any good waterproof materials?

[dudesky]

Hello brothers sisters and friends
I currently having a water leaking problem in my trunk, due to poor spoiler installation. (damn me, stupid myself) As you know, it is pretty damn cold outside and because I bit rushed through the procedure, water leaks! I am planning to redo the installation tonight and if anyone had similar problem, any recommendation would be helpful! I am currently looking at to buy either "Rubber Foam Tape" or "Silicone washers" and put them inbetween the holes and where the machine screws contact with the spoiler brackets. I have no idea how that foam tape is waterproof? Wouldn't water gets soaked into the foam?? I used silicone sealant before but it still leaks. I guess the sealant didn't dry at all due to the cold temperature. What materials should I put inbetween the brackets and the trunk metal?