In this lab we wanted to find out which concentration of bleach would be best for fading the color out of new denim jeans in ten minutes without causing any damage to the fabric material. We found an overall trend: the higher the concentration of bleach we used, the more faded the jeans would become. Each bleached denim square was rated on a scale of 1 to 10 (10 being completely white and 1 being no color change). The jean squares, which had been soaked in the petri dish containing 100% bleach, had an average of 7.3 on the “color removal scale”. This was the highest average among all the denim squares soaked in varying concentrations of bleach; 50% bleach, 25% bleach, 12.5% bleach, 0% percent bleach (100% water which was used as a control). There was a very visible change in the jeans left in the 100% bleach; most of the darker blue coloring was no longer seen after about two minutes into the bleaching process. It is widely known that bleach is a chemical used to “whiten” or removal color from something, and our experiment confirmed this fact. After the denim squares were soaked in water, the jeans in 100% bleach appeared very faded with little original blue color and had a yellowish tinge as well. In the other bleach solutions, some of the jeans appeared vaguely lighter, and some had no noticeable change at all. The amount the jean squares were faded on the “color removal scale” decreased as the concentration of the bleach decreased. The 50% solution jeans had an average of 5, the 25% bleach soaked jeans had an average of 1.3, followed by 0.6 in the 12.5% bleach. The condition of the jeans was damaged very little in this experiment; the fabric damage reaching a high of 1.3 in the 100% and 50% bleach, and a low of 1 in the 25% and 12.5% bleach. This data support our claim because it is evident from our results that the highest concentration of bleach produced the most faded jeans, which was the desired outcome.
While our hypothesis was supported by our data, there could have been errors due to our mistake in sometimes failing to keep all the constants the same. Possible error may have resulted from the many different pairs of jeans that we used to cut out the denim squares. Each pair of jeans has a unique shade of blue; some jeans that we used in our lab were a very dark wash, and some were a lighter wash. This definitely affected our judgment in how faded each denim square was. The method that we used for analyzing and measuring the results of the experiment is especially prone to observer bias, since the average color removal results were solely dependent on subjective judgment. Due to these errors, in future experiments I would recommend using the same pair of jeans when cutting out the 5x5 cm squares of denim to ensure that each square started out being the same shade. I would also suggest using a scale of 1 to 5 scale instead of a 1 to 10, and clearly defining what would constitute a 1, 2, 3, 4, and 5 to reduce observer bias and make the experiment more repeatable.
This lab was done to demonstrate knowledge of the scientific method; to show that we understood the six different steps and could write a proper hypothesis. From this lab I got an opportunity to practice the scientific method that we learnt in class, and the experiment helped me better understand how to be precise while doing labs as well as being extra cautious while working with chemicals such as bleach. Based on the experience I’ve had with this lab, I now know how to apply the accuracy and careful following of the procedure to other labs in the future. I have also learnt the correct way to form and write a hypothesis in all future labs; using if...then… form and putting the assumptions in the if… part of the hypothesis.
Concentration (% bleach)
|
Average Color Removal (scale 1 to 10)
|
Average Fabric Damage (scale 1 to 10)
|
100
|
7.3
|
1.3
|
50
|
5
|
1.3
|
25
|
1.3
|
1
|
12.5
|
0.6
|
1
|
0
|
0
|
0
|
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