Wrapping material for plastics

Yvonne Shashoua <yvonne.shashoua<-a t->natmus< . >dk>

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.

Thank you for responding to my query regarding wrapping for plastic.
The plastic boxes are similar to slide boxes and made in the early
1970s.  I assume they were made from molds--most likely they are
acrylic.  Do you recommend acid-free tissue for this type of
plastic?

Marcia


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                  Conservation DistList Instance 27:40
                  Distributed: Friday, April 18, 2014
                       Message Id: cdl-27-40-005
                                  ***