One thing to ensure when bolting memorials is that holes are clean and dust free. Many memorials are now brought in pre-drilled and generally cleaning involves a blast of compressed air down the hole to blow out any dust.
Unfortunately, if the hole was diamond cored it probably wasn't flushed out and no amount of air will remove the slurry in the bottom and sides. This steel wire brush can be used either wet or dry, after use flush out thoroughly and use compressed air to dry the hole.
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