Bleaching

Bleaching

Bleaching is a chemical process applied to alpha-cellulose mat board in order to whiten its core. This whitening treatment ensures that when the mat is cut at a beveled edge, the exposed core appears clean and bright, rather than dull or discolored. The process improves the visual appeal of the mat and ensures consistency across different colors and finishes of mat board.

Purpose and Applications

Bleaching plays an important role in the production of mat boards by:

• Providing a clean white core that enhances the crispness of a beveled mat opening.
• Preventing the appearance of unwanted yellow or gray tones along cut edges.
• Allowing greater design flexibility when pairing mats of different colors.
• Improving the overall presentation of fine art, photographs, and collectibles.

Conservation and Archival Considerations

Not all bleaching processes are conservation-safe. While many modern manufacturers utilize safe methods that leave the mat board pH-neutral or buffered, some lower-quality mats may be chemically unstable. Over time, improperly processed materials may contribute to acid migration and eventual artwork deterioration. For archival framing projects, it is best to use mats specifically marketed as acid-free or museum board.

Design Considerations

• Consistency: Bleached white cores help maintain visual consistency across different mat colors, especially when multiple mats are stacked.
• Contrast: In comparison to black core mats, bleached white cores provide a cleaner, more neutral look that emphasizes the artwork rather than the border.
• Reverse Bevel Cuts: When using a reverse bevel, the bleached edge is hidden, making bleaching less relevant in those cases.

Common Misconceptions

• "All white cores are bleached": Some mat boards are naturally light due to the raw material, while others achieve brightness only through chemical bleaching.
• "Bleached mats are always archival": Archival quality depends not only on bleaching but also on the lignin content and the pH balance of the board.

Related Terms

• Bottom Weight
• Mat Color
• Reverse Bevel
• Black Core Mat