Antifreeze leak on header flange

I have in the past used RV sealant and worked, same sealant I used for the water pump/ timing cover bolts. I started using Teflon tape on the exhaust bolts with good results. I have found it easier to remove the bolts/studs using the tape. I think there is a trick in using the tape, I wrap the bolt making sure the tape tightens when bolt goes in. And I increase the number of wraps as you get closer to the head of the bolt.

The RV works great, but the threads must be absolutely clean and dry, no residue antifreeze left overs. Carb cleaner and air gun works if I can get to area it needs to be. They do make a liquid form of the Teflon tape, I have never used it.