Are you planning to put any detergent or
soap in your bomb? I saw a kid making big
messes with baking soda and vinegar, and I think
she must have had detergent in the mix, to get
such a bubbly mess all over the table cloth.
That's just a thought. I don't have any other
advice, except to try making your bomb in
different ways. For example, what mixture of
baking soda and vinegar works best?