I sent along the photos to Jamie, our resident archaeologist, and this is what he had to say.
It seems like an investigation as prelude to the restoration of the building. It's protected as a Denkmal, which means when it is restored it needs to maintain its historical appearance. The types of mortar and paint used in the restoration are required to conform to the original mortar and paint. This looks like an investigation to establish which paint and mortar are the earliest ones used. They have exposed different paint layers that have built up over time in order to see which one was the first. Alternatively they might be aiming to restore the structure to the appearance it had at a particular point in time (eg 1920s).
Once restored, it might look like a similar building just down the road: http://www.perlon-labor.
From this photo I was able to do some research about the former factory, and it seems it was producing chemicals used in the dying of fabrics.