[Cob] cleaning lime plaster walls?

[Tys Sniffen]

So, my lime washed earthen plaster walls (and built in furniture) are
starting to look like they need some cleaning.  Anyone have any experience
cleaning a lime washed wall without rubbing off the white?  

 

I usually use vinegar in all my cleaning projects, but it seems to be a bit
harsh on the wall, and doesn't seem to pull off the dirt the way I would
like. 

 

I did some searching online, but only found this:
http://www.ehow.com/how_8021221_way-clean-plaster-walls.html and wondered if
there was any other ideas.

 

Cheers,

Tys