For photosensitive materials, which glass type is used?

• A. Low actinic glass
• B. High actinic glass
• C. Soda-lime glass
• D. Borosilicate glass

Answer: (A)

Actinic radiation refers to the UV and blue portions of light that can cause photochemical changes in photosensitive materials. To handle, view, or store such materials safely, you want glass that blocks or greatly reduces these actinic wavelengths while still allowing visible light to pass. Low actinic glass is designed to do just that: it transmits visible light for viewing but absorbs the shorter, more energetic wavelengths that would otherwise fog or react with the photosensitive material. That protective blocking is why it’s the best choice for handling photosensitive materials.

In contrast, high actinic glass would allow more actinic light through, increasing the risk of unintended exposure. Common soda-lime and borosilicate glasses transmit considerable UV and blue light, so they don’t provide the needed protection for photosensitive media during handling.