Don't use plasterziser, its crap. Use 4 to 1 sand/cement with Unibond in
the
water, use the same water and paint both coping and receiving bed of
brickwork prior to spreading mortar.
Sand and Lime were use for century in the building trade. When cement
mortars came used, it was found that this type of mortar was heavy and
didn't
spread very well. So they introduced plasterzier in to the water. This
plasterziser put bubbles in the mortar when mixed. When the bricks are
pressed down the bubbles collapse making it easier to level the material
being laid. The problem arises when the weather starts to ware away the
mortar, its full of dried empty bubbles.
In a recent article in one of the construction mags, There are proposals of
going back to Lime mortar for brickwork. One of the theories behind the
use of Lime mortar is that in the case of any movement in brickwork the
joint gives, in cement mortar the bricks give and snap.



John wrote in message
...
I have some coping stones to rebed on a low wall (18" high) in our back
garden. The wall was already there when we moved in, so I know nothing
of it's history. The copings are approx 3 ft by 1 ft and just look like
the concrete paving slabs around my garden. As these stones are all
loose and have come unstuck from the original bed of mortar, which is
still on the bricks below, but I will chip it off with a 4" bolster.
What do I do with the mortar mix to make sure they stick!

Thanks

John