Lime mortar on K rend

[waggonway]

Hi, I have recently had the pointing on a sandstone wall done. Unfortunately some of the mortar has marked a nearby new wall which is rendered with K rend. Can I use brick acid to clean it?

thanks

 

[JohnD]

lime mortar is a bit soft and slow to harden. Have you tried a stiff brush and hosepipe?

 

[waggonway]

Hi John,
Thanks for your reply. Yes I have a go with a brush and water, even escalated to a power washer. It is a few marks, notably a handprint and they have set hard. I agree totally that is should be soft but it is just not moving.