Staedtler Mars plastic erasers

I have recently noticed a definite change in the Staedtler erasers
for the electric erasing machines.  Last week I opened a new box,
purchased in February 2012, and the texture and working properties
of the erasers are completely different than the older ones. Instead
of creating nice dry eraser crumbs, it almost seems to be melting on
the document, leaving behind a sticky lump that cannot be brushed
away but must be rolled off with the fingers.  We bought 20 boxes of
these refills at the time, and I have tested half of them, all with
the same results.  They're not only practically unusable, but the
change in working properties makes me seriously concerned about what
the formulation of these erasers may now be, and if they are still
safe to use for cleaning documents.

I have contacted the Staedtler company to ask if the formula for the
erasers has changed, or if I may have just received a bad batch, but
have not received a reply.  On their website, on the erasers page,
is the following, "Discover the Staedtler erasers with an improved
formula for superb results when erasing graphite, ink and drawing
ink on matte drafting film and overhead transparencies."  This
doesn't leave me much hope that we just received a bad batch.

Has anyone else noticed a difference in the new Staedtler erasers,
or does anyone have any information about what might be going on
with the Staedtler erasers?  Any information would be greatly
appreciated.

Sandy Hempe
Conservator
Missouri State Archives/Local Records Program


                                  ***
                  Conservation DistList Instance 26:13
                  Distributed: Sunday, August 19, 2012
                       Message Id: cdl-26-13-026
                                  ***