Plastering Basics: Understanding the Fundamentals

Plastering is a skill that takes years to master, but understanding the basics helps with preparation, small repairs, and communication with specialists.

Types of Plaster

• Undercoat (browning): First coat on masonry, builds thickness
• Bonding: For smooth or less absorbent surfaces
• Finish coat: Final thin layer, produces smooth surface
• One-coat: Undercoat and finish combined for DIY
• Gypsum-based: Standard interior plasters

Surface Preparation

Plaster adheres to clean, stable surfaces:

• Remove loose material
• Apply PVA or bonding agent to smooth surfaces
• Wet masonry to control suction
• Fix any structural issues first

Mixing Plaster

• Add plaster to water, not water to plaster
• Mix to smooth, lump-free consistency
• Use within working time (varies by type)
• Mix only what you can use

Application Basics

General plastering technique:

1. Load hawk with plaster
2. Transfer to trowel
3. Apply in firm upward strokes
4. Build even thickness
5. Work systematically across the area

Finishing

Creating a smooth finish:

• Wait for plaster to "take up"
• Splash with water and trowel to polish
• Multiple passes as it sets
• Fill any hollows in later passes
• Final polish when firm but not set

Common Mistakes

• Plaster too wet or dry
• Working too long after setting begins
• Uneven thickness causing cracking
• Insufficient surface preparation
• Poor mixing leaving lumps

Repair Work

Small repairs are more manageable:

• Cut back damaged area to sound plaster
• Undercut edges for key
• Apply bonding agent
• Build up in layers if thick
• Feather edges to surrounding surface

When to Call a Pro

Full room plastering requires:

• Years of practice for good results
• Speed to complete before setting
• Consistent technique across large areas
• Understanding of different substrates

Small patches are learnable; full rooms need specialists.