If At First You Don't Succeed...Try 6 More Times

I'm pretty sure that's the aphorism in its original form, right? Well, it definitely describes my luminophores journey. Last week I received both types of pigments in the mail to start testing on the sediment grains, and this week I tried, and tried, and tried to get things to work. While luminophores are a known tool in the field of particle tracing, there are patents surrounding the dyeing techniques, which makes it hard for me to create my own versions. However, I thought creating luminophores would be similar to dyeing clothing: 1) dissolve the pigment in a liquid, 2) soak the material to be dyed, 3) wash off excess dye. The difference between cotton and sediment, however, is one of the major challenges, which is that sediments aren't porous. Additionally, there's not a great binding agent (that I know of) to use to get pigments to stick to sediments, like how we use soda ash or other salts to dye clothing.

The first test, shown here, was with saltwater as the liquid. And while you can see that there is luminescence in this image, the glow comes from pigment powder that was undissolved and left as residue. In addition to saltwater, I tried tap water, lime juice, ethanol, acetone, food coloring, and vinegar. While some of these solvents worked better than saltwater, none of them dissolved the pigments well and none of them stained the sediments. Again, this is likely because of the lack of binding agent in this process. Currently, I have three more options to try, though they are all less natural solutions than I'd have liked. My next step is dissolving riboflavin in food coloring and then trying to stain particles with this mixture. Food coloring itself can dye sand--or at least so I've read--and riboflavin is a food safe substance that fluoresces under UV light. Additionally, I am going to try glow in the dark or fluorescent paint to paint the sediment grains in a somewhat tedious process and ammonia as a final option. 

If none of these solutions work, I do have a backup, though it will get quite expensive. The company I get my microplastics from also sells glass microbeads that are coated with fluorescent dye. These glass microbeads are sold in small quantities and are expensive considering I need enough for a test experiment and the real experiment. Fear not, I will get this to work, and I think this is just another step in the learning process leading to graduation.

There will not be a post next week as I will be gone all week, but stay tuned for an update on this luminophore process.

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