COVER THAT PRINT

Ways to Protect Your Paintings and Photographs

If you have ever dug up an old newspaper out of the attic, or tried to take a photo out of the album you put together 40 years ago, you have noticed some changes. Not in your ability to find the darn things, but in the colors. The newspaper has browned. Those treasured photos have faded. The primary reason for that fading is that most paper made from pulp has a chemical called a lignin added. Lignin is sensitive to light and acid. 

A previous article covered print choices but did not go into all the reasons to choose one photo paper over what you can do to protect the print that is ready to hang. This article provides more detailed information about print papers and the products that are used to cover our prints. 

Manufacturers go to great lengths to produce lignin-free products. These are their archival papers that are used by photographers for very long term print stability. These archival or museum quality papers are almost always thicker, which provides additional stability against warping or waviness of the mounted print. To achieve extremely white papers, compounds called OBEs may be added. These are essentially a paper bleaching material. OBEs are quite stable, but they do diminish in the paper with time, so that these whitest papers may become a bit off-white with time. The photographer wanting to achieve the purest whites in prints may still use these papers as the best choice.

There are three basic products used to protect the outside of photographic prints. As a group we call them glazing. Without glazing, the print may be scratched, gather dust, or receive fingerprints or other discoloring elements, especially when exposed to the public. These products are coatings, glass and and acrylic. They are each discussed.

Coatings

Coatings are typically used over prints on metal, canvas prints and paper prints mounted to a substrate such as aluminum, Sintra, or foam core. The coating allows the surface to be gently cleaned so that the inks are not affected. These coatings are relatively soft, however, and are susceptible to scratches. Like the other products we will cover, coatings come in various reflective properties. Highly reflective gloss finishes allow the purest rendition of colors from the prints, but light reflections may be seen from nearby lights or windows. Semi-reflective finishes or textured finishes reduce the saturation of colors but are easier to see in challenging lighting situations. The coatings contain photo initiators (camphorquinones) that allow the acrylic resin to be hardened with UV light. Most of the change in color of the coating occurs during this hardening process, but these products can be expected to continue to yellow slightly with time if the print is exposed to UV light.

If you have a particular location to hang a print, try hanging another glass covered print in that location and see how the existing lighting affects the visibility of the print. Most photographers strongly prefer gloss finishes for their prints. An exception to this would be prints with pastel or muted colors. I recommend the gloss finished prints wherever acceptable. In commercial settings, a non-reflective print may be more effective for advertising purposes.  It has to be seen to have an effect!

Another choice is to mount a paper print on Dibond or aluminum and cover it with a thin polyethylene film (Protac) bonded to the print with a pressure sensitive adhesive. This film provides protection for a print but is generally not used for archival prints.

Glass

Glass has been the traditional glazing for prints. The downside is the reflectivity and easy breakage. The biggest upside is that it is easy to clean. The glass found in inexpensive frames is regular, clear picture glass. It is inexpensive, but does not have any properties added to protect your fine prints. UV protective glass will protect your prints from harmful sunlight or interior lights. To be effective without affecting the quality of the print, look for UV protective glass described as blocking 99% or more UV light. This glass may be referred to as conservation glass. Museum Glass (Tru-Vue) also blocks 99% of UV light but adds two optical layers that greatly reduce reflections. It is expensive, but ideal for treasured pieces of art. If you only need a sheet of glass, check out Michael's "Masterpiece" Glass. They sell it the way Costco sells chickens. Some users say it is basically the same product as Tru Vue Museum glass. The price at Michael's is much lower than the price of Museum glass. Museum glass and Masterpiece glass are manufactured (coated) by the same company that claims the production standards are different (lower) for Masterpiece glass. United Manufacturers offers better prices for Museum glass if you are willing to buy additional sheets in specific sizes or can cut to size. If you get a chance, compare the two options and determine your own preference.

You may wish to choose a non-reflective glass in situations where glare would interfere with the enjoyment of the print more than the accompanying loss of clarity. If your print does not merit Museum Glass, consider a standard glass that has non-reflective coatings. This glass does not provide UV protection and it does reduce light transmission by 3% or more. For crisp, highly saturated images, this is not such a good idea as the photographer’s original intent will not be seen. Limit non-reflective glass to image that already have softer colors and when reflections must be minimized.

If you have purchased an inexpensive frame to hold a treasured print, change out the glass. The easiest way to do this is at a local frame shop. Most Aaron Brothers (in most Michael’s stores) sell a 99% UV filtering conservation glass for about $15/sq ft. Museum Glass is available from most frame shops at around $25/sq ft.

Acrylic

The major advantages of acrylic are less weight (about half that of glass) and it does not break very easily. That makes it the better choice for pieces that must be shipped or moved often. Another advantage is that images behind acrylic can be frameless. The largest downsides of acrylic are that it can scratch and it is more costly than other materials. Care must also be given when cleaning acrylic. Ammonia containing window cleaners should not be used. Like glass, acrylic comes in a completely clear version without UV protection and a UV protective version. The most popular version of the latter is Optium Museum Acrylic (Tru-Vue) with 99% UV protection. Also like glass, it comes in a low reflection version. 

Due to its lighter weight and durability, acrylic is highly recommended rather than glass for larger pieces. It is especially popular to mount photographs to 1/8 or 1/4 inch acrylic sheets so the print is seen through the acrylic. This gives the print a more three-dimensional appearance, especially when metallic inks are used. A backing of a solid material is added to protect the print in the same way it might be added to stiffen a large aluminum print. 

Top grade protective acrylics are priced at about $25/sq ft for 1/8 inch thick pieces suitable to place in picture frames and $50/sq ft for 1/4 inch thick acrylic for face-mounting purposes. Part of this high cost is made up for by not needing a frame or mat. The high cost of acrylic is why you see many photographers exhibiting metal prints rather than face-mounted acrylic prints at art fairs and smaller galleries.

A final word of caution when shopping for acrylic face-mounted prints. It is possible to use an inkjet printer directly on the acrylic. The result and the expected life will be quite a bit different than what you see from a print on photo paper that is then mounted to the acrylic. 

RS