Welcome, Jedimagic3.
...I asked the framer to do anything he could do to preserve the prints.
As many have stated on the thread having no gap is not doing this?.
Preservation framing includes an air gap when using glass, regardless of whether it is coated for ultraviolet filtering, or anti-reflection, or both. There are several potential problems:
1. Dew point condensation -
Google it for a complete explanation. This is probably the most common and most destructive of the hazards when art is pressed against glass. Essentially, moisture condenses on a surface, such as the inside of the frame glass, when the surrounding air is about 20 degrees-F warmer than the surface, but condensation occurs faster when humidity is high and slower when humidity is low. FYI, the interior of a typical picture acclimates to ambient conditions constantly, including fluctuations of temperature and humidity, but a tightly-closed frame slows the rate of change inside the frame. The best way to avoid dew point is to slow the rate of temperature change when humidity is present.
An extreme example of dew point condensation, a phenomenon of natural physics, would be the condensed water dripping on the outside of a glass of icy cold beverage. That happens because the air is warmer than the glass surface. Note that when the ice melts and the contents of the glass warm up to the ambient temperature over time, the condensation stops and evaporation begins. Eventually, the moisture would evaporate and the outside of the glass would become dry.
2. Abrasion - Normal expansion/contraction cycles can impose a slight scrubbing action between the art surface and the glass. This is more problematic when the frame is subjected to rapid or radical changes of temperature, and less an issue when the ambient temperature is constant.
3. Sticking - Some art media, including some inks, can stick to the glass, especially when moisture gets into the frame. Aside from ambient humidity, moisture can enter when liquid glass cleaner drips down & under the frame lip, then wicks back up into the porous framing materials. The most common symptom is a tideline along the bottom edge of the art or mat.
Exception: When it is beneficial to press the art against the glazing, such as in Direct Contact Overlay (DCO) framing, acrylic is much better than glass. Glass is never recommended for direct contact . Here are three reasons why acrylic is a safer choice:
A. Plastic is a much better thermal insulator than glass, so it slows the rate of internal changes and avoids dew point conditions in all but the most extreme ambient changes.
B. The plastic sheet is normally thicker than glass, further slowing the penetration of temperature changes.
C. The plastic sheet's surface is softer than glass, so the abrasion hazard is reduced (does not apply to anti-reflection-coated acrylic).
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Here is a short video demonstrating some of this designer's mechanical wizardry. And here's a picture of him setting it up for a public demonstration, which he does a lot:
