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How do things Glow-in-the-Dark?

Back in the day when kids got a packet of glow stickers or glow plastic stars, they would put them up eagerly awaiting nightfall, only to be utterly disappointed by how short-lived and how weakly they glowed. Even when fully charged with light they would last all but a few minutes before fading into darkness. Of course, glow technology has come a long way over the last decade or two and we now have strontium-aluminate based paint and stickers which can glow for over 14 hours and last 10 years or more. However, the expectation of a constant 'bright glow' that lasts all night long is still alas, unrealistic even with today's technology. 


So how does Glow-in-the-Dark actually work?

Every glow product be it a glow star, glow sticker, glow sign or a pot of glow paint etc, is made using glow powder; thousands of microscopic crystals suspended in a clear medium be it a liquid (for paint) or a plastic compound or vinyl sheet. Each of these tiny crystals absorbs invisible ultraviolet energy (it's charge) from any natural or artificial light source and instantly converts it to visible light (it’s glow) and in doing so retains some of the UV energy for use later. As this conversion process happens in real-time the ‘greeny’ appearance (hue) of the glow product in daylight is in fact the result of the green glow being emitted by the crystals.

When the light source is suddenly removed (or turned off!) the retained energy continues to be converted to visible light (it’s glow) but only for a relatively short period (minutes), during which time the glow produced will still be relatively bright. However, when the retained energy falls below a given level, the crystals start to conserve and ration the remaining energy in the form of a much dimmer green glow; released over an extended period (known as the afterglow phase and can last several hours) which gradually becomes dimmer over time and only really visible in complete darkness.

Glow powders now come in different glow colours i.e. green, aqua, blue, orange white, purple and red. Each glow colour has a different set of performance dynamics in terms of its glow colour, intensity and duration. Green for example is the core glow engine of every coloured glow product, it is the brightest and longest glowing of all glow colours and underpins all the other glow colours. Correspondingly red is the weakest and the shortest lived.

Imagine if you will, a set of balancing scales (with ‘glow colour’ as the left scale and ‘glow performance’ as the right).  When in the balanced state they represent green; at the top of the glow performance table. If we wanted to create an aqua-blue glow colour, we add weight on the left in favour of colour which results in a corresponding reduction in performance on the right.


Starglow Paint relative glow performance graph


Moving down the colour chart from green to red, this shift in favour of colour generation at the expense of performance, becomes more apparent in the corresponding decrease in glow intensity and duration achieved as we descend the colour scale.


The scientific version

Phosphorescent or Photo luminescent are Luminescent Pigments, or powders that can give off light.   

Unlike conventional colorants, LUMINESCENT pigments are not primary light reflectors, but actual sources of light. They possess the property of absorbing certain types of radiant energy (usually below 4000A and not visible to the eye) and converting this radiant energy into longer wavelengths in the visible spectrum, and emitting it as light. The selective wavelengths, thus emitted, produce the sensation of 'colours'.

When the emission of luminescent light ceases with the removal of the charging light source, the luminescent material is called FLUORESCENT. If the emission of light continues for an appreciable period of time after the exciting energy has been removed, the luminescent material is known as PHOSPHORESCENT or PHOTO-LUMINESCENT, and has the property of glowing-in-the-dark.".

The ability to absorb light, and then release this light in a decay pattern is known as PERSISTENCE or AFTERGLOW. Different types of phosphorescent pigments emit light in different decay patterns. The unit of measurement for persistence is MILLICANDELA per square meter or mcd/m2.

Some emit fairly high amounts of light initially, and then continue to emit diminishing light levels for 5-8 hours with some able to emit light for more than 14 hours, even up to 20 hours, although even with the strongest of afterglows, after a few hours it is often too difficult (or practical) to see with the human eye.



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Can I use daylight charge-up glow paint?

Yes it can but please do not rely on it for use during the hours of darkness! 

It does not really matter how many hours of daylight the paint is exposed to (indoors or outdoors) as during the time it takes  daylight  to become the dark of night (usually around 3 hours) most of the stored energy has been burned-off in glowing whilst it is still too light to see it!  The reason is simply that Glow Paint (and other glow products) are actually glowing all the time and they do not save-up all their energy waiting for it to become dark. For this reason we do not recommend using STARGLOW Luminous Paints outdoors.

We recommend at least one UV Blacklight unit in the room and turned on a good 20-30 minutes before bedtime in order to 'charge-up' the glow paint / stars etc so they will glow brightly and look their best when it matters most.

STARGLOW Clear UV Paints are not suitable for outdoor use or exposure to direct sunlight


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Will I need to use a UV Blacklight with Glow Paint?

Whilst daylight (natural light) will charge this paint,  by the time the dark of night has arrived it will only result in a weak glow, as most of the energy stored will already have been used. If the room has suitable electric lighting, then this should be adequate to charge the ceiling for 20 - 30 minutes or so before bedtime. However For the best effect and glow performance, we recommend using a mains UV Blacklight.


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Do all glow colours glow for the same length of time?

No. Each colour of glow paint / powder is different to the next in terms of its glow duration and glow intensity (brightness).  Green is the brightest by far and all glow colours are based on a 'green glow' engine, however by changing the glow colour away from green you have to sacrifice glow duration and brightness in order to achieve it.  The graphic below shows the dramatic drop-off in performance the further away from green you go...



Starglow Paint relative glow performance graph

This chart relates to Glow-in-the-Dark paint only. Not UN Neon nor Invisible UV Revealing paint



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Are your products really as safe as you claim?

Yes of course. Remember, this is next-generation, all-new technology, it is not the radioactive stuff used on watches decades ago or the old-fashioned Zinc-Sulfide stuff that only glows for a few minutes. This is Strontium-Aluminate based technology which is not only completely safe, it can last 10 times longer and glow 10 times brighter.


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Why do some colours cost more than others?

The most natural (and least expensive) colour to produce for glow-in-the-dark is a light green, which is also the most receptive to the eye. Aqua and Sky-Blue are also relatively straight forward to produce.

However the hardest (and significantly more costly) colours to produce are Red, Orange and White. Whilst orange and white are still able to offer reasonable afterglow performances, red only lasts 10-15 minutes which makes it the most expensive with the lowest afterglow. 

See our relative colour performance chart above.


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How do I use STARGLOW Glow Powder?

STARGLOW Glow Powder can been safely used in a multitude of clear or opaque spirit and water-based mediums, however it is important you test the compatibility of powder and medium before using both together. We recommend you order a sample of the glow powder first to allow you to do this. 

Glow powder is in fact a microscopic crystal which is usually suspended in a clear medium. The weight (specific gravity) of these crystals is quite high so they will naturally settle due to the effects of gravity.

Click here for more information.


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How do I use STARGLOW Paint?

STARGLOW Paint is a safe (non-toxic) water based acrylic paint which can safely be used indoors and out.

NB: We do not recommend using glow paints outdoors. However if you choose to use Glow-in-the-Dark Paint outdoors, ensure the area is totally dark at night and not lit by any form of lighting, including street-lighting. 10 year Guarantee does not apply to STARGLOW Paints used externally.

STARGLOW Invisible UV Paints are not suitable for pro-longed outdoor use or exposure to direct sunlight.

Click here for more information.


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What area will a pot of STARGLOW paint cover?

This rather depends on factors such as surface type, texture and porosity, the method of application, how liberally it is applied and even temperature.  As a rough guide we generally say that a 30ml pot will cover an area the size of an A4 piece of paper, up to 8 square meters per litre. We believe this is more of a conservative estimate.


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How long will your glow paints and powders keep glowing for?

This is new technology developed over the last few years. However, based on laboratory tests, the boffins estimate  our glow paints and powders should enjoy an active lifespan of around 20 years, with a guaranteed active life of 10 years.


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Are you able to supply business customers as well?

As a business we mainly supply to other business customers from small Craft Shops and Artists to large companies around the world.


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Do you have a minimum order quantity?

For web based customers we accept all orders whatever their size.  For smaller quantities and samples.


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Do you supply other retailers or shops with STARGLOW Products?

GLOWTEC manufacture and mainly supply exclusively through our online store. We do not supply our products through third party retail outlets, except where we have a special arrangement.


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Do you ship just to the UK?

We ship worldwide (see our shipping policy).


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Do you offer any guarantees for your products?

Absolutely. We are really very proud of all our products and confidently back them up with our 10  Year Guarantee Click here for details.


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What is Strontium-Aluminate?

There are two types of Glow-in-the-Dark (GITD) technology in use today, one is Zinc Sulfide and the other newer form is Strontium Aluminate with Europium as an activator. This powder (or crystal) is a non-radioactive phosphorescent pigment produced from rare-earth elements and provides an extreme long-lived afterglow. This afterglow last about 10 times longer than conventional (Zinc Sulfide) pigments and is about 10 times brighter.


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What is Rare-Earth?

see 'What is Strontium-Aluminate'

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What is Zinc Sulfide?

Prior to the development of Strontium-Aluminate based Glow-in-the-Dark (GITD) pigments, most GITD products including children's toys and stick-up stars etc were manufacture using Zinc-Sulfide.

Zinc-Sulfide whilst relatively inexpensive, only provided a poor afterglow which did not last longer than a few minutes.


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What is Black Light and is it dangerous?

Have you ever been to a disco / party where the DJ used a long purple fluorescent tube that made anything white shine in the dark?  That was Black-Light i.e. an Ultra-Violet light). 

Black-lights 'shine' Ultra-Violet light of which there are three kinds;  A, B and C.  The two most often referred to are B and C.  These are the potentially harmful forms of UV, against which you should protect yourself when sunbathing etc.   However it is UV 'A' that is emitted by a black light bulb and in this form it is completely harmless.  Click here for a simple guide to UV and Blacklight.


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How good is REFLECTIVE Paint?

Almost impossible to answer this question with absolute certainty as every situation is different from the next and every customer has different expectations and needs. 

The principles involved are relatively simple and if the conditions are right, then the effect is great.  However, if the circumstances or conditions are not right e.g.. the distance from the light source is too short or relative direction / viewing angle are too wide etc etc, then the retro-reflective effect will be negligible. 

The only way to know for sure is to try it and see.  To this end we do have small 30ml trial-size sample pots available to buy on this web site.

Please note:  Due to the simple nature of this coating, it can never equal the performance of  manufactured reflective materials, such as those used on safety jackets and metallised multi-layered reflective traffic signs, but its still good, and as close as you can get in liquid form! (particularly Ultra Reflective).

Reflective coatings work best when reflecting from a distance rather than close up. In much the same way as a distant road sign reflects when driving towards it at night.

Under normal light conditions the coating should be clear and unobtrusive, so to see the reflective effect yourself, try holding a torch (flashlight) up at eye-level and point it directly at the painted surface or take a flash-photo and see the reflection in the photo.  The end-result will depend on light / flash strength and distance, but you'll get the idea.


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Do you provide free samples?

Much as we would love to do so, we regret that we cannot. We get so many requests for samples of our products, that to supply them free-of-charge is not possible.

We do have samples of all paint and powder products available to buy-and-try on this website.


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