EXPERIMENTAL: AN INVESTIGATION INTO SOME VARIABLES INVOLVED IN THE
CLEANING ACTION OF COMMERCIALLY AVAILABLE SOAP POWDERS AND DETERGENTS
Introduction Washing products were introduced to simplify the chore of washing clothes. Since their introduction, manufacturers have continuously attempted to persuade the general public that their particular product is, in some way or another, «best». However, «best» may refer to: value for money; and/or washes clothes the cleanest; and/or colour fastness; and/or the inclusion of a free measuring cup or a plastic toy; and/or biological action (i.e., the product contains enzymes which speed up the washing process at low temperatures); and/or environmental friendliness (i.e., the product is biodegradable); and ...........................?
Surprisingly, perhaps, manufacturers do apply the scientific method to support their claims - even if their choice of variables is, on occasions, a shade selective ...
In this investigation, you are required to examine at least three   
variables involved in the cleaning action of one or more washing
products; two of these must be independent variables.
Notes
1.  Apart from your notes and standard textbooks, useful sources of
information might include the labels on washing products and fabrics;
it is good practice to include a bibliography in your write-up.
2. You are provided with a variety of washing products, fabrics, and stains. In addition, you will need to use - within reason - suitable apparatus.
3. The proposed plans of your investigation should be presented in detail; these plans may be modified as a result of trial or complete sets of experiments.
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