Subject: What is a good substance to form plaque?

I am doing a project on what mouthwash works best on removing plaque from teeth,
but  I'm very confused on the process of how to get the plaque on the teeth.  At
this moment, I am soaking them in coke and then every day brushing them with
water and then shaking them in a container with a specific mouthwash, but I
do not see how that is going to tell me which one removes the plaque.  Is there
a specific way I should be checking for the plaque? Or should I be soaking the
teeth in something else?  If this is not a question that you can answer, can you
please write me back and please tell me so I can get an answer somewhere else. 
Thanks
     Summer

Re: What is a good substance to form plaque?