When to Use UV Control Glazing

Have you ever had a framer tell you that you can protect a work on paper from fading just by putting UV (Ultraviolet) protective glass or Plexiglas on the artwork?  Even though your framer is normally the one that suggests when to use UV control glazing, what they tell you may be truthful without being accurate regarding its effectiveness in your situation.

What they should have said is that depending on where a work on paper is hung, UV protective glass and Plexiglass can help protect it from fading. Ultraviolet light is the most damaging part of the light spectrum to fugitive pigments on paper and other materials that are prone to fading, like fabrics and furniture. High end UV protective glazing material is rated to block up to 99% of the Ultraviolet rays hitting an artwork’s surface. Just remember that UV may be the worst part of the spectrum, but it is only a small part of the spectrum that can cause damage. A greater issue is the overall amount of visible light that is hitting the artwork and the amount of time it is getting hit. Think of it as slow or fast fading.

• Little light over an extended period of time = slow fading
• A lot of light over a short time = fast fading

Image of graph showing the entire know light spectrum. What is most important here is the Ultraviolet and viable sections of the light specturm.
Ultraviolet light, the most damaging part of the light spectrum to works on paper, is in the sweet spot between visible light and x-rays. This means that UV is in the part of the spectrum that is higher energy than visible light but the rays do not go through the artwork like x-rays will. The UV rays penetrate the surface and are absorbed by the paper like a sunburn on skin. Because UV light is not visible to humans, removing it from the spectrum by using UV control glazing does not have much effect on the fidelity of an artwork.

If a work on paper was to be hung in a lightless closet, with properly controlled temperature and humidity that is never opened, it does not matter if it has UV protective glazing or not as it will not fade, at least not from light exposure.

If a work on paper is hung in a bright living room with big curtain-less picture windows looking out over a lake that reflects light into the room, even with UV glazing and protective windows the artwork will fade over time and the paper will darken. In the trade, when referring to the darkening of paper by excessive light, an art dealer would say that the artwork has been “light struck.”

two images that show how exposure to light can fade colors in a print.
Left image is unfaded and right image is a composite image showing faded work on the left side and unfaded work on the right.

For most light sensitive materials, light damage is cumulative and irreversible. So, what are the best ways of minimizing the effects of light damage to an artwork on paper?

Museums have different regiments they follow regarding the amount of light exposure each work on paper can have. Each work is normally evaluated to determine how sensitive it is. It is then assigned an allowable exposure schedule, amount of time it can be on view, and a maximum allowable light level for the duration of that time. For example, a sturdy work might be allowed to be on exhibit for 4 months at a specific light level and then rest for two years, or for 6 months at that light level and rest for three years. A more fragile work may require lower light and less time on view.

Don’t Panic! The Museum protocol I have just described is designed to meet the museum’s charge to protect what they have collected or are exhibiting.  Your clients want something they can hang on the wall and enjoy for the next 20 years. So, to accomplish this goal I suggest the following:

• For works on paper that you or your client consider valuable and want to last as long as possible, definitely use UV protective glazing as it greatly reduces the most damaging aspect of the light spectrum.

• Hang in rooms with minimal light during the day like hallways or bedrooms that are not in continuous use and are normally kept dark.

• Keep lights off when rooms are not in use.

• If an artwork is hung in a room that has windows that allow a lot of light into the room during the day, add blackout curtains to the window that can be closed when no one is using the room. Codes for new buildings in most areas require that windows block a lot of the light coming in for reasons of energy conservation. This can greatly extend the life of curtains, rugs, and furniture as well as the art by reducing the amount and intensity of light entering a room and therefore slow fading.

• Have blackout fabric covers made for the artwork in rooms that window curtains are not an option or skylights let light in that cannot be blocked. They can incorporate a weighted rod at the top that can be draped over the top of the frame with the fabric hanging over the front of the artwork. This will allow quick access to works when you want to view them and they can remain hung indefinably without overexposure to light.

These two images show how opaque fabric covers can protect an artwork from fading.  

• Keep these works out of often used bedroom bathrooms and kitchens. These rooms often are subject to high humidity and temperatures, and other issues with that I will address in a future post. They are also rooms that would normally be well lit and where you would not normally want artwork that needs protective covers to keep them from fading.

• Place UV tube covers over your fluorescent lights. Of the three main light sources in homes and offices used today – Fluorescent, Incandescent, and LED – Florescent light, for the same amount of lumens output, is the most damaging because it produces the most UV light.

• If LED lights are producing the same number of lumens as your incandescent bulbs do, they are causing an equal level of fading to your works on paper.

One of the main manufacturers of conservation-grade UV protection glazing is Tru Vue. They have an excellent highly informed and well-educated customer support staff. If you need clarification, again no pun intended, as to whether UV protective glass and Plexi will work in a specific application, give them a call.
Tru Vue help line: Phone: 708-854-2700
Email: fineart@tru-vue.com

Note:  Not that it is my field but I was informed by the folks at Tru Vue that one of the most frequent calls they get is from signature collectors who have used their products and have had their valuable signatures fade from being out on display in rooms that have too much light.  Their glass was doing what it was supposed to but many framers are often not aware that UV glass alone will not stop fading, it only helps to slow it down.  The recommendations I have made above should help with this issue.   Another interesting thing they said is that often, ink signatures seem to fade very quickly to a certain point and then the fading process seems to slow.  So the maximum amount of damage happens in the earliest part of their exposure.


For more information about Framing Artwork, visit these other blog posts:

image of a wall of frame samplesThe Importance of a Proper Frame
Two images showing an image of a flower behind reflective and reflection free glassReflection on the Problem of Reflections


To see all available FAE Design Blog Posts,  jump to the Design Blog Table of Contents.

To see all available FAE Collector Blog Posts, jump to the Collector Blog Table of Contents.

Sign up with FAE to receive our newsletter, and never miss a new blog post or update! 

Browse fine artworks available to purchase on FAE.  Follow us on FacebookInstagram, or Twitter to stay updated about FAE and new blog posts.

For comments about this blog or suggestions for a future post, contact Madeleine at mbogan@fineartestates.com.

What Does That Fraction Mean on a Fine Print?

Over the years, I have witnessed a great deal of confusion regarding fine print editions and what the fraction means, that is usually written in pencil and normally found just below the print’s image in the margin.  I have written three short essays to hopefully bring a little clarity to the subject.  I have also provided a link to a glossary of terms related to the editioning of fine prints.

Part 1:

An overview of the things that you may find helpful to know regarding the modern editioning for fine prints and what the fraction, found in the margin under the image, actually refers to.

Part 2 :

A short case study regarding the editioning of a series of old master prints by Albrecht Dürer (German, 1471 – 1528) called the Apocalypse.

Part 3:

An overview of what I found when I was trying to determine what fine print publisher or which artist was the first to use a fraction to describe the print number and the edition size that is now the universal format.  I cannot say I found the first, but I did find an 1895 reference point that will be a benchmark to beat in the future.

Part 4:

A link to a glossary of terms related to types of proofs and related nomenclature. You are welcome to download this Word file and keep it as a reference.

Note: In conveying the information below, you will see that I have qualified almost every example I have used related to editions or a fraction’s numerator and denominator. This is because in every case described below, in the 40+ years I have been dealing with fine prints I have personally run across exceptions, but they are rare.

Part 1: Numbering and Edition Overview:

After a number of prints have been produced by or for an artist, it is a standard practice to use a fraction to identify both an individual print and the number of like prints the artist has declared that will then constitute an “edition.” With few exceptions, this fraction is written in pencil beneath a print’s image at the lower left or lower center margin by either the artist or the publisher. There are several misconceptions as to what the numerator and denominator of this fraction mean related to the edition of fine prints and I hope the following information is helpful when looking for fine prints for your clients.

Fractional edition number with date. This is the print designated as number 21 in an edition of 30.

The Numerator:
Because written definitions of what the numerator represents are often imprecise and ambiguous, they can easily lead someone to erroneously believe that the numerator indicates the sequence in which the prints of that edition were printed. (i.e. if the fraction written on an etching is 5/25, this would indicate that this print was the 5th print pulled off the plate in a total edition of 25.) In truth, this number does not relate to the print’s printing sequence but is only a cataloguing device, a way of identifying print 1 from print 2, etc. The odds of this print being the 5th one pulled from the plate is, for various reasons, more than 1 in 25.

It is most often the case that the earliest prints off a plate, stone, or block, depending on the technique used, are often considered by collectors and curators to be better and therefore more desirable impressions than those printed later. This is due to the wear and tear on the matrix from repetitive printing.  What is almost in all cases not true is that the numerator of the fraction can tell you if a print was an early impression or not; only its superior quality compared to other impressions of the same print can do that.

The Denominator:
The Denominator of the fraction relates to the total size of the artist’s declared edition of like prints. The term “like” prints is important here as it means that the only thing that is different about each print when the edition is finalized is the numerator of the fraction. Everything else, the paper type and size, the inking of the matrix, and the way it is numbered and signed are all the same. It is important to remember that the denominator just indicates the size of the allowable edition, it in no way substantiates that editioning was completed after its size was declared. It is often only the print documentation from the press that produced it, the artists print log, or a well-researched catalogue raisonné that can enlighten one as to how many prints were actually printed of an edition.

It was popular, in the case of well-known artists like Joan Miró, to have their press print multiple editions from the same plate or stone. For instance, Miró would sometimes authorize a second edition on a different type of paper. So, you might see a print by Miró on Arches paper in an edition of 250 in one place and the same print on Japan paper in an edition of 100 somewhere else. Miró would sometimes authorize a special small edition of a print to be published that was in every way like another edition except that instead of numbering the edition in Arabic Numerals, it would instead be numbered with Roman Numerals. The takeaway here is that there may be more than one edition of a print. This usually does not occur unless the artist’s market is big enough to absorb multiple editions.

With most any known declared edition, there are additional like prints called “prints outside of the edition.” Conventionally, beyond the edition defined by the denominator, a certain number of prints will be printed that will be designated as Artist Proofs. They are like the edition in most every way except rather than being numbered with a fraction, the letters “A.P.,” (épreuve d’artiste in French) or a variation thereof, are written instead. The number of A.P.’s varies with how many the artist wants to have printed but it is rare that they exceed more than 10% of the total edition size of like prints.

Again, in the case of Miró and other printmakers who were well known in the latter part of the last century, another type of print designation was used initially in Europe to boost the number of prints outside of an edition. On occasion you will see prints, instead of being inscribed A.P., inscribed “H.C.,” (Hors de Commerce) or a variant, that means amusingly “not for sale.” Prints with this designation can be found occasionally on the market but they were originally intended to be gifted and not sold commercially.

There are other print edition designations that I will not go into here as the chances of running into them while looking for art for your clients is unlikely. Below is a quick history of editions as they relate to old master prints and to the earliest usages of the fraction to indicate edition size. If you find that you have a question about something on a print that you don’t understand, send us an email with an image and we will get right back to you.

Part 2: Old Master Prints:

Dürer’s “Apocalypse” 1511 title page

Albrecht Dürer (German, 1471 – 1528) was one of the world’s most famous and important printmakers. He produced a series of fifteen large woodblock prints based on, and called, Apocalipsis cum Figuris, known today as the Apocalypse. Outside of proofs printed to test the image and those that were printed to sell or gift, in 1498 the fifteen prints that made up the series were printed with text, some in Latin and some in German on the verso of each image, and bound. Prints that appear on the market today from this edition of books are described as “from the 1498 edition.” This series brought Dürer great fame and notoriety. Because of the popularity of the series, it can be assumed that he continued to print individual proofs from the blocks until he published another bound edition of the Apocalypse in 1511. After that series, where individual prints are now known as “from the 1511 edition,” the woodblocks were printed as the market demanded until they had worn down to the point that they could no longer produce acceptable prints.

Dürer’s woodcut The four horsemen of the Apocalypse

Before Dürer’s time and well into the 19th century, the number of prints off a plate, stone, or wooden block was determined by either demand or the condition of the matrix used that allowed acceptable prints to be created. Today, we would call that an “open edition” because the edition size was not declared by the artist. In the case of Dürer’s Apocalypse, there are two actual editions from the same woodblock of each of the 15 Apocalypse prints and many prints outside of a known edition. When dealing with old master and 19th century prints, date of printing, quality of impression, condition, and notoriety of the image are directly related to the print’s value. In the case of these specific Dürer images, as well as many other old master prints, editions and other proofs can often be dated by the paper it was printed on and the watermark it may bear.

Part 3: When the Numbering of Fine Prints Became Popular…

Most likely inspired by the rare book trade, consensus leans toward the idea that it was the fine print publishers in 1890’s France that started numbering the prints of the editions they published. One of the best known and most important printmakers during that time in Paris was Toulouse Lautrec who was a prodigiously active Lithographer from 1891 to 1900. By using the catalogue raisonné Toulouse-Lautrec: The Complete Prints by Wolfgang Wittrock as a reference, a window is opened into the innovations and practices regarding print numbering and editioning during this period. Here are my takeaways:

• Lautrec signed a small number of his prints but although many of his prints are numbered, it is believed that he did not do this himself; they were most likely numbered by the publisher. In many cases, just under half or just over half of the prints were numbered. The number system most often looked like “No: X” and written in pen or pencil. In some cases, stamps were used to number the prints. It is not clear why only half of an edition was numbered as it creates a very ineffective inventory system. *1

Lautrec’s “Mademoiselle Marcelle Lender” color lithograph

• The states (prints that show developmental changes) and edition sizes of most of Lautrec’s prints are known but the edition size was rarely indicated on an individual print.  In reviewing all the print entries in Wittrock’s book, there are only five times that a fraction was used to indicate both the prints assigned number and the number of prints in the edition. The first time a fraction was used on a Lautrec print was 1895 on half of the Pan French Edition of 100 prints of Mademoiselle Marcelle Lender, en buste, (Wittrock 99.)

Wittrock’s entry for the Pan French edition of Lautrec’s “Mademoiselle Marcelle Lender” color lithograph

*1 – Today, fine art presses will often publish artists’ prints by offering them studio space, possibly room and board while they are working, and then printing an edition of what the artist produces in exchange for a percentage of the edition. This way a press will have an inventory of prints by artists they respect, and the artist keeps the rest of the edition.  It is known that most all of Lautrec’s prints were sponsored by the publisher and very few print editions were paid for by him. This may account for the fact that often, only about half of his prints’ editions were numbered by the press.

Part 4: A Glossary of Terms Related to Types of Proofs and Related Nomenclature

Back in 1989, a colleague named Frederick McElroy, who had a masters in printmaking, and I decided that we would create an exhibition that focused on both the connoisseurship and technical aspects of Intaglio printmaking.  One of the dealers we work with in Austin Texas who owns Flatbed Press suggested that this glossary would be a good addendum to the article above.

You are welcome to download the glossary as a word file by clicking Here.  You are welcome to print yourself a copy for reference if you like but if you quote any of these entries in a publication, please credit Fredrick W. McElroy and cite the exhibition catalog Connoisseurship and the Intaglio Print, 1989.


For more information about Fine Prints, visit this other blog post:

a panoramic image of the press room of a fine art publisherThe Value in Fine and Reproductive Prints


To see all available FAE Design Blog Posts,  jump to the Design Blog Table of Contents.

To see all available FAE Collector Blog Posts, jump to the Collector Blog Table of Contents.

Sign up with FAE to receive our newsletter, and never miss a new blog post or update! 

Browse fine artworks available to purchase on FAE.  Follow us on FacebookInstagram, or Twitter to stay updated about FAE and new blog posts.

For comments about this blog or suggestions for a future post, contact Madeleine at mbogan@fineartestates.com.