Black spots in brick mortar

rambling-panda said:

Hey all,

I've just had a garage conversion; A wall was built for the new window. I've started to notice black spots appearing on the mortar surface. When I brush it with my finger it falls out. It's only been about 3 weeks since it was done and I don't want it to get worse.

What is it, is it an issue, and what steps do I need to take to prevent it?

Please see the attached.

Thanks all.

Click to expand...

rambling-panda said:

Why does it crumble away?

Click to expand...

noseall said:

Mortar dye itself is not designed to harden. Pockets of undissolved dye will behave the same as undissolved lumps of sand etc. They will behave how they are supposed to behave - friable.

Click to expand...

rambling-panda said:

Thanks for the information. Can I just fill those holes with new mortar if needs be?

Click to expand...

noseall said:

Yes. Wet it first

Click to expand...