My Final SIP report

Here's my long-awaited SIP report -- A culmination of weeks of hard work and perseverance! :D I'm very pleased to report a turnitin similarity rate of only 1%,which should actually have been ZERO, seeing that 'the purpose of this investigation is to find out' was deemed as plagiarism !?! Gah! ><

I apologize for some aberrant formatting here and there, which I cannot seem to alter! I also had to resort to taking a screen shot of my graphs (results), as I was unable to cut and paste them onto the post. :(

Otherwise, the report is more or less intact.

Abstract

Stains are a relevant part of our lives. Numerous methods of stain removal have been advocated, with varying success. The purpose of this experiment is to determine which home remedy cleaning agent is the best all-purpose stain remover for four common types of stains - protein, tannin, oil and dye stains. Each agent – vinegar, baking soda, lemon juice and hydrogen peroxide, is used to clean all four stains individually. The rankings for stain colour and stain area reduction were used to gauge the efficacy of stain removal, and analysed with the Spearman Rank Correlation Coefficient. Of the cleaning agents tested, there appears to be no ‘all-in-one’ home remedy stain remover which best removes each of the common stain types. For practical purposes, the approach is to target specific stains with specific stain removers. The results suggest that for protein, dye and oil stains, baking soda is the best cleaning agent, while hydrogen peroxide is the best for tannin stains.

Introduction

It is well known that stains, especially once set, are notoriously hard to remove. Hence the ubiquitous sprouting of numerous laundry detergent commercials claiming to be able to remove all types of stains effectively. Yet others swear by the more ‘traditional’ methods of using home remedies like vinegar, sodium bicarbonate, lemon juice and hydrogen peroxide. Taylor (1999) claims vinegar to be a multi-purpose ‘miracle’ cleaner, while the Massachusetts Water Resource Authority (2005) promotes freshly squeezed lemon juice, baking soda and hydrogen peroxide as environmentally-friendly and effective all-purpose cleaners (including laundering), in its guide to reducing hazardous household products. Furthermore, it also mentions that the toxic chemicals found in every household are thrice as likely to cause cancer, than environmental airborne pollutants, hence advocating the use of home remedy, rather than commercially synthesized cleaning agents. Despite this relentless onslaught of claims, skepticism still prevails, as current literature presents conflicting ideas and noticeable gaps in existing knowledge in the field of stain removal and stain chemistry, which has great relevance and practicality in real-life situations.

Hence, the purpose of this investigation is to find out which home remedy is the best for common stain removal, leading to the research question: Which home remedy cleaning agent is the most effective all-purpose stain remover for the four common types of stains - protein (animal source), tannin (plant source), oil and dye stains? The hypothesis is that hydrogen peroxide is the best, home remedy all-purpose stain remover for protein, tannin, oil and dye stains. This hypothesis was formulated after research revealed that 3 inventions which target general stains, by You & Siklosi (1983), Mitchell, Carty & Zielske (1988) and Chung & Spadini (1999), all incorporated hydrogen peroxide as their main component, capitalising on its bleaching actions to reduce stain area and to lighten stain colour.

This two-pronged experiment tests the stain-removing efficacy of 4 home remedy cleaning agents, vinegar, baking soda (sodium bicarbonate), lemon juice and hydrogen peroxide on each of 4 common types of stains (protein, tannin, oil & dye). Each cleaning agent is used to clean all 4 stains individually in 4 separate experiments. The independent variable for this is the type of cleaning agent used to soak stains before rinsing with water. On the other hand, each stain type is treated separately with 4 different agents, making the independent variable for this prong the type of stain used. The results of these two prongs are combined to draw a conclusion. The dependent variables are the difference in stain colour (colour chart) before and after cleaning and the difference in stain size (using quadrat to quantify) before and after cleaning. The controlled variables are as follows:

Surface	Staining agent	Cleaning agent	Location
Colour before staining (pure white)	Amount applied: 0.2mls	Amount applied: 15mls	Study room
Material (cotton/polyester)	Time for setting: 3 days	Soaking time: 10 minutes
Smooth and flat for easy application and stain setting	Method of application: Drip staining agent over centre of cloth and allow stain to spread spontaneously	Application method: Pour agent into bowl; ensure stain is completely submerged
	Same concentration (same source)	Temperature of water used to wash off stains: 26°C
	Same temperature (26°C)

Apparatus and Materials

1) 4 home remedy cleaning agents (Fig.1): 180mls Heinz distilled white vinegar (5%), 180mls hydrogen peroxide (3%), 180mls lemon juice (freshly squeezed, then strained) and 180mg baking soda (pure sodium bicarbonate powder) *A 1:1 paste (recommended by home cleaning websites for laundering) of 15g baking soda is evenly mixed with 15mls water (Fig.2). The stains are left to soak in the paste.

2) 4 staining agents: 3mls of black coffee for tannin stain, 3mls of beef meat juice for protein stain, 3mls of blue ink for dye stain and 3mls of laksa oil for oil-based stain.

3) Colour chart (http://www.pagetutor.com/common/bgcolors1536.html) (Fig.3)

4) Quadrat (to calculate stain area) (Fig.4)

5) Syringes for volume measurement (Four 5-cc & three 20-cc syringes)

6) Kitchen scale (to weigh out baking soda)

7) 60 pieces of 10 x 10cm white cloth

8) 15 paper cups, 20 paper bowls

9) 15 rubber bands

10) Laboratory thermometer

11) Tap water (room temperature of 26°C)

12) Strainer

13) Camera

Methodology

1) On the top right-hand corners, pencil was used to label the cloths C (coffee), M (meat juice), B (blue ink) and L (laksa oil) until 15 of each were obtained.

2) On the right of each label, V1, V2, V3 (vinegar), B1, B2, B3 (baking soda), H1, H2, H3 (hydrogen peroxide), L1, L2, L3 (lemon juice) and W1, W2, W3 (water only) was added respectively. The experiment was done thrice to reduce the chance of experimental errors. The ‘1’, ‘2’ and ‘3’ labels represent the first, second and third experiments respectively. The table below illustrates the labelling used for Experiment 1:

Stain a	White vinegar	Sodium bicarbonate	Hydrogen peroxide	Lemon Juice	Water (control b - no cleaning agent)
Coffee	CV1	CB1	CH1	CL1	CW1
Meat juice	MV1	MB1	MH1	ML1	MW1
Blue ink	BV1	BB1	BH1	BL1	BW1
Laksa oil	LV1	LB1	LH1	LL1	LW1

^a As a control for the stains, cloths that were not stained were washed in the 4 cleaning agents.

^b As a control for the 4 cleaning agents used to soak the stain before rinsing with water, stained cloths that were not soaked in the any of the agents were rinsed off with water at the end of the setting time.

3) Each cloth was placed over the rim of a paper cup and secured with a rubber band, so that the stains could be properly applied on a smooth, flat surface (Fig.5).

4) Experiments were carried out one stain at a time to reduce risk of cross contamination.

5) For the coffee stain, a cup of black coffee was made using 3 teaspoons of Arabica coffee powder and 200mls of water. It was left to cool to room temperature (26°C) before staining.

6) 0.2mls* of coffee was drawn into the 5cc syringe, ensuring that there were no air bubbles trapped within (Fig.6) & there was no parallax error (eye was kept level with syringe marking).

* This was an arbitrary amount which could give an appropriate-sized stain area for testing.

7) Coffee was dripped onto the centre of the cloth and allowed to spread on its own.

8) This was repeated until all 15 cloths labelled C (for experiments 1, 2 and 3) had been stained. Staining for each of the 3 experiment sets (1 set = 5 cloths) was staggered 20 minutes apart, and the timings recorded for accurate duration of setting. After setting, there was 20 minutes in between experiment sets to wash the 5 cloths in each set.

9) The stains were left to dry and set for 3 days (Fig.7) in the same location (study room).

10) After the stains had set, the cloths were removed from the cups and photos taken.

11) A quadrat was used to calculate the area of the stains (to nearest half grid) (Table 1C).

12) The initial stain colour was colour coded with one on the colour chart (Table 1C).

13) Each cloth was placed in a bowl as shown to soak the stain (Fig.8).

14) 15mls* (with 20cc syringe) of the respective cleaning agents was added into the corresponding (labelled) bowls, ensuring that the stains were all fully submerged (Fig.9).

* An arbitrary amount which was pre-tested to be able to fully submerge the stains in bowls.

15) The stains were left to soak thoroughly for 10 minutes.

16) After 10 minutes, each cloth was place in a basin of tap water and left to soak for fifteen minutes (Fig.10) before being hung to dry (Fig.11).

17) Photos of the dry cloths were taken under white light, with curtains drawn.

18) A quadrat was used to calculate the area of the stains left behind (Table 1C).

19) Cloths were examined under white light and against a white background. Using the initial stain colour matched with the colour chart as a comparison, the number of levels of colour reduction was recorded and ranked according to the degree of staining left behind. The greater the level of colour reduction, the higher the ranking accorded (Table 1C).

20) The results of experiments 1, 2 & 3 were collated separately (Table 1C) and combined to obtain an overall ranking for each cleaner (Table 2C). The cleaning agent with the highest rank was the most effective in cleaning coffee stains.

21) Steps 5 -20 were repeated for each of the other stains – meat juice (M), blue ink (B) and laksa oil (L). The data was tabulated in Tables 1M, 2M, 1B, 2B, 1L, 2L and analysed.

* Meat juice was obtained by milking a slab of raw beef steak; the blue ink source was Shiny oil-based stamp ink; the top layer of oil from room temperature (26°C) laksa gravy was used.

22) The Spearman Rho coefficient was computed for each stain group (Table 3s), using the rank orders from the 2 dependent variables - stain area and stain colour reduction.

23) Using the final scores obtained from all experimental sets, the cleaning agent with the best overall combined ranking score (Table 4) is the most effective home remedy, all-purpose stain remover for the 4 common stain types tested.

Results

The results of this experiment revealed that baking soda was the most effective stain remover, in terms of reduction in stain area and stain colour, for 3 of the 4 stains tested –

protein, dye and oil (Graph 1), with hydrogen peroxide ranking second for the same 3 stains. For tannin stains, hydrogen peroxide was the most effective cleaning agent, with baking soda being the worst. Lemon juice and vinegar were less effective than baking soda and hydrogen peroxide for protein, dye and oil stains, but more effective than baking soda for tannin stains. Water alone (control) was the least effective in removing tannin, dye and oil stains, but was more effective than vinegar and lemon juice for protein stains.

Graph 2 shows strong positive Spearman rho rank correlations between stain area and stain colour reductions for all 4 stains tested, with oil showing a perfect correlation.

Table R shows that the home remedy cleaning agents which remove common stains most effectively are baking soda and hydrogen peroxide, followed by lemon juice and vinegar. Water alone is the least effective for all 4 stains.

Discussion

Stain removing methods abound, with various stain removers working differently on varying stains. How effectively a stain is removed depends on the size, polarity and solubility of the molecules in both the stain and the stain remover. Generally, the concept of ‘like dissolves like’ can be applied – inorganic solvents dissolve inorganic compounds while organic solvents dissolve organic compounds. Alternatively, if one knows if a stain is acidic or alkaline, one can neutralize it with an opposite product. Stain removers work in 3 ways – by dissolving, breaking up (enables stains to be rinsed off easily) or masking the stain.

The results suggest that hydrogen peroxide and baking soda are generally both effective stain removers for most common stain types. However, there does not appear to be a true, ‘all-in-one’, all-purpose stain remover, which works best for every type of stain.

Baking soda or sodium bicarbonate is a weak alkaline in aqueous solution This alkalinity raises the pH of acidic stains like protein, dye (oil-based) and oil, neutralising them and making them easier to wash off, hence accounting for its efficacy in removing these stains. Bases also alter the secondary and tertiary structures of proteins by breaking up their ionic salt bridges and disulphide bonds. This denaturation causes protein to coagulate into a semi-solid gel by trapping water within, hence dislodging stain particles from the fabric. A dye has 2 distinct parts: a chromophore (colour-bearing part of molecule) and a reactive system which forms covalent bonds with the material. Alkali hydrolyses the oxygen bridges between the reactive system and the chromophore, loosening their hold on the fabric and enabling the stains to be washed off. The alkaline paste absorbs oil and excess moisture when applied to the laksa oil stain, allowing the oil to be removed when the paste is rinsed off with water. Coffee comprises mainly hydrolysable tannins, with some condensed tannins. The former are hydrolysed by weak bases to produce carbohydrates and phenolic acids, both of which are water-soluble. Condensed tannins are insoluble and are not cleaved by bases, which is why part of the tannin stain remains. Alkalis are also known to set tannin stains, which was why baking soda was less effective than acidic vinegar and lemon juice.

Hydrogen peroxide is an oxidising bleach which works mainly by removing colours through breaking the chemical double bonds of chromophores (colour-bearing molecules), hence lightening stains. Chromophores are present in anything with colour, like stains. This bond destruction alters the structure of chromophores, changing their optical properties and rendering them incapable of absorbing light in the visible spectrum, hence making them colourless. An oxidizer does not actually eradicate the staining material but only makes it less visible by changing the chemical makeup. Moreover, oxidation reactions give off oxygen which rises to the top of a solution, dislodging parts of the stain from the fabric, making stains easier to wash off. As a result, the colours in all 4 stains were lightened, making hydrogen peroxide an effective stain-remover by virtue of its bleaching action, ranking 1^st for tannin stain and 2^nd to baking soda for protein, dye and oil stains, where it was not as effective as it did not chemically dissolve or break up the stains, which baking soda did.

Lemon juice (citric acid) has a low pH of 2-3, while vinegar (acetic acid) is slightly less acidic, with a pH of 2.4-3.4. Although acids denature proteins by destroying their salt bridges, this has to be balanced against their tendency to set protein stains, which makes them tougher to remove compared to bases like baking soda. Their acidity also contributes to their cleaning (bleaching) properties. They function as reducing bleaches, converting the double bonds in dye chromophores into single bonds, thereby abolishing the chromophores’ ability to absorb visible light, rendering them colourless in the process. Reducing bleaches are not as strong in action as oxidising ones, which explains why lemon juice and vinegar were ranked lower than hydrogen peroxide bleach for dye stains. Acids break down oil into component fatty acids and glycerol. Many fatty acids show considerable solubility in water because of the polar carboxyl group, while the three hydrophilic hydroxyl groups in glycerol contribute to its water solubility. Lemon juice was ranked higher than vinegar because it contains lemon oil, which, being non-polar dissolves non-polar oil. Acids dissolve mineral deposits present in coffee and break down glycosidic bonds in tannin molecules to release water-soluble carbohydrates and phenolic acids, hence their efficacy in removing tannin stains. Greater acidity translates to a greater ability to break glycosidic bonds, thus explaining why lemon juice, which is more acidic than vinegar, ranked higher than it. However, both still ranked lower than hydrogen peroxide as its stronger oxidising bleaching actions reduced the tannin stain colour more. Overall, lemon juice ranked higher than vinegar, likely because of its slightly higher acidity and the fact that it has both polar (citric acid) and non-polar (lemon oil) constituents, giving it a wider range of action.

Water is generally known as the universal solvent. Water molecules have marked polarity and tend to form hydrogen bonds with other molecules, hence enabling it to dissolve or dissociate many compounds. Water (control) was the 3^rd best agent for protein stains. Solubility of proteins depends on their configurations and how they are folded. Soluble proteins have their hydrophobic parts in the centre, with hydrophilic amino acid residues on their surfaces. Beef meat juice contains a variable mixture of soluble (myoglobin) and insoluble (globulin) proteins, hence explaining why the stain could be partially removed by water alone. It even outperformed lemon juice and vinegar as their acidity tends to set protein stains, making them harder to remove. Chromophores in dye and oils are non-polar and cannot be dissolved in water, which is polar. Some of their particles are also too dense to be displaced from the material by water molecules alone. Tannins are generally water-soluble, except for some larger condensed tannin molecules which are insoluble, thus explaining why the coffee stains could be partially washed off by water alone.

As in any experiment, there will be limitations. The small sample size here may have led to higher sampling errors, affecting the accuracy of the findings. The 2 dependent variables - stain area and stain colour reductions, were chosen to reflect the efficacy of stain removal. The consistently strong positive Spearman rho correlations between them lend weight to the reliability and validity of the final rankings and hence to the conclusions drawn. Qualitative assessment of stain colour reduction may have compromised accuracy, as the colour chart did not always have an exact matching shade, and the closest hue was settled for. The stains used were combination stains categorised according to their predominant components. For purposes of identifying stain type-specific cleaners, it would have been ideal if pure stains, which are hard to find, had been used. However, in real life, almost all stains are combination types. Due to differences in viscosities of the staining agents, there was a varying degree of stain spreading, resulting in the meat juice and ink stains having relatively smaller areas which inevitably affected accuracy, as a small change in size would result in a disproportionately large percentage change for small stain areas. With the smaller areas, the Spearman rho values were correspondingly lower. Interestingly, the oil stains covered the largest areas and recorded a perfect Spearman rho value of +1.

It was assumed that the temperature of the tap water used for rinsing remained the same for each set. As staining was done at staggered intervals, ambient temperatures were assumed to be similar for all sets during setting.

Conclusions

Of the 4 agents tested, there appears to be no ‘all-in-one’ stain remover which best removes each of the common stain types: protein, dye, oil & tannin. Although the hypothesis is disproved, for practical purposes, the approach is to target specific stains with specific stain removers. The results suggest that for protein, dye and oil stains, baking soda is the best home remedy cleaning agent, while hydrogen peroxide is the best for tannin stains.

Further improvement/future plans

To simulate real-life situations, the stains can be washed with both detergent and water, after pre-soaking in a stain remover. A combination of agents can be tried, for instance, lemon juice and baking soda, to broaden the scope of cleaning action in the quest for an all-in-one stain remover. Higher concentrations of hydrogen peroxide can be tested. A comparison of these agents could be made with commercial ones, and suitable recommendations made in the spirit of environmental conservation. The temperatures for staining can be varied to mimic reality e.g. Coffee should be stained ‘hot’. The timings of setting can be varied to study fresh versus permanent stains. The stains can also be rinsed off at different temperatures, which can affect ease of removal. For more effective cleaning, cloths can be washed with the washing machine using a fixed timing and cycle. Colourimetry can be used for more accurate colour quantification and more sets of data collected to increase statistical significance. Different fabric types and colours can also be tested.

Acknowledgement

Special thanks to Miss Tan Beng Chiak for her patience, invaluable advice & guidance.

References

Breiteneicher, D. & Chapman, L. 2005. A Healthy Environment Starts At Home. Boston.

Chung, S. & Spadini, G. 1983, Nov.1. Bleaching Compositions. US Patent. Internet: http:// www.google.com/patents?hl=en&lr=&vid=USPAT4412934&id=7ZY3AAAAEBAJ&oi=fnd&dq =clothes+stain+removal+with+hydrogen+peroxide&printsec=abstract#v=onepage&q&f=false

Mitchell, J., Carty, D. & Zielske, A. 1988, September 20. Liquid hydrogen peroxide / peracid precursor bleach. United States Patent. Internet: http://www.google.com/patents?hl=en&lr=& vid=USPAT4772290&id=dL0vAAAAEBAJ&oi=fnd&dq=clothes+stain+removal+with+hydrogen+peroxide&printsec=abstract#v=onepage&q&f=false

Taylor, N. 1999. Vinegar: (Almost) the Only Cleaner You’ll Ever Need. The New Homemaker. Internet: http://www.thenewhomemaker.com/vinegar

You, J. & Siklosi, P. 1999, February 16. Stain remover with bleach. United States Patent. Internet: http://www.google.com/patents?hl=en&lr=&vid=USPAT5872090&id=UeIAAAAAEBAJ&oi=fnd&dq=clothes+stain+removal&printsec=abstract#v=onepage&q=clothes%20stain%20removal&f=false