I do not understand why a 100% natural mattress is covered with non natural viscose fabric. Why do you use viscose?
In the answer to a similar question it says there is a 60/40 split damask/viscose - that is not what is stated on the item detail page which specifies "This mattress is covered in our white woven 100% Viscose with subtle John Ryan design". This applies to the 85% natural and 100% natural mattress models.