Lesson Notes By Weeks and Term v3 - Senior Secondary 3
Differences between shank and bottom filler
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Differences between shank and bottom filler
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Subject: Leather Goods
Class: Senior Secondary 3
Term: 3rd Term
Week: 3
Theme: Footwear Manufacture
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Select the correct type of scouringabrasive. List the methods and equipment for roughing. State the purpose of shank and bottom fillers. Differentiatebetweenshanks and bottom fillers. Carry out the followingoperationssuccessfully:Pounding.Roughing.Marqin.
Footwear Manufacture Differences between shank and bottom filler Term: 3rd Term Week: 4 ---
1. Overview and Learning Objectives This topic focuses on fundamental components used in footwear construction, emphasizing their distinct roles in providing structure, comfort, and durability. Understanding these components is critical for students aspiring to careers in footwear manufacturing, repair, or design within Nigeria's burgeoning leather industry. A solid grasp of these concepts enables the production of high-quality, comfortable, and long-lasting footwear, contributing to local craftsmanship and economic development. Upon completion of this lesson, students will be able to: Identify and select the appropriate type of abrasive material for various scouring tasks in leather work. (Real-world application: Ensuring proper surface preparation for strong adhesive bonds in local shoe repair or manufacturing.) Describe the different methods and identify the necessary equipment for the roughing process. (Real-world application: Preparing components effectively for lasting durability in sandal or shoe production in Nigerian markets.) Explain the specific functions and importance of both shanks and bottom fillers in shoe construction. (Real-world application: Understanding how to build comfortable and supportive shoes for diverse Nigerian users, from daily wearers to industrial workers.) Distinguish clearly between a shank and a bottom filler based on their material, placement, and primary purpose. (Real-world application: Making informed decisions about materials and design when creating or repairing shoes, ensuring product quality and customer satisfaction.) Successfully perform practical operations such as pounding, roughing, and marking the lasting margin. (Real-world application: Developing essential practical skills required for entry-level positions in local shoe factories or establishing personal shoemaking enterprises.)
2. Key Concepts and Explanations This section details the essential concepts required for the lesson, ensuring a comprehensive understanding of each term and process.
A. Scouring Abrasive Definition: A scouring abrasive is a material, typically in granular form, used to roughen or abrade the surface of another material. In leather goods, it is primarily used to prepare surfaces for bonding.
Purpose: To create a textured surface that increases the surface area and provides better mechanical keying for adhesives, ensuring a stronger, more durable bond between components. It removes loose fibres, dirt, and oils.
Types: Commonly refers to sandpaper (abrasive paper) or abrasive wheels/brushes.
Sandpaper: Graded by grit size (e.g., P60, P80, P100, P120). Coarse grit (e.g., P60-P80): Used for initial roughing of tough materials like outsole rubber or thick leather, or for rapid material removal. Medium grit (e.g., P100-P120): Suitable for general roughing of most leather types (e.g., insole, upper components) before cementing. Fine grit (e.g., P180+): Less common for roughing, but can be used for light scuffing or finishing.
Abrasive Wheels/Brushes: Mounted on machines, these provide faster and more consistent roughing for mass production. Examples include wire brushes, nylon abrasive brushes, or carbide-tipped roughing wheels.
Selection: The correct type depends on the material to be scoured (e.g., leather, rubber, EVA), the desired level of roughness, and the subsequent adhesive application.
B. Roughing Definition: Roughing is the process of abrading or scratching the surface of leather or other shoe materials (like rubber soles) to create a coarse texture.
Purpose: To enhance the adhesion of glues or cements by increasing the surface area and creating mechanical interlocking points for the adhesive. Without proper roughing, adhesives will not bond effectively, leading to premature delamination.
Methods:
1. Manual Roughing: Performed by hand using abrasive paper (sandpaper), wire brush, or a rasp. This method is suitable for small-scale production, intricate areas, or repair work.
2. Mechanical Roughing: Utilises specialised machines with roughing wheels (e.g., wire brush wheel, carborundum wheel) or abrasive belts. This method is faster, more consistent, and ideal for industrial-scale production.
Equipment: Hand: Sandpaper (various grits), wire brush, rasp.
Machine: Roughing machine (bench-mounted or industrial stand-alone), equipped with roughing wheels (e.g., steel wire, nylon, carbide), or abrasive belts.
C. Pounding Definition: Pounding, in shoemaking, refers to the process of using a shoemaker's hammer to flatten, shape, and compact various parts of a lasted upper, particularly the lasting margin, or to set tacks and nails.
Purpose:
1. Flattening the Lasting Margin: After lasting, the folded-over lasting allowance (margin) This method is faster, more consistent, and ideal for industrial-scale production.
Equipment: Hand: Sandpaper (various grits), wire brush, rasp.
Machine: Roughing machine (bench-mounted or industrial stand-alone), equipped with roughing wheels (e.g., steel wire, nylon, carbide), or abrasive belts.
C. Pounding Definition: Pounding, in shoemaking, refers to the process of using a shoemaker's hammer to flatten, shape, and compact various parts of a lasted upper, particularly the lasting margin, or to set tacks and nails.
Purpose:
1. Flattening the Lasting Margin: After lasting, the folded-over lasting allowance (margin) needs to be flattened tightly against the insole to remove wrinkles and ensure a smooth, uniform surface for sole attachment. This prevents bulkiness and ensures a clean finish.
2. Shaping and Moulding: To contour the leather to the last, removing any looseness or bagging, especially around the heel seat and toe puff areas.
3. Compacting: To consolidate the fibres of the leather, making it denser and more rigid in specific areas, thereby enhancing the shoe's structural integrity.
4. Setting Adhesives: Sometimes used after cementing to ensure intimate contact and even spread of adhesive.
Equipment: Shoemaker's hammer (e.g., lasting hammer, finishing hammer) with a flat face and a peen.
D. Margin (Lasting Allowance)
Definition: The lasting margin (also known as lasting allowance or lasting edge) is the excess material of the shoe upper that is folded over and cemented or tacked to the insole during the lasting process. It is the part of the upper that extends beyond the feather line of the last.
Purpose:
1. Secure Attachment: To provide sufficient material for securely anchoring the upper to the insole, forming the foundation of the shoe's structure.
2. Strength and Durability: A well-defined and properly lasted margin ensures the upper remains firmly attached to the sole unit, preventing premature separation.
3. Shape Retention: Helps in permanently shaping the upper to the contours of the last.
How to Mark/Determine:
1. Feather Line: The reference point for the lasting margin is the feather line (or lasting line) of the last, which is the edge where the upper meets the sole.
2. Measurement: Typically, a consistent width (e.g., 10-15mm or 3/8 to 5/8 inch) is measured outwards from the feather line around the perimeter of the lasting area (toe, sides, heel).
3. Marking: This measurement is marked with a pencil or chalk, creating a guide for trimming the upper material before lasting, ensuring adequate material for folding without excess bulk.
E. Shank Definition: A shank is a rigid, structural component inserted into the waist area of a shoe, between the insole and the outsole.
Purpose:
1. Arch Support: Provides crucial support to the arch of the foot, preventing foot fatigue and promoting proper foot mechanics.
2. Structural Integrity: Prevents the shoe from collapsing or bending excessively in the waist area, maintaining the shoe's shape and silhouette, particularly in shoes with elevated heels.
3. Weight Distribution: Helps to distribute the wearer's weight evenly across the foot, especially when wearing heeled shoes.
4. Prevents "Broke Waist": Without a shank, the shoe's waist area would flex unnaturally, leading to discomfort and premature structural failure.
Material: Traditionally steel (most common for durability and strength), but also wood, plastic (e.g., hardened fibreboard, ABS plastic), or composite materials (e.g., carbon fibre for lightweight performance).
Placement: Located in the middle portion of the shoe, extending from the heel breast area towards the ball of the foot, specifically under the arch. It sits on top of the insole and beneath the bottom filler (if present) and the outsole.
Shape: Usually elongated and curved to conform to the natural arch of the human foot and the contour of the last. It tapers towards the toe and heel.
Application: Essential in most closed footwear, dress shoes, boots, and especially high-heeled shoes where significant arch support and rigidity are required.
F. Bottom Filler Definition: A bottom filler is a material used to fill the void or cavity created between the insole and the outsole, primarily in the forefoot and waist areas of a shoe (though it does not replace the shank in its structural and curved to conform to the natural arch of the human foot and the contour of the last. It tapers towards the toe and heel.
Application: Essential in most closed footwear, dress shoes, boots, and especially high-heeled shoes where significant arch support and rigidity are required.
F. Bottom Filler Definition: A bottom filler is a material used to fill the void or cavity created between the insole and the outsole, primarily in the forefoot and waist areas of a shoe (though it does not replace the shank in its structural role).
Purpose:
1. Levelling/Filling Voids: Fills the space created by the lasting margin and the uneven surface left after inserting the shank and other components, creating a smooth, level surface for the attachment of the outsole.
2. Cushioning: Provides an additional layer of padding and shock absorption, enhancing wearer comfort.
3. Insulation: Offers thermal insulation, protecting the foot from hot or cold ground temperatures.
4. Moisture Management: Some materials (e.g., cork) can absorb moisture, helping to keep the foot dry and hygienic.
5. Flexibility: Contributes to the overall flexibility of the shoe, depending on the material used.
Material: Common materials include cork compound (granular cork mixed with binder), felt, leather scraps, cellulose board, foam (e.g., EVA, polyurethane), or other resilient composite materials. Cork is highly popular due to its natural cushioning and moisture-absorbing properties.
Placement: Spread or inserted over the entire bottom of the lasted shoe, covering the lasting margin, the top of the shank (if present), and extending into the forefoot area, just below the insole and above the outsole.
Shape: Conforms to the shape of the lasted bottom, often applied as a paste or a pre-cut sheet.
Application: Used in almost all types of footwear to enhance comfort, insulation, and to provide a level surface for the outsole. G. Differences between Shank and Bottom Filler (Comparative Analysis) | Feature | Shank | Bottom Filler | | :---------------- | :--------------------------------------------- | :---------------------------------------------- | | Primary Purpose | Provides rigid arch support; maintains shoe structure and shape; prevents "broken waist." | Fills voids/levels the bottom; provides cushioning, insulation, and flexibility; enhances comfort. | | Material | Rigid materials: Steel, wood, hardened plastic, composite fibre. | Resilient, often granular or fibrous materials: Cork, felt, leather scraps, cellulose board, foam. | | Placement | In the waist area, under the arch, between the insole and outsole. | Spreads over the entire bottom of the shoe, covering the lasting margin and the top of the shank, between the insole and outsole. | | Function | Structural support, rigidity, load bearing. | Comfort, levelling, insulation, moisture absorption, minor cushioning. | | Flexibility | Designed to be rigid and inflexible. | Designed to offer some degree of cushioning and flexibility. | | Essentiality | Critical for structural integrity in many shoes, especially heeled footwear. | Important for comfort and a smooth bottom but less critical for primary structural support than a shank. | | Impact on Shoe | Determines the shoe's longitudinal rigidity and arch support. | Affects the feel, comfort, and internal environment of the shoe. |
3. Teaching and Learning Activities The following activities are designed to engage students practically and conceptually with the topic.
A. Teacher Activities
1. Introduction and Review (10 mins): Begin by briefly reviewing the basic components of a shoe and the lasting process from previous lessons.
Introduce the lesson topic: "Differences between shank and bottom filler," highlighting their importance for shoe quality and comfort. Present the performance objectives clearly to the students.
2. Demonstration of Scouring Abrasives and Roughing (20 mins): Display various types of scouring abrasives (e.g., different grit sandpapers, wire brushes, rasp). Explain their suitability for different materials (leather, rubber, EVA). Demonstrate manual roughing on a piece of scrap leather (upper leather and sole material) using sandpaper and a wire brush. Emphasise the correct technique (even pressure, consistent direction) and the visual/tactile outcome (roughened surface, not torn). If available, demonstrate roughing using a small bench-mounted roughing machine or explain its operation with a diagram.
3. Explanation of Shank and Bottom Filler (25 mins): Present