Kitchen Towel works for us too!!
I use the "Customers" kitchen towel.....so they understand that there are no tricks involved. I have two needle craft type hoops. 1 sheet of towel in each hoop. One is left dry, the other sprayed with protector. Couple of minutes with the hair dryer.....then when dry, put drops of coffee, juice or whatever.....well you all know the results there.
Amazes the clients every time....especially as using their kitchen towel.
Kind Regards
Tim