Hi Sean. By 'packing', I believe Tangoman means anything that'll stop the sealant being wasted down the gap - I've heard of rolled-up strips of newspaper being used. A word of caution: getting a good finish with silicone sealant is not a job for the faint-hearted. <u>If you haven't done this kind of job before</u>, then I fear I may be laug.., I mean crying, myself to sleep a few more times from your future posts. (I can see 'Help! How do you remove silicone from walls, worktops, ceilings, the wife...') With such a big gap, I strongly suggest you look around for a <u>finishing strip</u> that'll do the job instead. There are lots to choose from; purpose made for worktops or just wooden beadings, etc.