crumbley lime pointing

[loulou71]

I know there is some brilliant advice on procedures / recipes for lime pointing on this forum and others - it's enabled me to do a great job in one room that otherwise I woulnd't have been able to do but now I'm come unstuck. I've not changed the ratio of lime to sand but suddenly ,once it's dry, my pointing work seems to have become more crumbley than my first attempt (running a finger along , a good few days after doing the job produces a shower of sand). I would be very grateful for any ideas.

[Bugsy]

The first question has to be what are you using ?

We used 'Tradifarge' (spelling) at a ratio of half a bag to thirteen full shovels of sand. This was based on a french builders recommendation and works fine.

[shimble]

make sure you are accurately gauging your mix buckets are more accurate than shovels, maybe wet the walls and mix a bit more its hot and dry walls will suck out the water in the mix before it goes off , are you using the same sand

[Chancer]

Make sure that no-one human or especially animal has urinated on the sand or in the mix (plasterers favorite trick on another plasterer).

This is not a joke, I once used some recycled sand from a riding school for block paving, my neighbour also used it for his concrete edgings, my pug wnet off overnight his took several weeks.

[Boris520]

Any chance that a frost got to it, or the sand was frozen prior to mixing ?  Either of these would account for the surface being as you describe.