After having used-up my stock of Archival Methods 4-ply Museum board I started on my stock of 4-ply Archival Methods conservation board that I had (might as well as use it since I already paid for it). No I'm out of both and need to reorder. My past preference has been for Museum Board which is why I never used the Conservation Board until now. While it doesn't “feel” as good as the Museum Board, I came to prefer the “pearl” coloration of the Conservation Board over the Museum. How do the archival qualities of conservation board compare with those of Museum Board? From the Archival Methods website:

Features: Conservation Board uses alpha-cellulose pulp from purified wood fiber and is therefore more economical to manufacture than cotton Museum Board, yet carries with it the same stable and long-lasting properties. Purified wood pulp paper has a long history of being safe to use with paper artwork, photographs and documents. Our high quality Conservation Board is acid- and lignin-free, and incorporates alkaline or neutral sizing. All boards are buffered with calcium carbonate. This ensures protection from the destructive effects of acid migration from the matted work and from a polluted environment that might cause the pH of the mat board to decrease (become more acidic) with age. No optical brightening agents are used in the manufacture of our Conservation Board.

Specifications:
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Conservation Board uses alpha-cellulose pulp from purified wood fiber
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2-Ply / 30 Pt. (Approximately 1/32’’)
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4-Ply / 60 Pt. (Approximately 1/16’’)
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Alkaline sizing is used for both internal and external sizing. No alum is used in the manufacturing process.
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Buffered with calcium carbonate 2-3% alkaline reserve, pH 9 ±0.5, acid–free.
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Color dyes are light-fast and non-bleeding.
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Board will not degrade and cause harm to mounted matted artwork.
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Lignin content is tested by TAPPI 236 cm-85 and has a Kappa number of less than five.
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The single ply sheets are laminated together using all natural starch adhesive.
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Board passes the PAT (Photographic Activity Test) ISO 14523 (formerly ANSI IT9.16).

Thomas