Science Buddies: "Ask an Expert"

My son would like to do a project on which Detergent works best. How can we analyze the results based on the pH scale of the products?

You could test the pH of the different detergents using pH strips.
To determine how clean the clothing is, you could use pieces of the same white clothe material and a black permanent marker.
You could mark up stripes of increasing intensity along each piece of clothe (keeping the marker and the various sizes the same). and then you would put the clothe in the washer with the different detergents and see which strengths of intensity each detergent is able to remove?
I'm not sure if this would actually work- but it's an idea.
Hope this helps.