[HerpicH (OP)]

Hi, I'm a biomedicine student from Brazil, and I'm doing a project in public schools to bring science to kids. I saw a video about bacteriography and thought it would be very cool to show them something like that. Basically, bacteriography is "drawing with bacteria". It was developed by a guy named Zachary Copfer, and he keeps his process a secret. What I could get from his interviews and from his website is that he basically spreads the bacteria in a uniform layer over a petri dish, covers it with a negative photograph and uses UV light to kill the bacteria under the clear areas of the negative, sparing those under the darker areas, thus creating the drawing.

Of course, the photograph is edited, and there are some details about the making of the art that I don't want to get into. My question is: what kind of material can be used to print the negatives that cover the petri dish? The original pictures are black and white, and the negatives he uses are transparent, with only the black part being visible. I thought it could be acetate sheets, but I'm not sure it can block UV light and protect the bacteria. I wanted to have some clues on what I'm doing before I try it on the lab. Do you have any idea of what kind of material could be used to print the negatives and block the UV light?

There is a video on his website explaining the process, but it seems I can't post the link here. I'm sorry if I'm not being clear, English is not my native language. Thanks for the help

[RD]

... I'm doing a project in public schools to bring science to kids.
 I saw a video about bacteriography and thought it would be very cool to show them something like that.

You can bet the little kiddies will attempt to touch the bacteria.
If your art-work includes something pathogenic there could be an epidemic in the science class.

Black ink on transparent acetate will mask UV. It's used to produce printed-circuit-boards, which are coated in UV-sensitive varnish.  [ Even a photocopy on paper can be used, but the UV exposure time will be longer ].  You'll need to apply a coarse halftone screen the photo.

[ bacteria can generate their own patterns ...
https://microbewiki.kenyon.edu/index.php/Patterns_of_Bacterial_Growth ]

[HerpicH (OP)]

We are using non-pathogenic E. Coli, and the petri dishes will be sealed, so no harm for the kids. We are controlling the bacterial growth by putting it under the UV after 18-24 hours, when it has reached the size we want. I'm trying to draw with loop and swab, and I've got some nice results I'm going to try the transparent acetate next week.