Why glaze? Glass or acrylic?
Photographic art work displayed on a wall for many years requires a protective cover.
Dirt, oil and grime accumulates on walls. If you doubt that, take a damp white towel and wipe a nearby wall. If the wall hasn't been painted or washed recently, the towel will be dingy. That ding will cover a displayed photograph within a year. Unfortunately, cleaning the art with a rag will damage it. A protective cover addresses this problem.
A protective cover that can be cleaned will also absorb UV light and shield against ozone and other atmospheric chemicals that accelerate fading and yellowing.
There are two ways to protect the surface of the photographic art. One way is to spray the surface with a protective coating. Photographic art protected with a coating can be gently and cautiously cleaned. Unfortunately, over the 100 year lifetime of an archival print, the protective coating may crack and is likely to yellow resulting in a shortened display lifetime.
A better way to protect photographic art is to display it under glass or acrylic that's held slightly away from the surface of the artwork by a spacer such as a mat. The spacer keeps the art from touching the glass or acrylic avoiding damage caused by humidity changes that may stick the art to the surface of the glaze.
A glaze that can be cleaned or removed without damaging the print is the safest protection. But which is best: glass or acrylic?
Acrylic is plastic. It has a tendency to build a static electric charge that attracts dust. Like most plastic, acrylic is more easily scratched than glass. As an organic material, acrylic plastic can yellow over many decades. Fortunately, acrylic is relatively inexpensive and can be replaced. Also, acrylic is much lighter than glass and does not shatter if dropped.
Glass with its harder surface is much easier to clean. It may also be more transparent than acrylic. However, glass is more likely to have a very slight greenish tint than acrylic. That tint may affect the beauty of the art work.
When shipping glazed art, the weight and risk of breakage from glass often precludes its use.
Glazing any art creates a barrier between the art and the viewer. Glazing also makes reflections more prominent and important to manage. Very expensive non-reflective glass is available, but often with a trade-off of image sharpness and contrast. Often images displayed under museum grade glass appear softer. In my opinion, it is more cost effective and better to manage the lighting and display location so that ordinary glass can be used.
For my own photographic art, I display prints in ordinary glazed frames that I purchase locally.
I will use acrylic when shipping for the lower cost and less chance of breakage.