Another major decision is whether to use jointing compound or not. Again lots of different opinions. And of course one very important opinion to take note of is that of your inspector! And mine is keen on jointing compound.
The next decision is which one. There are several choices, but it boils down to JC5A or Duralac. JC5A never quite sets, whereas Duralac does go hard. Some say that setting is not really good, since if it cracks then it will let moisture in and will loose its effectiveness. Others point out that using JC5A is good especially on parts that might need to be disassembled, since it doesn’t set. But then others point out that it’s bad for skin joins, since surplus JC5A seeping out will spoil the paint job!
A quote from LAS Aero about JC5A
This compound is many times the price of Duralac but will not harden with time, thus ensuring better corrosion prevention and easier dismantling of joints.
I’ve decided on JC5A.