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. 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. After putting it in the warm water, leave it there for 20 minutes before taking it out.
Step 2 - Cutting the Caulk Tube
Cut the tip of of the caulk tube in order to allow yourself to squeeze it out. The most important thing to focus on here is getting the hole the right size. Use a utility knife or scissors to cut the smallest amount possible off of the tip of the caulk tube. Do this at a 45 degree angle. Fasten the caulk tube into your caulk gun, and 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. Do this until the hole is the right size.
Keep in mind that butyl caulk cannot be worked with once it is applied, and that dried caulk shrinks.
Step 3 - Applying the Caulk
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 degree 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 not be able to fix it afterward if you make a mistake. Try to hold the tip steady, but if you must move it towards the surface or away from it, move it away slightly. If you move the caulk gun toward the surface while caulking you may crush, smear or otherwise damage the bead.
Step 4 - Finishing Up
Unlike other types of caulk, you cannot smooth or otherwise fix butyl caulk after you finish working on it. Butyl caulk dries too quickly and is too solid to work on. This is why accuracy is 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.