Results of glow in the dark polymer clay trials

If you use glow in the dark polymer clay, you might be interested in the results of an experiment I started a year ago. At the time I had started to make my own glow in the dark polymer clay by mixing GITD powders with white translucent Premo, as per the instructions on https://thebluebottletree.com/diy-glow-dark-polymer-clay/ from Ginger Davis Allman. To start with I used the powders from Vadien, as mentioned in Ginger’s article but they cost so much to ship to New Zealand that when I had used those up, I ordered more GITD powder from a local company in New Zealand (www.glowinthedark.co.nz), which seemed to work just as well. I now just use green GITD powders as this colour has the strongest and longest lasting glow. 

I was using GITD polymer clay to make products (Swirl-StoNZ by Claire) to sell at craft fairs and, after a customer query, I wanted to see how well it performed and if it was suitable for use outdoor. So I made three lentil bead shapes, approximately 2.5 cm (1 inch) across, with the GITD polymer clay and baked them as per the manufacturer’s instructions. The unmarked one was left on a shelf in my studio (fairly shaded), the one marked ‘S’ was left on a sunny window sill and the one marked ‘W’ was left in a bowl of water (on the desk in my studio, fairly shaded). I left these samples for a whole year and then tested them to see how well they glowed in the dark

Left: shelf  -  Centre: sunny window sill  -  Right: water

My first observation was that they all looked different colours in daylight. It may not show that well in the photograph but most noticeable was the lentil that had been in the water (after drying) was quite white and opaque looking, it had lost its translucency. The lentil bead that had been on the shelf was translucent with a slight brown tinge (even though I had used Premo White Translucent and not regular Translucent). The one that had been on the sunny window sill was translucent with a slight green tinge, almost like it was glowing green but in daylight, I am guessing this was because the photo-luminescent particles in the clay were super charged from being in a sunny position all year.

Photo taken as soon as samples were put in the dark

They say 'a photograph does not lie' but my eyes seemed to see quite differently to this photograph. The centre lentil, which was the one that had been on a sunny window sill, appeared much brighter than the other two that seemed to glow the same.

Photo taken 2 minutes after samples were put in the dark

After two minutes the centre lentil was still glowing much brighter but now the right lentil that had been in the water was not glowing as strongly as the one on the left that had just been on the shelf.

Photo taken 5 minutes after samples were put in the dark

After five minutes the centre lentil was still glowing brighter, the other two were not glowing as strongly but appeared to be similar. 

As I am writing this, I realise that that there are flaws to this experiment. I should have continued to observe the degree of glow for longer than 5 minutes, say again after 10 minutes, half an hour, and hour, etc. Also, would it have been different if the lentil in the water had been placed on the sunny window sill, rather than on my studio desk which is quite shady? 

When I started this trial, I was just curious to see what would happen to the GITD polymer clay that had been immersed in water. I do not think I will bother to repeat or refine this trial but I do feel confident to say that the glow in the dark polymer clay made into a lentil shaped 'stone' should be fine for outdoors. After one whole year totally submerged in water, the polymer clay had not deteriorated and the GITD powders incorporated in the clay still glowed. Exposure to sunlight improves the intensity and length of glow time.