Lesson Notes By Weeks and Term - Senior Secondary 2

Laundry agents

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Term: 3rd Term

Week: 2

Class: Senior Secondary School 2

Age: 16 years

Duration: 40 minutes of 2 periods each

Date:       

Subject:      Home management

Topic:-       Laundry agents

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to:            

  1. State different, types of laundry agents.                       
  2. Assess the characteristics of laundry agent.                          
  3. Point out the uses of laundry agents.

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION

TEACHER’S ACTIVITY

STUDENT’S ACTIVITY

STEP 1

INTRODUCTION

The teacher reviews the previous lesson on laundry equipment and tools

Students pay attention

STEP 2

EXPLANATION

She discusses the different types of laundry agents

Students pay attention and participates

STEP 3

DEMONSTRATION

She explains the uses and characteristics of laundry agents

Students pay attention and participate

STEP 4

NOTE TAKING

The teacher writes a summarized note on the board

The students copy the note in their books

 

NOTE

LAUNDRY AGENTS

Laundry agents

They are the materials we use in washing our clothes. These materials include: detergents, soaps, water, stain removers e.g. bleach, stiffening agents e.g. starch, whitening agent e.g. laundry blue, disinfectant e.g. Dettol etc.

 

TYPES, CHARACTERISTICS AND USES OF LAUNDRY AGENTS

  1. Detergents

Detergent can be applied to any cleaning agent. Its usage is known generally restricted to those cleaning agents containing significant quantities of a group of chemicals known as surfactants. A number of other chemicals are frequently included to produce a detergent suitable for a specific use.

Essential properties

A good detergent will possess many or all of the following properties:

  1. Reduce the surface tension of water so that the cleaning solution can penetrate the soil and surface.
  2. Emulsify soil and lift it from a surface.
  3. Suspend soil in the cleaning solution
  4. Be soluble in cold water
  5. Be effective in hard water
  6. Be harmless to user and surface to be cleaned
  7. Rinse easily to leave no streaks or scum
  8. Be economical in use.

 

  1. Alkali

Alkalis used in the wash process include
1. Washing Soda (sodium Carbonate Na2CO310H2O) 2. Sodium Phosphate
3. Sodium Hydroxide
4. Sodium Metasilicate
5. Borax (Na2B4O710H2O)
6. Ammonium hydroxide (NH4OH)

The role of the alkali in the wash process

  • Combines with calcium ions in hard water to form water-soluble salts, thus preventing the adverse effects of calcium
  • Enhance the emulsifying and dispersing properties of the detergents

 

  1. Bleaches
  • These are used on white articles only.
  • They remove colouring matter by their oxidizing or reducing action.
  • If not in liquid form, they should be dissolved in hot water in order to ensure that no powder residue remains in the washing machine which may affect later loads.
  • The bleaches commonly used in the laundry process are sodium perborate and sodium hypochlorite (Javelle water).

 

  1. Antichlors

These are agents used to neutralize the chlorine bleach and are essential particularly in the case of polyesters. The use of chlorinated bleaches has a tendency to leave yellow deposits.

 

  1. Sour/acid agents
  • This is used only in industrial laundering in the final rinse, to neutralize any alkaline soap residues that may be present.

       a. Oxalic Acid

  • Sold in white crystals
  • Used for removal of fruit stains, bleaching of brown stains after using potassium permanganate and tannin base of ink stains together with Hydrogen peroxide.

       b. Salt of lemon

  • Salt of Sorrel
  • Compound of Potassium Oxalate and Oxalic Acid referred as Potassium binoxalate
  • Used for neutralizing strong alkali.

       c. Acetic Acid:Removes excessive bluing agents and as a neutralising agents

       d. Oleic Acid

  • Unsuitable for coloured fabrics.
  • Produces soap when mixed with alkali
  • Used for grease and oil stain

       e. Fabric conditioner/Softener

  • A fabric conditioner or softener has surface-active agents like a detergent but they don’t perform the function of cleaning.
  • Fabric conditioners are based on cationic surface-active agents, carrying a positive charge and creates anti-static properties.
  • A fabric conditioner is never used on loads where starch or sizing will be used.
  • The role of the fabric conditioner in laundering
  1. Optical brightener
  • This is an optical brightener/ whitener, which is, in fact, a very fine dye, which gets bleached in course of time.
  • It has a fluorescent effect by reflecting the UV rays of the sun.

The laundry blue in a powder form tends to accumulate in the weave of the fabric and causes it to turn grey and is no longer used in modern laundries

 

  1. Starch
  • This is a stiffening agent used to impart a better appearance to the fabric.
  • The use of starch has declined due to the minimum-iron finishes on fabrics and garments and the reduced use of cotton in favour of man-made fibres.
  • However, there are some articles that have a better feel and drape when starched and it is particularly essential for napkin folds.
  • Since polyesters do not have the ability to absorb starch they are stiffened with sizing agents.

Types of starch

  • Hot-Water Starches
  • Cold-Water Starches
  • Gelatin
  • Glue
  • Synthetic Sizing

 

EVALUATION:    1. List and explain five laundry agents

  1. Discuss the two characteristics each of three of them

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively