CSI (Conservation Special Investigation): Blaschka

Like forensic investigators, conservators collect, examine, and document evidence to help solve mysteries. This is the story of one such investigation.

A group of Blaschka models in storage, some no longer
attached to their original support cards.

The Backstory

The incredibly life-like and detailed invertebrate models made by Leopold and Rudolf Blaschka in the mid to late 19th century were used as teaching tools in universities all over the world. Many of the models were neatly glued or wired to paperboard cards, which provided a safe way to handle the fragile models but also contained their identifying information including the name of the species and the Blaschkas’ catalog number.  

When Cornell University’s collection of Blaschka models came into the care of The Corning Museum of Glass in 1963, the models were in various stages of disrepair and many were already detached, and sometimes separated, from their original cards. While this was likely not a problem for the biology students who originally used them (and knew what species they represented), some of the models entered the Museum with the wrong cards or completely unidentified.

Correctly identifying what these models are and, where possible, reuniting them with their original paperboard cards is part of a multiyear project to clean, re-house, and re-organize the Blaschka holdings at the Museum (which include over 350 models and hundreds of loose and broken glass bits).

Something is amiss

When I came upon this model, I knew something wasn’t quite right. The model was separated from its card, not in itself unusual for these objects, but the faint outline of where the model had been on the card and the glue that had attached it, did not match the size or shape of this model.

The model’s shape does not match the size and shape of the glue on the card.
The clues: the red arrows point to the faint outline on the card where the original model had protected the card from dust and dirt. The green arrow points to the mostly clear remains of the original glue used to attach the model to the card. The blue arrow points to a much darker and messier glue used to re-attach the model or parts of the model after it was broken or detached from the card at some point after it was made, but before it came to the Museum. Conservators often call these remnants of glue a “glue scar.”

Clearly, this model was not Nr. 493 Lobiger picta, but what was it, and where was the real Lobiger picta?

What does Nr. 493 Lobiger picta really look like?

Figuring out what Lobiger picta actually looks like was a good place to start. A quick Google image search revealed a bright green animal with multiple appendages, confirming that the large dark green sea slug was not what it was thought to be.

Google search results for “Lobiger picta”.
Lobiger picta (without an original card) on view at The
Natural History Museum Vienna 1.

Further searching lead to an image of a Lobiger picta Blaschka model in the collection of the Natural History Museum Vienna. Another clue!

But the name on the label didn’t match; had the name changed or was this a different model? There’s one way to find out: according to the online World Register of Marine Species, Lobiger picta is no longer the accepted name. The currently accepted name is Lobiger viridis, just like the label states! But, alas, I can’t see the model clearly enough to find similarities with any of the hundreds of Blaschka models I had examined at the Museum so far.

The search continues

Past experience alerted me to the secrets held in the Blaschka archives, maybe I could find an image of the real model among the many drawings made by the Blaschkas held in the Rakow Research Library (and available online). I typed in “Lobiger picta”: no results. I tried the Blaschka catalog number on the label, 493. Success!

Blaschka drawing with model number 493. The Rakow Research Library (BIB ID 123011).
This unidentified Blaschka model of a green sea slug was
given its own loan number when it came to the Museum.
This means it was already separated and unidentified in 1963.

There, in the center of the page, is a green sea slug with 4 wing-like appendages that match the faint outlines on the card. But I still have not seen anything like it … or have I? Something about the shape of its head seemed familiar. Could it be the unidentified green sea slug back on the shelf?  

The missing elements

 A closer look at the unidentified slug revealed that it was missing elements on the sides. This could be it! Excitement built as I brought the model over to check how it fits on the card. The size and shape look right, what about the glue scar? A perfect match! This is Nr. 493 Lobiger picta!

Here is the unidentified model placed on the Lobiger picta card. The model fits perfectly on the original glue (placement is circled in green) proving these are a match.

While the model is not complete, at least now the real Nr. 493 Lobiger picta is identified and I know what else to look for. Many weeks later I found the 4 missing elements while organizing the last box of unidentified and broken glass bits.

The correct Lobiger picta model with all of its parts placed on its card.

On to the next challenge: identifying the large green sea slug

This time I had no name to work with, but I did have a stack of support cards that were no longer associated with a model. Since the Blaschka catalog grouped related species together, the catalog numbers of similar-looking models gave me a place to start and I quickly found a card that was the right shape and size.

Here is the large green sea slug with what I think is the correct card.

When the model became detached from its card, the surface of the paper remained stuck to the model in two places. These areas of paper match up perfectly to areas of surface damage on the card. The colored circles in the image above show the two matching pairs. With the glue scar matching perfectly, I now know the large green sea slug is Nr. 462 Miamira nobilis.

Another mystery solved!

When questions about an object arise, conservators look to the object itself for answers. Through careful examination, we find clues to the object’s origins and history that solve (at least some of) the mysteries it holds.


  1. https://www.nhm-wien.ac.at/en/press/__129#gallery-14

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Astrid van Giffen is the Museum's associate conservator. In 2007, she completed the conservation training program of the Netherlands Institute for Cultural Heritage (ICN) in Amsterdam, with a specialization in glass and ceramics. Her training included internships at the Walters Art Museum in Baltimore, Md, and The Corning Museum of Glass in Corning. Since completing the ICN program, she has worked as a private conservator in Oregon and was the Samuel H. Kress Fellow in Objects Conservation at the Straus Center for Conservation and Technical Studies of the Harvard Art Museum (2008-2009). She also holds a BA (2001) in Classical Studies from Willamette University.

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