Lime Plaster Course

Lesson 1 • Health, Safety, and Regulatory Basics

Covers caustic hazards, PPE requirements, and compliance with workplace safety standards. Ensures students work safely before handling any materials.

Lesson 2 • Lime Chemistry Fundamentals

Explains the calcination, slaking, and carbonation cycle of lime. Connects chemical behaviour to practical mixing and curing decisions.

Lesson 3 • Aggregates and Additives Overview

Introduces sands, pozzolans, fibres, and pigments used in lime plaster mixes. Establishes how each component affects workability and durability.

Lesson 4 • Types of Lime and Their Properties

Distinguishes quicklime, hydrated lime, hydraulic lime, and lime putty. Students select the correct lime type for a given application.

Lesson 1 • Hand Tools for Lime Plastering

Covers trowels, hawks, floats, and scratching tools specific to lime work. Students match each tool to its function in the plastering sequence.

Lesson 2 • Mixing Equipment and Gauging Tools

Introduces paddle mixers, mortar tubs, and measuring equipment for consistent batches. Accurate gauging prevents mix failures and waste.

Lesson 3 • Workspace Preparation and Protection

Teaches masking, dust sheeting, and environmental controls before plastering begins. Protects adjacent surfaces and maintains curing conditions.

Lesson 1 • Identifying Common Substrates

Distinguishes masonry, timber lath, metal lath, and existing plaster backgrounds. Substrate type determines preparation method and mix design.

Lesson 2 • Cleaning and Repairing Substrates

Removes contaminants, loose material, and efflorescence before plastering. Repairs ensure a stable, uniform base for new lime coats.

Lesson 3 • Assessing Substrate Condition

Uses visual inspection, tap testing, and moisture meters to evaluate background integrity. Findings directly inform repair and priming decisions.

Lesson 4 • Installing Lath and Reinforcement

Covers fixing timber lath, metal lath, and fibre mesh to create mechanical keys. Proper installation prevents delamination and cracking.

Lesson 1 • Principles of Mix Proportioning

Explains binder-to-aggregate ratios and how they affect strength, flexibility, and porosity. Ratio selection is the foundation of every mix decision.

Lesson 2 • Float Coat Mix Design

Develops intermediate mixes that level the surface and regulate suction for the finish. Float coat mix must balance strength and compatibility with the scratch coat.

Lesson 3 • Finish Coat Mix Design

Creates fine, workable mixes for the final decorative or functional surface. Finish mixes prioritise smoothness, colour consistency, and breathability.

Lesson 4 • Batching, Mixing, and Quality Control

Applies consistent batching procedures and on-site quality checks to every mix. Repeatable batching eliminates colour variation and structural inconsistency.

Lesson 1 • Scratching and Keying the Surface

Creates mechanical keys in the scratch coat surface before it fully sets. Correct scratch depth and pattern maximise bond for the float coat.

Lesson 2 • Loading and Throwing Techniques

Develops the physical skill of loading a hawk and throwing plaster onto the wall. Efficient loading and throwing reduce fatigue and improve coverage.

Lesson 3 • Curing the Scratch Coat

Manages moisture retention and environmental conditions during scratch coat curing. Proper curing prevents premature drying, cracking, and weak carbonation.

Lesson 4 • Ruling Off and Levelling

Uses screeds and darbies to bring the scratch coat to a flat, plumb plane. Accurate ruling off at this stage simplifies all subsequent coats.

Lesson 1 • Floating and Closing the Surface

Uses wood and sponge floats to consolidate the float coat and close the surface texture. Float timing relative to set determines the texture achieved.

Lesson 2 • Trowelling and Burnishing Finishes

Develops steel trowel technique to close, polish, and burnish lime finish coats. Trowel pressure and timing control the final sheen and density.

Lesson 3 • Applying the Finish Coat

Spreads the fine finish coat in thin, even passes over the prepared float coat. Thin application and controlled trowelling produce a smooth, consistent surface.

Lesson 4 • Textured and Decorative Finish Options

Introduces scraped, sponged, and brushed textures achievable with lime finish coats. Students produce at least two distinct finish textures on practice panels.

Lesson 1 • Understanding the Carbonation Cycle

Explains how CO2 absorption converts calcium hydroxide to calcium carbonate over time. Understanding this cycle informs all curing and protection decisions.

Lesson 2 • Diagnosing Common Defects

Identifies cracking, delamination, efflorescence, and staining by cause and appearance. Accurate diagnosis is required before any repair is attempted.

Lesson 3 • Final Inspection and Quality Standards

Uses straightedges, raking light, and moisture meters to verify finished work quality. Students apply industry quality benchmarks to accept or reject their own work.

Lesson 4 • Environmental Control During Curing

Manages temperature, humidity, and airflow to optimise carbonation and prevent defects. Environmental control is the primary variable in curing success.

Lesson 1 • Venetian Plaster and Marmorino

Applies polished lime finish systems including Venetian plaster and marmorino techniques. These systems require multiple thin coats and precise burnishing control.

Lesson 2 • Lime Plaster in Wet Areas

Adapts lime plaster systems for bathrooms and kitchens using hydraulic lime and additives. Moisture management and surface sealing are critical in wet environments.

Lesson 3 • Heritage and Conservation Plastering

Matches historic plaster profiles, mixes, and textures for conservation projects. Students apply conservation ethics and material compatibility principles.

Lesson 4 • Ornamental and Moulded Lime Work

Produces run mouldings, cast ornaments, and enrichments using lime-based materials. Ornamental work requires precise mix control and tool-making skills.