If you are looking for a sturdy type of caulk that you can paint over once you are done with it, butyl caulk may be just the thing if you don't mind waiting a bit, since it is slow drying enough to coat over. However, this type of caulk can be hard to work with, especially for beginners. What follows should give you the information you need to use it successfully.
Step 1 - Preparing the Caulk
Make sure the caulk is warm enough to use effectively. Cold caulk can harden and become difficult to squeeze out of its tube. Additionally, it can be hard to place accurately once it is out. To keep the caulk warm and easy to work with, soak the tube in warm water before using it. After putting it in the warm water, leave it there for 20 minutes before taking it out.
Step 2 - Cutting the Caulk Tube
Place the caulk tube into your caulking gun. You can then cut the tip of the caulk tube using a utility knife or scissors to cut the tip of the tube at a 45° angle and about the size of the bead you want to apply. You can then try it out on a piece of scrap material. Compare the size of the bead of caulk that you just produced to the crack or gap you plan to fill. If it's too small, make a slightly larger hole to get it the right size.
Step 3 - Applying the Caulk
Before proceeding to apply the sealant, wipe the area clean with a cloth making sure that there is no debris or other residue present around the area. If this is your first time applying caulk, practice the following techniques on scrap material until you are confident that you can replicate them on your actual project. Hold your caulk gun at a 30° angle to the work surface. Squeeze the trigger slowly, moving the tip of the caulk gun along the crack you're trying to seal off. Do this slowly and evenly, as you will find it very difficult to fix your mistakes afterward.
For the best results, you'll need to hold the tip steady while keeping the gun moving in a constant and steady progressive movement in order to make an even bead. If you change the angle of application during the process, you could easily crush, smear or otherwise damage the bead. If you're applying a long bead, you can break it up into shorter sections, but being careful when overlapping because it can get messy and difficult to smooth.
Step 4 - Finishing Up
For smoother results, you will probably need to use a caulking tool (or a plastic spoon). Butyl (as well as silicone and polyurethane caulks) should be tooled or smoothen using a caulking tool or at worst, a plastic spoon. It is not as easy as with water-based caulk that can be tooled with a wet finger. Just make sure to wet your tool with solvent to prevent the caulk from sticking to it, and before starting to tool it, make sure that you have your cleanup supplies ready: a clean rag and solvent.
DO NOT force smoothing the butyl once the surface becomes slightly hard. Butyl caulk dries quickly and this is why accuracy and speed are so important during the previous step.
Wait for 3 days for the caulk to dry. When it's done, you can paint it if you wish.