white marks after re-pointing

[jimbob2008]

Finally got round to doing some re-pointing on my house. I've noticed that when the mortar starts to dry, the brickwork around the gaps goes white. Is this salt?? Will it wash off over time? Is there something I can be doing to prevent it/make it easier to remove??

Cheers

 

[Joe Malone]

sounds like salt efflorescense. Presumably you used a clean potable water source for the mortar?

Also hope you didn't use washing up liquid as a plasticiser, it contains salt as a bulking agent.

Chances are the salt is already in the existing masonry in which case just wait for it to dry and brush it off with a stiff brush, not much else you can do unfortunately.

 

[jimbob2008]

erm, i used water from the outside tap.

I did not use washing up liquid. Used a ratio of 4 builders sand to 1 snowcrete so as to get a good match to the existing mortar.

i will try brushing it off, just hope it doesnt brush off any of the pointing

is salt efflorcense a common thing then

 

[Joe Malone]

Not as much as it used to be, a lot of aggregates and even sand weren't washed with clean water and contained salt from the sea which meant we already had it in the building materials ready to crystallise out as efflorescence.
If you know the materials and water were clean then it's already in the masonry. More an aesthetic problem but the salts will blocks the pores of the masonry and slow the drying process, if they're hygroscopic they'll even draw moisture into the brickwork from the atmosphere.