I was trained to "induce a biologic patina" by the application of cow manure
soaked in a barrel of water for about ten days, with the liquid reserved and
sprayed on the wall surface.  It was not a terribly popular process,
particularly in respect of assembling the raw materials, but it worked great . .
. and bullshit is definitely cheaper than potatoes.

Lisa


>I usually suggest rubbing raw potatoes on masonry in order to induce a
>biologic patina that turns black within a few months. Can't say how well >it
works as I'm still waiting on a customer to hire us to rub potatoes on >their
walls. My GRAND IDEA is to make potatoe juice and use a modified >Hudson sprayer
for application.

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