Hi Katie,
The resources that I found recommended synthetic padding, which provides a good barrier between the rug and the floor and is also inhospitable to pests.
The Victoria & Albert Museum's Carpet and Rug Care guidelines suggest "a synthetic underlay, such as polyfelt, beneath carpets and rugs if they would otherwise lie on stone or floorboards. This protects them from abrasion and from being stained by floor finishes (e.g. wax) and also reduces the risk of insect infestation. Traditional woollen underfelt is very attractive to moths and carpet beetles and can harbour infestation."
National Park Service guidelines add that "Some synthetic padding (Dacron polyester) has a non-skid surface that is placed against the floor to prevent the rug from slipping. Avoid rubber non-skid pads, jute, and horsehair."
Since you will be placing furniture on the rug, you might also consider advice from the Wintherthur/University of Delaware Program in Art Conservation's Attics and Basements and Closets, Oh My! Part 7: Rugs and Carpets that "The use of furniture cups is recommended to mitigate the deformation of the carpet's pile. If commercial furniture cups cannot be purchased, small discs of archival corrugated cardboard can be used in place."
I recommend reading through each of these resources for more information on how best to care for your rug, and please write again if you have more questions!
Rebecca
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Rebecca Smyrl
Connecting to Collections Care Monitor
Assistant Conservator for Special Collections
UNC Chapel Hill Libraries
Chapel Hill NC
(919) 962-4250
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