The 25-pack antique white 11 x 14" 2-Ply 100% Cotton Museum Board from Archival Methods is suitable for matting, mounting, and preserving valuable documents, fine prints, and photographs. When used for window mats and mat backing for small prints, the 2-ply thickness of each museum board provides a 1/32" separation between artwork and glazing, thus providing flat and sturdy support. Made of 100% cotton fiber without any brightening agents, this museum board is acid and lignin-free and ensures protection against the destructive effects a polluted environment might cause as your artwork ages.

For Matting & Mounting Fine Art Prints    Acid and Lignin-Free Cotton Fiber    Protected Against Acidic Destruction    100% Cotton Fiber

100% cotton fiber pulp (99% alpha cellulose). It does not contain any post consumer waste recycled pulp. Paper is free of metal particles, waxes, plasticizers, and residual bleach peroxide. Sulfur content is less than 0.0008% reducible sulfur. Iron content does not exceed 150ppm and copper does not exceed 6ppm. No optical brightening agents are used in the pulp.

Alkaline sizing is used for both internal and external sizing. No alum is used in the manufacturing process.

Buffered with calcium carbonate 2 to 3% alkaline reserve; pH 9 ± 0.5; and acid-free.

Color dyes are light-fast and non-bleeding.

Pass the PAT (Photographic Activity Test) ISO 14523 (formerly ANSI IT9.16).

Lignin content is tested by TAPPI 236 cm-85 and has a Kappa number of less than 5.

The single ply sheets are laminated together using all natural starch adhesive.

Related Questions and Answers

Q: 1. Is the sigma 100-400mm compatible with sigma teleconverters?

A: Hi, yes the Sigma teleconverters for Nikon, for instance, are compatible with the Sigma 100-400mm lens for Nikon.

Q: 2. Is the sigma 100-400 compatible with a Nikon D7000?

A: I had read recently that as long as the D7000 has the latest update, that it would be compatible. So I tried it with mine yesterday, and it seemed to function very well. The autofocus was very fast, and all of the exposure readings functioned as well. It was during the late afternoon/evening hours with overcast, so the lighting wasn't all that great, but it functioned as expected.

Q: 3. Does the lens ship with the latest firmware?

A: While we can not check the firmware of a individual lens, our inventory turns over very rapidly and is usually on the most current version.

Q: 4. Is the lens manageable without the tripod collar?

A: I find mine to be manageable hand-held even in situations where must focus manually.

Q: 5. Does the focus ring rotate during autofocus? I see internal focusing as a feature, but thought that only meant the lens doesn't move in and out. I've seen some lenses that are useless with a circular polarizing filter because the lens turns the filter as it focuses. Is this the case with this 100-400mm?

A: This lens has internal focusing, so the focus ring would not move.

Q: 6. Is this sigma 100-400mm lens is rain proof?

A: It's not rain proof but water resistant. I've just finished 2 days of shooting (3000+ images) in constant wet snow without a cover on the lens without any problems.

Q: 7. Will this lens work on a Nikon D3200?,when I click on compatibility 3200 isn't there.

A: According to Sigma's compatibility list located at https://www.sigma-global.com/en/lenses/cas/product/popups/lenses-correspondence/, it is compatible.

Q: 8. Does this lens have a zoom lock to prevent lens creep while carrying it?

A: Yes, it has a zoom lock

Q: 9. Which lens is better overall (build quality, weather sealing, image quality, focus and value) the Sigma AF 150-600 F/5-6.3 DG OS HSM C or the Sigma 100 - 400mm F5-6.3 DG OS C?

A: Both lenses are under the Sigma Contemporary line. They have the same construction. Optical quality on the Sigma 150-600mm f/5-6.3 DG OS HSM Contemporary Lens slightly higher considering you have a longer zoom range.

Q: 10. How's the autofocus speed and accuracy and the OS ? As many reviews says these are the thumbs down.

A: I think it's pretty good actually. I use mine for taking bird photos mostly and I'm happy the speed of autofocus and the overall results.