How Do You Find Phosphor On Stamps?

Phosphor was included on stamps in Great Britain starting in the late 1950s and early 1960s. It was implemented using colored phosphor bands and the purpose was to help with automating the British postal system. This has led many collectors to wonder how they can find phosphor on their stamps.

Finding phosphor on stamps is accomplished by knowing where the phosphor indicator is placed and how it was added to the stamp. Once you know how the colored system works and the measurements of the bands on a stamp, finding the phosphor can be done with the naked eye or with specialized equipment.

The key to finding phosphor indicators on any stamps is knowing where they are placed and what type of phosphor marker was used. The colors, placement and type depend largely on the country marking the stamps. Below, we’ll go into more detail about finding phosphor on stamps, and why it was used.

Phosphor And Why It Was Used On Stamps

Postage stamps revolutionized how the public communicated. Stamps and a new way to compute delivery costs made it possible for just about everyone to send a parcel through the mail without making huge financial sacrifices. Suddenly, mail was not a luxury, but an affordable option.

Prior To Postage Stamps

Before stamps, delivering parcels was something only the wealthy could afford. Delivery costs were calculated by multiplying the number of sheets mailed and the number of miles the parcel traveled by separate rates and then adding them together. Often, different cities had different mileage rates and charges per sheet.

Additionally, postage was also due upon delivery, which put the burden of the cost on the receiver of mail, whether they wanted to receive the mail or not. Politicians were also exempted from paying postage, which offended just about everyone involved.

For the average person, mailing one standard letter across England cost about an entire day’s wages. For people struggling to put food on the table, mail was simply not in the budget. For unanticipated mail, the burden of paying for a parcel was an unforeseen expense, which, when margins were razor thin, could cause financial hardship.

Stamps And New Ways Of Paying For Postage

In 1841, the first Penny Black Stamp was introduced. Rates were pre-determined, based on a flat rate and the weight of the parcel and pre-paid. This alleviated the burden of receiving unsolicited mail.

Additionally, because postage costs were spread across all parcels, rates to send mail dropped significantly. Rates dropped so much the average person could afford to send mail. That opened new avenues for people to communicate.

Postal Growth

The stamp system was instantly popular. Very quickly, most developed nations implemented a stamp and postal system that was very similar to Great Britain’s. As word of the new system got out, more and more people started utilizing the postal system.

That led to the need to sort mail and verify postage beyond what an average person could do by hand. The necessity led to automation technology. It was, however, extremely laborious for postal officials to sort and verify postage for every parcel.

The answer was to use phosphor to mark stamps to indicate their overall value, which helped make sorting mail easier. It was implemented in Great Britain in the late 1950s and was quickly adopted by countries across the globe.

Phosphor Stamps Today

Today, several countries still use phosphor, including the United States, Canada and Great Britain. The term for using phosphor marked stamps is “tagging.” Tagging in the United States helps machines sort and flip envelopes so that the stamps can be cancelled more efficiently.

How Do You Find Phosphor On Stamps?

To understand where to look for phosphor on a stamp, you must know:

  • Where it is likely to be placed on the stamp
  • The colors you will be able to see under UV lighting
  • Whether you can see the phosphor bars or film with the naked eye

There are a few different ways a stamp can have phosphor colors applied to it.

In Bars

Vertical or horizontal bars are “printed” onto a stamp and that can be checked via a UV light or in some cases with the naked eye . To look for the phosphor with no visual aid like a UV light, hold the stamp up to the sun.

You should be able to see a raised phosphor stripe or bar running horizontally, vertically, or both, across the face of the stamp. Another method is to use a UV light. This method makes the bars appear more pronounced but is not necessary.

In The Ink

Another way to insert phosphor onto a stamp is to mix it directly with the ink used to make the stamp’s image. The effect is to give any part of an image that has that color ink a phosphorous glow. The ink can be seen in a UV light, but it can also be seen if held up to a bright light. The phosphor infused ink is shinier than normal ink.


This type of phosphor stamp application is when the surface of the stamp has a phosphor ink block applied to the surface of the stamp. The size of the block can vary, as can their placement on a stamp.

Prephosphored Tagging

With this method, the phosphor is added to the paper the stamp is printed on. When put under a UV light, prephosphored stamps have a solid phosphorescence color. Another effect is that the image on the stamp appears bolder than a stamp with a different type of phosphor application.

Popular Colors

While technically any color can be added to phosphor, there are a few that perform better than others. The best and most used colors include:

  • Green
  • Red
  • Yellow
  • Blue
  • Violet
  • Green

Some countries have preferred colors:

  • Canada: Bright yellow in thin bars that run across the stamp
  • United States: Colors for domestic and international mail (green and red)
  • Great Britain: Blue and yellow

Do You Need A UV Lamp To Find Phosphor On Stamps?

You do not need a UV lamp to find phosphor on stamps. Just about every application of phosphor is visible to the naked eye. You can see it when you hold the stamp up to a light source. The one way a UV lamp will help you is to see the colors used with the phosphor.

If you decide to purchase a UV lamp or portable UV device, you do have to get one that can see short and long wavelengths. This will allow you to see just about every type of phosphor stamp that has been produced.

One option if you are looking for a plug-in type of ultraviolet lamp is to look for a used lamp online. You may even want to test it – or have the seller test it – on a stamp to make sure you are getting what you need before you buy it.

Ultraviolet Lamps

There are two types of ultraviolet lamps: plug-in and portable. Each plays an important role when dealing with phosphor infused stamps.

Plug-In Ultraviolet Lamp

Plug-in ultraviolet lamps are stationary and get their power from a standard outlet. These types of lamps are great for longer phosphor examination and work best in a dedicated workspace. They have a powerful bulb and are usually able to see both short and long wavelengths of light.

The number one benefit of a plug-in lamp is that it will typically let you see more details and variants of phosphor markings on stamps.

The downsides to a plug-in ultraviolet lamp include:

  • They get very hot and can pose a fire hazard
  • Prolonged use can result in eye damage
  • They are very bulky and heavy, which makes transporting them difficult
  • They are usually very expensive

Portable Ultraviolet Lamp

Portable UV lamps are handheld pieces of equipment that are battery operated and provide quick scanning capabilities. These work best “on-the-fly” when visiting a stamp show or dealer to verify that a stamp has phosphor. They are also great when you don’t have access to an electrical outlet, and they are fairly inexpensive.

The number one benefit of the portable ultraviolet light is that they are great for authentication to make sure that you do not pay too much for any specific stamp.

Portable UV lamps do however have the following downsides:

  • Unfiltered and weak compared to a plug-in lamp
  • Let off too much white light that obscures any faint tagging
  • Battery power is limited and can run out if the unit is used for too long

Ideally, a stamp collector interested in phosphor stamps will have both types of light as both play a particularly significant role in helping identify and pinpoint phosphor markings on collectible stamps.

Final Thoughts

To find phosphor on stamps, you first need to know where the phosphor is located on the stamp and what method was used to put it there. Once you know these two things, you can usually find phosphor on stamps using your naked eye alone, or you can use a UV lamp.

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