Selleys make a whole range of products that come in a cartridge format. To use a cartridge ensure you have a caulking gun, these can be found in all hardware stores, Selleys have an easy to use gun called the Light Speed Gun.To open the cartridge, use a sharp knife or a pair of secateurs to cut the very tip of the tube you don’t want to cut the threaded part as you need this for the nozzle. You then need to cut the nozzle open, do this at a 45° angle and far enough down so the opening is about 5mm in diameter. It is then a matter of loading the cartridge in to your gun and pulling the trigger to get product out.If it is your first time using a gun then it can help to do a trial spot first to get the feel for how the product works. It is also a good idea to mask up the sides of your join so that you are sure you will get the best possible finish with nice straight edges.