board expands you can end up with a very ugly install, poor seams, and poor corners. Our recommendations below will help mitigate the challenges, but you should trial them with a qualified installer before proceeding with a large project.
Why is moisture a problem? - MDF is essentially pressurized saw dust. For reference here is the MDF wiki page. The surface of the MDF is quite porous and will absorb water from the adhesive. Too much moisture can cause the board to actually expand or pop. When you install wallcoverings over MDF, ( especially a vinyl wallcovering) the water content in the adhesive can not escape through the vinyl barrier so it will be absorbed into the MDF.
How to manage - the first suggestion is to consider other surfaces. Drywall is a much easier surface to plan a wallcovering installation. But let's assume that you are here because you have no other choice! You must do several things in order to stop the moisture from being absorbed into the MDF board.
Here are our recommendations:
1. fill in gaps in between MDF panels with a product like Durabond - installers would typically call this "mudding" the gap.
2. cover the entire MDF surface, including the "mudd" gaps with a quality sealer / primer. Sealers are available from many brands such as SPS or Rustoleum. We recommend a fast drying sealer like an alcohol based option. Be sure to apply the sealer / primer generously over the gap areas and wherever you think moisture can get into the board.
3. use an EXTRA STRENGTH CLAY adhesive. Clay adhesives are stronger, thicker, and have less water than other clear adhesives. There are several brands selling good Clay adhesives - such as Roman PRO 732
4. DO NOT cut the clay adhesive, adding water is bad, we want to reduce moisture wherever possible.
5. DO NOT use a pasting machine to install - installers like to add water to adhesives to make them run through their pasting machine. Again, water is the enemy here. For this specialty application we recommend using a paint roller and a bucket of clay adhesive. Takes a bit longer but it is the right way.
6. Consider using a SEAM tool to protect the MDF board from being cut into when slitting and installing the wallcovering. Cuts in the MDF surface will make it easy for water to enter the board. Here are 2 links to sources for buying a seam cutting tool - YELLOTOOLS BODYGUARD KNIFE or ADVANCE SEAM BUSTER