Choosing the right medium for glow in the dark powders
Not all glow in the dark powders are the same.
Not all glow in the dark powders work with all mediums. It’s important to know what mediums are compatible with your glow in the dark powder to avoid a costly mistake.
Glow in the dark powders basically come in two forms: coated and uncoated. Why is this important?
Glow in the dark powders are actually tiny crystals. If you’ve ever made crystals with those toy chemistry sets you’ll understand that they are soluble in water. Uncoated glow in the dark powders are just the same. If they are exposed to water they will start to break down until they lose all their ability to glow in the dark.
So if you want to work with a water based medium such as acrylic paint or gel then you must use coated powders. If you plan on using a solvent or oil based medium then either type of powder can be used.
So how do you know if your powders are coated or not? Basically you don’t. You have to trust the retailer where you bought the powder. The largest grain powders 55-80um and larger often flow like sand when coated but to the untrained eye it’s a crap-shoot. At Kosmic Kreations all of our glow in the dark powders except for the zinc red, which we are phasing out, are coated.
Solvent or Acrylic for paint?
When I started out painting star murals years ago I purchased a quart of solvent paint from a very good company. By the time I finished the first room I was so excited I never noticed how intoxicated I had become. Even though I had left a window open there was no way my kid would be sleeping in that room tonight.
When I painted my second room I was wearing a full active carbon respirator. I finished that room easily and without almost passing out. However, when I finally removed the mask the fumes in the room were so high I swear that a lit match would have blown me to the stars I was painting.
My point here is that there is absolutely no reason why you should ever consider using a solvent medium or pre mixed solvent glow in the dark paints. It’s just stupid. So save yourself all the problems and stick with acrylic mediums.
Can I mix with a colored medium?
I get this question asked a lot. On paper it seems like a good idea but in practice for most applications it’s not a good idea. Here’s the problem: Glow in the dark paints work by storing light energy and emitting it back out at a different wave length. For this to work the glow in the dark powder must be able to be charged by the light and able to emit it back. A colored medium will coat the glow in the dark powder and severely restrict its ability to charge and emit.
So in a nutshell it will work because there will be some glow in the dark crystals that get charged and will be able to emit. But the majority will just go to waste. However, the glow will not be very bright and it will fade very quickly.
So what’s the best medium for paint?
The best medium for paint is a clear gloss acrylic gel. I use gel from Golden Paints but Liquitex or other brands should work well. Just like with a colored medium a matte medium is also not recommended due to the frosted finish that will also limit the glow in the dark paint’s ability to charge and emit.
To UV or not to UV? What was that question?
UV light is by far the best charging source there is. Eliminating or limiting the amount of UV light that can get to the glow in the dark powder is going to potentially reduce the effectiveness of the paint. However, my testing has shown that the Golden gel even though it contains UVLS stabilizers there is no effect on the glow in the dark powder’s ability to charge or the duration of glow.
The other downside to not using a UVLS stabilizer is that over time the medium with go a yellow-brown. Not a nice thought if you paint a mural over a white ceiling. Or if you use resin to cast an object.
I have heard from people who claim that their glow in the dark powder simply will not charge at all when mixed with their UV protected medium. I can’t tell if it’s their powder or medium at fault. I know that for the past four years I have not had a single problem using Golden’s acrylic gel with UVLS stabilizers.
OK so I can’t mix with color. What about painting over colored surfaces?
Regular colored paint works by absorbing light in a particular wavelength and reflecting the remainder. Your eyes absorb the reflected wavelength and your brain perceives color. Glow in the dark paint works very differently. The glow in the dark crystals absorb light at one wavelength and emit the light in another. That light is emitted in all directions. The more light that is reflected towards the viewer the better.
So white is the best background color because it will reflect the most light back towards the viewer. Naturally black will be the worst color.
One other thing to note is that no glow in the dark paint is invisible. Anyone that claims so is not telling the whole truth. If it were invisible then the glow in the dark powders that I use would also have to be invisible and that would make working with them rather hard. :) Glow in the dark powders are an off-white. So it goes without saying that if I mix glow in the dark powder into a clear medium that the paint will have an off-white color. If only it were that simple... The medium is often white when liquid and clear only when dry. This might give the impression that the glow in the dark paint will dry clear but in reality after the paint dries you’ll be able to see the off-white glow in the dark powder suspended in the dry medium.
I’ve spent a lot of time on this subject and have more to say about this in my guide. Just click on this line to take you to the topic. Painting on colored surfaces.
What about using epoxy or resin?
A lot of work has been done on this topic. Some are better that others and you certainly want to use one with UV filters. If you’re interested in this topic then go read the thread’s in the Kosmic Forum where there is much more information.