What are glow granules, glow stones and glow jelly?
Glow granules, glow stones and glow jelly contain a glow pigment that stores light and releases it again in the dark – without electricity and as often as you like. They differ mainly in shape and size: from fine grains for stirring in, to broken decorative stones, to a mix that swells into a gel with water.
The granules and stones are based on strontium aluminate, today the common material for long afterglow. In the granules it is doped with europium and dysprosium. In the 4 mm granules, the pigment is also bound in synthetic resin.
Which product suits your project?
The choice depends on whether the glow is to be worked in, scattered loose or placed in a jar.
| Product | Size and contents | Typical use | Water |
|---|---|---|---|
| Glow granules 1 mm | approx. 0.5–1 mm, 100 g | stirring into casting resin, varnish or glue; sprinkling | not waterproof |
| Glow granules 4 mm | 4–8 mm, 100 g | loose as decoration, in surfaces of resin, paint or concrete | resistant to water |
| Glow stones | pieces of approx. 2 cm each, 300 g | beds, pots, path edges; in resin, concrete or terrazzo | for indoors and outdoors |
| Glow jelly | 50 g for approx. 1 litre of gel | bottles and jars as an orientation light | mixed with tap water |
You will find detailed guides to each group under glow granules, glow stones and glow jelly.
How long do granules, stones and jelly glow?
The afterglow duration depends mainly on the colour: green, blue-green and untinted blue glow longest, tinted shades for a shorter time. All values apply after a full charge, in complete darkness.
| Product | Colours | Afterglow duration |
|---|---|---|
| Glow granules 1 mm and 4 mm | Green, Blue, Blue-Green | up to 12 hours |
| Glow granules 1 mm | Yellow, Orange | up to 4 hours |
| Glow granules 1 mm | Orange-Red, Pink | up to 2 hours |
| Glow stones | Green, Blue-Green | usually more than 8 hours |
| Glow stones | Yellow | up to 4 hours |
| Glow stones | Brown | up to 2 hours, only faint |
| Glow stones | Blue | approx. 1 hour |
| Glow jelly | all variants | several hours |
The glow is at its strongest in the first few minutes. After 1–2 hours it turns into a soft glimmer that eyes used to the dark can still see for a long time.
How do you charge granules, stones and jelly?
All three charge with any light source, as often as you like. For the glow granules, these are guide values for a full charge:
| Light source | Time |
|---|---|
| UV light from 365 nm | 2–4 minutes |
| Sun | 6–9 minutes |
| Fluorescent lamp | 20–24 minutes |
| Incandescent bulb | approx. 25 minutes |
Glow stones need only a few seconds to minutes of light; UV light is fastest. Place the glow jelly in daylight or under a lamp.
What can granules and stones withstand?
The products cope with water, heat and weather to different degrees – check this before you buy.
- Water: the 1 mm glow granules are not waterproof. In water they dissolve over time and the glow effect is lost. For water, use the 4 mm granules or embed the fine grains in resin or a water-resistant clear varnish.
- Heat: untinted 1 mm granules are heat-resistant up to 1,200 °C; do not heat tinted ones above approx. 150 °C. The 4 mm granules can be processed up to approx. 300 °C.
- Outdoors: glow stones are suitable for indoors and outdoors. Outdoors, work granules into solvent-based, weather-resistant carriers such as epoxy or exterior clear varnish. Choose a spot that gets light during the day.
- Concrete: mixed into the compound, grains and stones disappear. Press them into the still-wet surface and sand flush after curing.
Good to know
Afterglow is an aid for orientation and effects, not a light source. It becomes visible in real darkness, but barely under a streetlight. Granules worked into a carrier glow more strongly the clearer and lighter the carrier is. Granules and stones are materials, not toys. Glow jelly is not edible and not for children under 5.
Related products and background
For very fine effects in paint, varnish or resin, there is glow powder. Epoxy casting resin is suitable for embedding granules and stones. You can read how charging and fading work under Afterglow explained.