Storing plastic

Ana Sofia Silva <anasfsilva<-a t->gmail< . >com> writes

>I am currently working on a project that involves objects made of
>plastic, and most of them are celluloid objects that need to be
>...
>Another idea that crossed my mind is to store these items inside a
>perforated plastic container and make use of paper absorbents like
>MicroChamber to help in slowing the rate of deterioration and
>affecting other surrounding materials. ...

First, I believe you are on the right track with your thinking.  If
cold storage or isolation are truly impossible, then enclosure in
perforated inert materials surrounded with
super-absorptive/neutralizing materials is probably a good idea.
Another would be a case designed just for these objects with active
filtration and air circulation, but I am assuming the cost for this
would be prohibitive.  Remember, even lowering the storage
temperature 5 degrees can help slow deterioration.  Also, lowering
humidity and excluding oxygen can also increase longevity.

Second, not all cellulose nitrate was created equal.  Imitation
ivory and other opaque objects usually contained fillers that act to
stabilize the plastic, and so are less of a concern than the clear
plastic, which often deteriorates much faster.  If you have any that
are crizzled or actively disintegrating, they are of greatest
concern (they are the most flammable, the most actively off-gassing
and increasingly hygroscopic), and MUST be dealt with asap.

If none of your objects show signs of deterioration, than it may be
that they can be kept safely in the way you describe for some time.
This would still require adequate monitoring and renewal of the
absorptive materials when exhausted.  You can monitor acid
production with papers that are impregnated with acid-sensitive
dyes.

Concerning which materials are safe to use, I have seen
microcrystalline wax and polyethylene turn yellow when exposed to
deteriorating CN and nearby iron alloys go very rusty.   Remember
also that camphor as well as nitrogen dioxide is being given off.
Camphor is mostly harmless, however, a build-up can cause a
softening effect on some plastics. Since I have not worked with
cellulose nitrate objects for some time, I do not know exactly which
modern materials to recommend to you, but I hope some of the above
thoughts are at least helpful.

Linda Roundhill
Art and Antiquities Conservation, LLC
Woodinville WA


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                  Conservation DistList Instance 27:40
                  Distributed: Friday, April 18, 2014
                       Message Id: cdl-27-40-002
                                  ***