If you’re experimenting with decorative plasters or preparing a professional finish sample for a client, choosing the right board to apply your materials on is crucial. Many beginners (and even experienced artisans) ask the same question:
“Should I use plywood or MDF for plaster-based finishes?”
The answer is simple—MDF (Medium Density Fibreboard) is the better choice. In this post, we’ll break down why MDF boards are the go-to surface for lime-based, microcement, or textured plaster finishes, how to choose the right thickness, where to get them cut to size, and why priming matters more than you think.
Let’s dive into the essentials of getting your base board right—because a smooth, consistent surface is the foundation for a flawless decorative finish.
Use MDF Boards, Not Plywood
While plywood is popular in general carpentry, MDF (Medium Density Fibreboard) is much better suited for decorative plastering work.
Here’s why MDF is the preferred option:
- Smooth surface – Ideal for priming and applying decorative plasters
- No visible grain – You get a clean, professional-looking finish
- Consistent density – Makes troweling and sanding more predictable
Recommended thickness: 9mm or 12mm
These thicknesses strike a good balance between rigidity and ease of handling.
Where to Buy and How to Choose
You’ll find MDF sheets at most hardware stores, builders’ merchants, or home improvement centers. Common sizes include:
- Smaller boards (around 900 x 1200 mm) – Easier to carry and store
- Full sheets (about 2440 x 1220 mm) – Better value if you plan to cut multiple boards
From a full-size sheet, you can typically get 10 to 12 sample boards sized around 600 x 400 mm.
Take Advantage of In-Store Cutting Services
Most hardware or timber suppliers offer a cutting service, which is especially useful if you don’t have tools at home.
- Ask them to cut your MDF into manageable sample board sizes
- You may get a few free cuts depending on the store, with small charges for extras
- Bring your exact measurements—it saves time and ensures accuracy
Tip: A popular sample board size is 400 mm x 600 mm—ideal for testing textures, stencils, or finishes.
Don’t Forget to Prime
Once you have your boards cut and ready, always apply a suitable primer before any plaster. This helps the plaster adhere evenly, reduces absorption, and extends working time.
Whether you’re working with microcement, lime-based plaster, or a textured concrete finish, priming is a step you should never skip.
Final Thoughts
To wrap up:
- Use MDF, not plywood, for sample or finish boards
- Get boards cut to size at the point of purchase if available
- Choose 9mm or 12mm thickness for the best balance of stability and ease
- Prime before plastering for the cleanest and most durable results
Starting with the right board makes everything smoother—from mixing and application to finishing and polishing.