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How to Make Concrete Coasters in Large Batches

About: A husband & wife team. Amateur makers. Expert high fivers. New video every week (or so). More About evanandkatelyn »

Making a mood ring toilet seat might be the weirdest project we’ve ever done... but it's Reddit's fault (mostly).

Step 1: WHY?

We first started thinking about this project when we saw an image of it on Reddit at the subreddit DiWHY. At first you only might wonder... WHY? Just why would you want to make this?.. but then we started wondering... HOW? What would be the best way to make this? Well, there are some pretty standard ways to turn ANYTHING into a "mood ring" like object. Before we get into that though, some background on how thermochromatic crystals work.

Step 2: HOW?

The liquid crystals we used twist as the temperature changes. At lower temperatures it is non-reflective (black) but as the temperature increases, the light passing through the crystal undergoes Bragg diffraction at the wavelength that has the greatest interference is reflected back, which is perceived as a color by our eyes.

Step 3: Example

Here is an example of a past project undergoing temperature change. In this case we brought this controller from an air-conditioned room into the sunlight which heated up the controller and bent the crystals through their range of colors.

Step 4: Find the Correct Object

Start with a black object (preferably shiny/glossy). The smoother the better. If you spray the thermochromatic liquid crystals over white, the effect is almost nonexistent because the white color will always reflect ALL light, instead of just the light that the crystals are reflecting.

Step 5: Airbrush

Use an airbrush to spray a fine mist of the thermochromatic liquid crystals. We started with the cheapest $9 airbrush we could find... and SEVERELY regretted that. The cheap single action airbrush clogged every 2 minutes or so. We upgraded to a dual action one that cost all of $20!! It was so much better because we were able to open up the nozzle to a larger diameter and it clogged much less and was easier to clean.

Step 6: Protect

The thermochromatic liquid crystals are suspended in what is basically water and NO adhesives/sealers at all. Just rubbing your finger across the coating will rub it off so you need to protect it. In the past we used an enamel spraypaint but that was NOT durable enough. Maybe we did not use enough coats but something like a 2k high gloss clearcoat (basically a spray epoxy) is much more durable. Just spraying a few coats of that on should be good enough but we wanted to play it safe so we went the extra mile.