In summary, can frost proofer which is *not* suitable for lime mortar be
used safely in a 6:1:1 mix?

The background is that I need to do a little bit of repointing to a
chimney this weekend despite the current cold weather. It's a Victorian
house with soft bricks and movement so I was planning on a 6:1:1 mix.
And with the cold weather also adding a frost proofer. But the ones I
have found locally (eg at Wickes) say they are not for use with lime
mortars(see eg
http://www.wickes.co.uk/content/ebiz...es/gil/12.pdf).
I don't know if a 6:1:1 mix counts as a lime mortar for this purpose.
Nor do I know what else I might use (and be able to get hold of on a
Saturday afternoon or Sunday morning).

--
Robin