Have you ever wondered how some glow in the dark safety signs has a greenish eldritch glow, especially when viewed at night? These glow in the dark fire exit signs are pretty prominent in movie theatres, hotels corridors, offices, shop floors and other areas which are dimly lit. We’re talking about what is known in the print industry as ‘night glow prints’. These glow in the dark prints do not have any light source like LEDs or bulbs. Yet, these fluorescent signs emit light in the absence of electricity.

Glow in the dark prints is widely used to create an emergency glow in the dark safety signs and glow in the dark fire exit signs. In the event of a fire, electrical supply is one of the first things that stop functioning. Visibility is reduced. People trapped in dark, smoke-filled rooms need help finding the nearest exit. And in the absence of power, an electrically-lit sign is of no use. So we need glow in the dark prints which are easily visible and do not need electricity to work.

How Do Night Glow Prints Work?

You may recall the term ‘phosphorescence’ from high school science. Wikipedia describes phosphorescence as a process in which energy is absorbed by a substance and then released slowly in the form of photons of light. Phosphors have this unique quality which makes it emit light when energized. In other words, they absorb and store energy. This pent up energy is then released in the form of visible light. This emission of light happens at a relatively slow rate and continues even in complete darkness. Hence, when viewed in the dark, we experience phosphorescence or light generally seen as a greenish glow.

The thing to remember is that the phosphors need to be first exposed to light. They need to be ‘charged’. This arrangement works perfectly for our glow in the dark signs. The glow printings look like regular signs or posters when viewed in the day or in normal light conditions. They also keep absorbing light during the day. And at nightfall or in times of power failure, the glow in the dark prints emit this absorbed light. The fluorescent signs shine and continue to remain visible in complete darkness.

Production of Night Glow Prints

At Orchid Digitals, Pune, we have a special glow in the dark poster printing vinyl coated with the above mentioned, light-emitting phosphors. We use high-resolution photo printers to render images on these glow in the dark ink printing vinyl and lo behold, you have a glow in the dark sign that shines in absolute darkness.

Glow in the dark media has a light green hue. During the day, the print looks like any regular vinyl sign (except for the light green background). But switch off the light, or let nightfall and you will see a strong green glow emitted from the print.

Our wide-format printing machines produces night glow prints in a large roll form. The prints have an adhesive back and the customer can choose to directly paste the same at the installation site. Alternatively, we can also mount the night glow print on a rigid sheet of plastic. At Orchid Digitals we have a material called sun board (or foam sheet). This sheet is lightweight, flat and rigid. It is generally 3 – 5 mm thick and gives a very finished look to our printed night glow sign.

How Long Does a Glow In The Dark Print Emit Light?

Nightglow prints absorb light during the day (or when exposed to a source of light like a fluorescent tube or an incandescent bulb). This absorbed light is then emitted in darkness. So it stands to reason that the more light a print absorbs, the longer it will glow.

The duration that a glow-in-dark print will keep glowing for, depends on the following three factors…

• The length of time the print is exposed to light: Nightglow prints need to be exposed to light for at least 10 – 15 minutes. This duration gives them time to absorb as much light as they can, which is then leisurely emitted in darkness.

• The strength of the light source the print is exposed: A night glow print cannot be charged by candlelight. To ensure that the print glows for a longer period, make sure that it is exposed to a strong source of light. This will give the print a chance to absorb as much light as it can and glow for a longer duration in the dark.

• Quality of the night glow media: The visibility of a night glow sign depends a lot on the quality of the media used. A low-quality media will glow for only 15 – 20 minutes, in darkness. On the other hand, a high quality branded night glow media should be able to emit light for more than an hour. The print media used at Orchid Digitals is rated to glow for 90 – 120 minutes in the dark. A glow-in-the-dark sign shining for such a long duration should be more than enough to take care of any emergency.

Depending on the factors listed above, these prints will keep radiating light for, anywhere between 45 minutes to a couple of hours. But eventually, the glow emitted by the media  will slowly dim and the print will go dark.

Our glow in the dark ink printing then needs to be ‘charged’ once again. Nightglow prints placed in outdoor locations get automatically charged by the sun during the day. But for indoor locations, the signs need to be placed close to manmade light sources like bulbs and tubes, to recharge the same.

There is one more point that I’d like to mention here. A lot of people confuse night glow prints with night reflective prints. But both these materials are different. Night glow prints emit light absorbed during the day. Night reflective prints on the other hand are made of a specialised material that acts a lot like a mirror. It reflects back any light that falls on its surface, even at night. Reflective prints are ideal for creating road direction boards that are clearly visible even at night, when light from vehicle headlamps fall on them. You can read more about reflective vinyl prints on this page.

Applications of Night Glow Printing Signs

Nightglow prints are primarily used for creating safety signs in buildings, office complexes and factory shop floors. All these areas mandate clear protocols to be followed, in case of emergencies. And these protocols need to be easily communicated if the said emergency does take place. For example, in case of a fire in a hotel, occupants need quick access to two things:

• A map pinpointing their location. This is needed because the guests are in a building that they are not very unfamiliar with.
• Easily visible signs pointing the guests to the nearest exit

Also, in the event of a fire, electrical power supply is generally affected and the occupants are plunged in darkness. Thus night glow media is used to create highly visible fire evacuation maps and emergency exit signs.

Nightglow prints are used in the following use cases:

• Exit signs in generally dark areas (like a theatre)
• Safety signs
• Fire alarm signs
• Emergency exit signs
• Signs highlighting meeting and assembly points during the emergency
• Fire evacuation maps

Apart from their use in safety applications, glow-in-the-dark prints also have novelty value. People print funky and psychedelic looking images on the same. These prints look like regular posters during the day. But in the darkness, they jump out due to their radium glow and garner a lot of attention!

What Is the Cost of Night Glow Prints?

At Orchid Digitals, we provide glow-in-dark prints, in the form of stickers or as rigid signs made of sun board. Given below are costs for the same…

* Please Note:

1. The rates quoted above attract 18% GST
2. The MOQ – Minimum order quantity for this product is 4 feet wide X 2 feet height (since the media is available in rolls having a width of four feet)
3. Rates quoted above are per square foot. So for example, if your image is of size 4 feet width by 2 feet height, and you need a glow-in-dark print in a roll form, the cost for the print job is:

4 feet (width) X 2 feet (height) X ₹ 150 (rate per square foot) = ₹ 1200.00 + 18% GST

Shipping and Delivery

• Night Glow Signs can be delivered anywhere in India.
• Delivery charges are extra and will be communicated to you once we receive the delivery address.