Petri Dish Sector Stencils

Repearedly drawing precise lines on Petri dishes for microbiology is important for building consistent experiments with lots of plates, preparing students' plates for labratory classes, and repeatable patterns in photos for image analysis. 

There are three general types of stencils in this collection: 

1. Grid stencils
2. Radial sector stencils
3. Universal sector stencil

Different grid stencils can be used to generate different grids and are easy to use. Draw your lines, rotate the stencil 90° and draw your second set of lines to create the grid (notches are in the stencil to achieve 90°). The 7x RectGrid stencil is a little different as you should use different stencil lanes after turning the stencil 90° (this stencil's use is demonstrated in the photos). 

Radial sectors are very commonly used to separate samples on Petri dishes. These stencils are very easy to use: just draw your lines, and rotate the stencil to draw more sectors if desired.

The universal sector stencil sacrifices a bit of speed while needing fewer radial sector stencils. It can be used to create any radial sector layout in a single stencil. Just draw your first line (half a line for an odd number of sectors), move a dot over your drawn line and draw your next one (still a half line if you desire an odd number of sectors). Dots count up from 3 to 11 sectors. 

Stencils were designed to be used with a standard-tip Sharpie pen, and sized for 85.5mm Fisher brand plates.