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Subject: Thermal transfer labels

Thermal transfer labels

From: Karin von Lerber <karin.vonlerber>
Date: Friday, August 4, 2000
Chip Larkin <chiplarkin [at] att__com> writes

>Has anyone had any experience with thermal transfer printed labels?
>We are considering these type of labels for item and shelf location
>barcodes. The labels would not be adhered directly to items unless
>there is some sort of barrier between the item such as a Mylar
>sleeve, case, etc., loose labels would be used instead.

We have used exactly this system to prepare 15,000 objects for a
move, and we are continuing to use it for large scale projects.
(Cost efficiency is too low if less than say 5,000 objects have to
be labeled).

The lables we used were polypropylene. We had one of them hanging on
the south wall of our office (outdoor temperatures from hot to
frozen, rain etc.) for over two years. It was only after two years
that the plastic started getting brittle and could be broken easily;
the print was unfaded and seemed to have the same properties as
before this extreme exposure.

The only problem with the thermotransferr barcodes is, that they
might get scratched. If the scratch happens to be exactly on the
diagonal, you won't be able to read the barcode anymore. We
therefore (and for other reasons) chose to also print the Inventory
Number in "human readable" language, and to only translate the
Inventory number (without further codes or titles) into bar code.
Like this you can always enter the number manually if you won't be
able to read it with the hand held tool anymore. And if your
institution in later years can't afford the bar code system anymore,
the numbers still stay readable. Just to make it clear: in our view
barcode labels do *not* replace the Inventory number written onto
the object, as they might get torn off. They are an additional tag,
visible on a larger distance and facilitating speed and accurateness
in registration of objects as they change place (during moving a
collection, during work at the lab, during exhibition, loan etc.).

There are two potential problems with thermo transfer printers: They
need to be hot to produce good quality printing. Used under 10 deg.C
room temperature, the print is not burned in well enough. This turns
out a problem when you are working in an unheated storage area
during winter. The other problem lies in the *foil* which is printed
onto your labels by heat. We chose 3M, but we know they had at the
time considerable differences in quality from one batch to the
other, caused by their change to more environmentally sound
materials. This phase might be over now, but we suggest you test
every batch on arrival.

As we had to label the objects as fast as possible, we did not take
the time to attach the labels with thread for all objects. For more
sturdy objects (such as furniture, wrought iron pieces, tools etc.)
we attached the labels with nylon fasteners (the type often used for
ski-lift day cards in Europe). We know, that nylon will decompose
under UV. But as there should be no UV in storage anyhow, and as the
surface amount of these small fasteners compared with anything else
is very small, we decided to use them. We also added some of these
fasteners to our south facade outdoor test. After two years one of
the fasteners could be torn apart only in one spot (which was where
it touched the metal wire used to hang all the labels) with applying
a lot of force; the others still don't break. None of them shows any
yellowing at all. I think nylon very much varies from batch to
batch, so you might want to test whatever fasteners you chose

As far as labeling of the shelves is concerned, we used
self-adhesive labels from 3M (Polyester, white glossy, Nr. 3M 7816,
"scotchmark") which are normally used for medical purposes. Their
specification is such that they have to stand 5 cycles of
sterilization heating without any perceivable damage. And I assume
for medical purposes outgassing of the adhesive would be
unacceptable. We do have the materials sheet for these labels, but
3M won't tell what adhesive exactly they use (they state a
water-based polyvinylacetate). We were very satisfied with these
labels. They stick on any smooth surface like metal and plastic, but
not on wood. Their only disadvantage is, that they don't stick on
cold surfaces (e.g. outdoor storage). You would have to wait until
the base material is warm enough. Once attached, the labels should
stand the cold. Before writing this statement, I shortly tested this
in my freezer (attached onto a polyethylene plastic bag) for 4 hours
with the result that the label is still sticking. It can, however,
be peeled off more easily as long as it is frozen; 2 minutes out of
the freezer, I could not peel it off the plastic anymore again.

If you would like to have more information about labels, barcode
systems or our logistical systems (e.g. numbering system of storage
facilities etc.), don't hesitate to contact us off line.

Karin von Lerber
Prevart GmbH
Konzepte fur die Kulturgutererhaltung
Oberseenerstr. 93
CH-8405 Winterthur, Switzerland
+41 52 233 12 54
Fax: +41 52 233 12 57

                  Conservation DistList Instance 14:11
                  Distributed: Sunday, August 6, 2000
                       Message Id: cdl-14-11-002
Received on Friday, 4 August, 2000

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