Foundry Practice — What Is a Swab Used For in Green Sand Moulding? During pattern withdrawal and mould finishing, which specific task is the swab intended to perform around edges and delicate features?

Introduction / Context:
Foundry hand tools are specialized for distinct tasks. Confusing them leads to mould damage or poor casting surfaces. A swab is commonly used during the delicate moment of pattern withdrawal to protect edges and prevent tearing of the green sand mould.

Given Data / Assumptions:

• Moulding is being done with green (moist) sand in cope and drag.
• Patterns may have sharp edges, fillets, or fine details susceptible to crumbling.
• Tool kit includes swab, slick, trowel, riddle, gate cutter, and brush.

Concept / Approach:
The swab is a small, soft and wet applicator (often cotton or sponge on a stick). Its purpose is to add a controlled amount of moisture to the sand adjacent to the pattern edges. Slight moistening binds the sand locally, increasing cohesion and allowing cleaner draw without edge breakage.

Step-by-Step Solution:
Identify problem: edges crumble when pattern is withdrawn.Apply solution: dampen with the swab along the pattern perimeter and fillets.Effect: improved sand cohesion and reduced scabbing or edge tearing.Hence, the correct function is to moisten the sand around the edge before pattern removal.

Verification / Alternative check:
Standard foundry texts list swabbing as a pre-draw step to ensure a clean release.

Why Other Options Are Wrong:
Smoothing depressions is done with slicks/trowels.Cleaning sand is done with a riddle or screen; a swab does not sieve.Reinforcement of sand uses gaggers or chaplets, not swabs.

Common Pitfalls:
Over-wetting can collapse the mould surface; swab sparingly.

Final Answer:
moistening the sand around the edge before removing pattern