Thank you

It have been mentioned that it could have been somthing related to peil apparatus, German or norwegian. Earlier there was a hut close by, with isolaters and connection to a peilapparat. (Photo Erik E, kysfort forum https://www.kystfort.com/forum/viewtopi ... dem#p25817)Can someone please identify what this object could be?
I would assume, based on more modern products, that it is a form of bituminous waterproofing paint. This is commonly used on basements and other underground structures to increase moisture resistance. They really aren't "waterproof" however. They would help prevent mold on wood placed on their surface, and keep moisture and humidity down.Elise64 wrote: ↑16 May 2023 09:52Hi all,
I have a question about what seems to be black paint, which appears inside all the blockhaus I have visited that have been walled up. Does anyone know what purpose the black paint serves that is smeared on the interior walls or who put it there? Has anyone else come across this, or is it unique to south-west France? Two examples attached - any help gratefully received.
Elise