A simple 4;1 mix with some plasticiser will do the job ... you can add lime
if you have it, but for a small job 4:1 will be good enough.
Apply a coat of diluted PVA first (3 parts PVA to 1 part water) and allow
to become tacky before putting down the mortar.
I wasn't contradicting you. I seem to remember rendering with both and
it all went like soap suds until I stopped using the Feb. "If it goes
pear shaped read the instructions." I just don't remember what it said
on the side of the tin.
It was like working with blancmange and we cobbed two mixes and had
problems with the wall we'd already coated. The penny pinching # we
did it for made us use the stuff up with the rest of the job. All his
walls had tiny cracks in all over. It looked like those tiny mosaic
sheets of tiles.
Don't use plasterziser, its crap. Use 4 to 1 sand/cement with Unibond in
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
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.
highlighted is due to the use of washing up liquid which won't tamp
down. You only use a few ccs -about a large spoonfull of Feb per
bucket of water. Bricklaying mix should be strong enough to suit the
brick and a little softer than the brick -which is controlled by the
ratio of cement to sand.
If you look at the mortar used in old buildings you will see that face
work is very close together. It meant that each brick needed to be
measured for the bonds to work. Modern courses are 1/2" apart allowing
plenty of scope to pull the joints together. Horses for courses. You
couldn't use lime mortar on 1/2" beds could you?
Not the same problems as stone though.
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