Public Lab Wiki documentation

Oil Testing Kit Construction

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The Public Lab Oil Testing Kit is an attachment to Public Lab's v3.0 Desktop Spectrometer which holds a sample container and a laser.

The Basic Spectrometer

Public Lab first began developing cheap spectrometers in the winter of 2010, after the Deepwater Horizon oil disaster in the Gulf of Mexico. Since then we've made enormous progress and have a variety of designs for less than $100, but the OTK is based around the USB webcam-based Desktop Spectrometry Kit v3.0 (see plans here)

Of course, the plans for all of these are on the Public Lab website and are open source hardware designs, so you can always make your own -- the kits are intended to help you get started.

The Oil Testing Kit attachment

You'll also need a frame to hold your sample container and align a laser beam perpendicular to your spectrometer. For that, we've developed the Beta Oil Testing Kit, an add-on to the Desktop Spectrometer v3.0 pictured here, attached:


If you join the Beta testing program, you can then sign up for the add-on "Beta" Oil Testing Kit (see parts list to assemble your own) in combination with the existing Desktop Spectrometry Kit, which is what was used in the examples on this page.


See this excellent research note for assembly instructions.

Additionally, we've added a light-blocking flap which reduces ambient light. This extra piece (source file here: light-flap.svg) fits into the OTK frame and can be held or taped shut while activating the laser:




Parts list

These are links to where you can buy parts to assemble your own oil testing kit

Sampling materials

Part Est. price Link
acrylic/PMMA cuvettes -- containers for your samples $0.25 each (NOT polystyrene - they melt when filled with lighter petroleum!)
5oz mineral oil (baby oil -- the added fragrance doesn't fluoresce) $3
eyedropper $6 for 100
cotton swabs ~$3 for 500


  • a 405nm blue/violet laser pen: $3 from Alibaba, or for purchasing singles here Some people feel having the caps are useful for dispersing the laser when necessary so if you want more caps perhaps this will be to your liking


Download and cut out all the five pieces on dark, card-stock weight paper such as this:




Light-blocking flap


Alternative parts

We've tried many different bottles and parts; some are no longer available, or had shortcomings. But here's a list of links to things we've tried!