Gray-White Board - This is the material for the United States National Archives and Records Administration according to their specifications. The board is sulfur free with a minimum pH of 8.5 and 3% calcium carbonate buffer throughout the sheet. Both the gray outer liner and the white inner liner are lignin free and conform to the ISO 14523 Standard. TAPPI accelerated aging tests show that this board will prevent acid migration for at least two centuries. The sheets are 60 point caliper with a gray exterior and a white interior. Archives Board has a basis weight of 200 lbs. per thousand square feet and a Mullen bursting strength of 240 lbs. per square inch.
Beige Board - This is a fully bleached fiberboard with is lignin and sulfur free and conforms to ISO Standard 14523. The material has a minimum pH of 8.5 and a 3% calcium carbonate buffer. The sheets caliper 60 points and have a basis weight of 225 lbs. per thousand square feet with a Mullen bursting strength of 275 lbs. per square inch. Board color is beige throughout.