Brad, who works in the trade of caullking high rise buildings, sent in the tip of dipping a shaped piece of wood into Sunlight detergent before tooling the caulking. This gives the caulking the exact shape you want, but nothing sticks to the wooden tool.
Then we looked at a gadget that is available in most hardware stores. It is simply a split guide that goes on the end of the caulking gun. This will straddle boards such floor joists and guide the caulking or adhesive in a nice straight line down the centre of the board. Guiding Tip from CG Tips.