Polyethylene deterioration

On behalf of Ginette Clement, Kateri Morin <kateri_morin [at] pch__gc__ca>
writes

>    ... Information gathered from the conservation
>    reports led us believe that in many instances the bags were made
>    in 1983 and all were done in the same lab. ...
>    ...
>    ... This would
>     suggest that this degradation is associated with the quality of
>     polyethylene sheet used.  We would appreciate any of your
>     storage stories or observations that might help us.

It is not unusual for plastic bag makers to add "slip" or other
additives to make the manufacturing process easier or more
efficient.  This is especially true when very light weight poly bags
(eg garment bags for dry cleaners) are made. These added chemicals
are likely the cause of the deterioration.

When purchasing plastic bags, try and ascertain from the plastics
convertor (the industry moniker for bag maker) the actual content of
the plastic used. You may have better luck specifying "food quality"
when you next order.

Jerry Shiner
Keepsafe Systems  800-683-4696


                                  ***
                  Conservation DistList Instance 16:75
                  Distributed: Thursday, May 29, 2003
                       Message Id: cdl-16-75-003
                                  ***