Hi Joah,
This sounds like an interesting project. I do wonder how you plan to measure the outcome for each type of product? That is, how will you measure "removal" of the stain? You probably want to take pictures but you should also have some criteria for measuring removal.
I'm also wondering if it would be feasible to cut the cloth into separate pieces? If you did that, you could put each piece in a separate container to keep the products separate. If you keep them together, it would seem possible for one of the products to seep into one or more of the adjacent sections. If that happened, you would have a hard time determining which product contributed the most to the stain removal.
The suggestion to use a bar of soap also brings up the question whether you are planning to agitate the cloth for each of the products.
Were you going to apply the products to the wet cloth pieces or maybe wait until the cloth pieces had dried?
I know my suggestions are making more work for you, but I would also suggest that you might want to repeat the experiment at least 3 times.
You might find it helpful to browse through the projects in the Science Buddies project database just to see how similar projects handled some of these questions:
https://www.sciencebuddies.org/science- ... e-projects
Be sure to let us know if any of these ideas helped and if you have more questions!