Clean hides and skins form the essential raw materials for leather production, directly influencing the quality and yield of finished leather products. In Kenya's leather industry, proper cleaning of hides and skins immediately after slaughtering is critical to prevent microbial degradation and contamination. This chapter explores the resources involved in cleaning hides and skins, focusing on practical and sustainable methods applicable in Kenyan tanneries and leather workshops.

3.1 Hides/Skins Cleaning Resources

Cleaning hides and skins requires a combination of water, chemicals, tools, and skilled labor to ensure removal of dirt, blood, manure, and other contaminants without damaging the raw material. The availability and quality of these resources in Kenya often determine the efficiency of the curing and subsequent tanning processes.

3.1.1 Water Quality and Supply for Cleaning

Water is the most fundamental resource in cleaning hides and skins. Its availability, quality, and pressure affect the cleanliness and preservation of raw materials in Kenyan tanneries.

Water Quality Parameters

• Potable and Clean Water: Water should be free from harmful microbes and chemicals that can accelerate hide degradation. For instance, at a leather processing facility in Eldoret, reliance on borehole water with low mineral content has reduced hide spoilage compared to surface water sources.
• pH Level: Water with a neutral to slightly alkaline pH (6.5 to 8.5) is preferred since acidic water can cause premature damage to collagen fibers in hides.
• Hardness: Excessively hard water containing high calcium and magnesium can affect the uptake of chemicals during tanning, thus soft water is ideal for cleaning.
• Temperature: Warm water (around 25-30°C) improves the removal of fats and blood stains but must be controlled to avoid microbial growth.

Water Supply Considerations

• Adequate Volume: Large volumes are required during soaking and washing steps. County government abattoirs supplying hides to local tanneries in Nakuru have invested in water recycling systems to reduce consumption.
• Pressure and Flow Rate: High-pressure hoses facilitate efficient removal of dirt and debris without mechanical damage to the skin surface.

3.1.2 Cleaning Chemicals and Agents

Chemical agents complement water in removing organic and inorganic impurities from hides and skins. The choice and concentration of chemicals must balance cleaning efficacy and preservation of hide integrity.

Common Cleaning Agents

• Detergents and Soaps: Mild detergents help emulsify fats, oils, and grease present on skins. At a SACCO-owned tannery near Kisumu, biodegradable detergents are preferred to reduce environmental pollution.
• Sodium Chloride (Salt): Used both as a curing agent and in cleaning to reduce microbial load by osmotic action.
• Alkaline Agents (e.g. Lime): Lime softens the skin and helps remove hair and epidermis. It also raises pH, creating an environment unfavorable for bacteria.
• Enzymatic Cleaners: Proteolytic enzymes break down proteinaceous dirt without harsh abrasion, increasingly used in modern Kenyan leather processing plants.
• Disinfectants: Chemicals such as formaldehyde or phenolic compounds are applied in small quantities for microbial control, especially in wet markets supplying raw hides.

Handling and Environmental Impact

• Chemical Concentrations: Overuse can weaken the skin structure or cause environmental harm when effluents are discharged untreated.
• Safe Storage: Chemicals must be stored in labeled containers away from moisture and heat to maintain effectiveness and safety for workers.

3.1.3 Tools and Equipment for Cleaning

The manual and mechanical tools utilized during cleaning affect the efficiency and quality of hide preparation. Proper equipment minimizes physical damage and accelerates cleaning operations.

• High-Pressure Hoses: Used to rinse hides thoroughly, especially effective in county government abattoirs where large volumes of hides are processed.
• Scrubbing Brushes: Workers at leather cooperatives in Meru use brushes to manually clean skins, which demands skill to avoid damage.
• Soaking Vats: Large-scale tanneries in Nairobi use vats to soak hides in water and chemicals, ensuring even cleaning.
• Mechanical Scrapers: These tools facilitate hair removal during beamhouse operations, commonly employed in modern processing plants.
• Water Pumps: Essential for maintaining continuous water supply, especially in remote areas where water pressure is low.

3.1.4 Skilled Labor and Operational Practices in Cleaning

Human expertise plays a vital role in the effective use of cleaning resources, ensuring hides and skins are cleaned without compromising quality.

Skill Requirements

• Knowledge of Hide Anatomy: Understanding grain and flesh sides helps workers apply cleaning methods that preserve structural integrity.
• Chemical Handling: Training on appropriate chemical dosages and safety prevents skin damage and ensures worker safety.
• Equipment Operation: Skilled use of scrapers, hoses, and soaking vats reduces physical damage and increases cleaning efficiency.
• Microbial Control Awareness: Workers trained in hygiene reduce cross-contamination risks, crucial in facilities supplying leather for garment manufacturing.

Operational Practices

• Sequencing Cleaning Steps: Soaking, washing, liming, and dehairing must follow a strict sequence to optimize cleaning and preservation.
• Regular Maintenance of Equipment: Prevents contamination and ensures consistent performance.
• Waste Management: Proper disposal or treatment of effluents protects the environment and complies with Kenyan regulations such as those enforced by NEMA.

At a leather processing cooperative in Nakuru, adoption of standard operating procedures for cleaning has led to a 20% reduction in hide rejection rates due to contamination or damage.

Chapter Summary

This chapter explored the essential resources required for cleaning hides and skins, emphasizing the importance of selecting appropriate materials to ensure effective processing. Detergents were discussed as key agents in removing dirt and contaminants, with attention given to their types and applications. The role of fresh water was highlighted as a critical component for rinsing and maintaining cleanliness throughout the curing process. Standard cleaning procedures for hides and skins were outlined to establish consistent quality and hygiene. Prior to preservation, several preparatory processes were necessary to ready the material, including thorough washing to eliminate residual impurities. Fleshing was detailed as a vital step in removing excess flesh and fat from hides and skins, which enhances preservation efficacy. Finally, trimming was presented as the finishing process that shapes and sizes the hides or skins, ensuring they meet the required standards for further use or sale.