The core and back of the board are acid free but not the surface paper.
Acid free mat board difference.
Moreover they wanted the lignin free acid free matboard neutralized to protect against free floating acid in the air.
What they wanted was a mat board that was 100 lignin and acid free through and through.
What does acid free actually mean.
Rag mat boards come in 2 thickness 2 ply and 4 ply.
Jodie we have two levels of foamboard acid free and artcare acid free that provides a little more protection.
If your mat board is of an economy grade we recommend the white rpb boards or for something thicker the standard or acid free foam core offers more support for larger artwork.
What you need depends on how archival you want to get.
The mat board companies obliged coming up with a new product for the ultimate in protection the aptly named museum board.
If you do want to provide additional barrier between the print and the foam you will want to use 100 cotton rag mat board which is naturally inert.
For any original artwork we recommend a conservation quality backing to go with any conservation or museum grade mat board.
4 ply is roughly the same thickness as regular mat board.
Rag mat board is made from cotton.
Backing boards come in any size.