The purpose for the food colouring

Sorry, I had been busy, so hadn't have time to post things (but no excuses). I've finished my experiment, which is of course, a plus, and are well on my way to finish the report, which will certainly take a while.
Thanks Ms Zhang. I see that I did not explain my experiment quite clear. I will attempt to explain it here.
The purpose, of the aim of my experiment is to determine whether the brand of detergent would affect the effectiveness (I think that is how you spell it) of the detergent in removing the grease. The purpose of detergent is so that oily grease may be removed during washing, as water alone is not able to remove the grease.

Within the detergent, there are chains of molecule. However, these molescule have very differnt ends. On one end, there is the water-hating molecule, otherwise known as hydrophobic (lacking affinity for water, repel and not absorb water, tending to not dissolve in, mix with or be wetted by water, hydro-water, phobic-afraid). The other end, there is water-loving components, known as hydrophilic (having a stong affinity for wate, tending to dissolve in, mix in or be wetted by water, kind of like a sponge).

The hydrophobic hydrocarbon are repelled by water, but instead, are attracted to grease and oil, whilst the hydrophilic are attracted to water. So we have chains of these unique molecules in the detergent, with one end attracted to grease and the other attracted to water. This becomes very effective when removing the oil from thing, as the hydrophobic end binds with the grease, and the hydrophilic end becomes attached to the water molecules, thus allowing the detergent, along with the grease, to be pulled away when rinsing.

A little tip for anyone who hates washing: warm or hot water makes removing the grime easier, as it melts the fats and oil, and allow detergent to dissolve and remove the grease easier and faster :)

That is the fundemental explanation for the chemistry of detergent, and how they work in removing grease. As for my experiment, I am testing whether the different brands will affect the effectiveness of the detergent in removing the grease. To test this, I would need to be able to see the process of the removal of grease itself. This is where the food colouring becomes essential to my experiment.

I have brought 4 different brands of detergent, each ranging in prices. There is one of the most expensive brand, one medium expensive, one medium cheap and a cheapest brand. The source of grease will be provided by full cream milk (this is why I would need milk), as there will certainly be quite a lot of fat in full cream milk. If I put a little bit of detergent into the milk, there would bound to be movement, as the hydrophobic end of the molecule is attracted by oil and fat. But is the milk is pure white. how can I observe those movement?

This is where the food colouring comes into play. I thought, the milk is white, why not add colour to it? It's the same theory as movement of water. When people wants to know where a rip is at a beach, they put colouring into the water, and thus obseve the movement of water. So that is the purpose of the food colouring, so that I will be able to clearly observe the movement of the milk, and see which one will react for longer, which one faster.

I hope that this explanation was clearer, and easier to understand.

I will later post my results, the video I took while I was conducting my experiment. I find my result to be very amusing. This experiment was inspired by a thought I had a while ago. The thought was "people spend more money on more expensive things, under the pretense that they are getting a better product, a product that would be more effective. But do they actually work better? Are we actually spending more money for a better product, or are the cheaper product the same as, or in some cases, better, than the more expensive ones."

I was looking forward to what the experiment would show me. So folks, watch out on what you're buying. You may never know that you could spend less money on the same thing with different brand, and it would be more effective.