I think this has been discussed on the forum before, but I'm not getting any hits in the search. It does help to spell it "cobweb." Google provides the
commercial products to do the job if you don't find the proportions for your formula.
Here is a link to the
Dr. T's material safety data sheet pdf that lists only Sodium Lauryl Sulfate and Coriander Oil as ingredients. Sodium Lauryl Sulfate is a coconut product, used in shampoos and soaps as a foaming agent or perhaps to hold ingredients in suspension. I imagine you could add some coriander oil to shampoo, dilute with water to spray and give it a test in an inconspicuous place.
The MSDS also has contact information that you could utilize to get answers.