On Jun 21, 3:45*pm, " wrote:

how are you defining a 'good bond'?

Good bond is when rubbed down very firmly with a wire brush 24hours
later there's no chance of dislodging the patch.

Well there's your problem. 24hrs is way too early to mess with lime,
its strength is close to zero after so little time.



We've been using red brick dust to get the colour (and its pozzolanic
effect) - but the proportion has been 25% (i.e 1 part lime putty, 3
parts sharp sand, 1 part brick dust).

Can anyone tell me more about the possible effects of using such a
large proportion of brick dust?

Its pozzolanic property means it sets quicker and harder, and
breathability is reduced a bit. Dont think it has any other effect.
Just give it much longer before hassling it.


NT