Wrapping material for plastics

Marcia Bassett <marcia.bassett<-a t->gmail< . >com> writes

>I just unpacked a number of small plastic boxes that were wrapped in
>tissue.  The tissue has left a white dust on the boxes which can be
>wiped away; however, I am wondering if there is a recommended
>wrapping for plastic objects.  I am thinking of using archival soft
>Tyvek or ploy bags.  Any suggestions would be appreciated.

Suitable packaging materials for plastic objects are dependent on
the plastic type and its major degradation pathway.  Acid-free
tissue is suitable for cellulose nitrate and acetate which evolve
acidic gases as degradation products.  Tissue allows the gases to
escape thus reducing the risk of autocatalytic degradation which
occurs significantly faster than the initial hydrolytic breakdown.
The packaging tissue may be degraded by the evolved acid indicating
that the storage microclimate is unsuitable.  PVC should not be
packed in Tyvek (high density polyethylene) or other polyethylene
bags or foams because these adsorb phthalate plasticizers readily
from the object and result in further degradation.  Polyester, such
as Melinex or Mylar does not adsorb plasticizers and is therefore
suitable for PVC.


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                  Conservation DistList Instance 27:37
                  Distributed: Sunday, March 30, 2014
                       Message Id: cdl-27-37-003
                                  ***