Hello Supersteve & nice to have you as member of Pherotalk 
Hmm, i have never heard of Contact 18 but it work well for you at some time & then it did not work for you. Interesting product to me
Anyway the best effective products that i can recommend on my part is AMMO as it is all rounder sex pheromone & is buffered & go with socials pheros such as Instant shine, Instant Openness or Instant Honesty for best results. For more detailed info on the pheros here, click on the link> Mens Pheromone Guide revised 6/15
I hope you will enjoyed yourself in this forum & wish you all the best if you decide to buy the pheros here. See you