Transcript case study - PaleoPortal Fossil Preparation

The use of cyanoacrylates and Butvar
B-76 (polyvinyl butyral) on a specimen of
Shuvuuia deserti (IGM 100/977)
from Ukhaa Tolgod, Gobi Desert, Mongolia
Amy Davidson
Division of Paleontology, American Museum of Natural History
The use of cyanoacrylates and Butvar
B-76 (polyvinyl butyral) on a specimen of
Shuvuuia deserti (IGM 100/977)
from Ukhaa Tolgod, Gobi Desert, Mongolia
Specimen in preparation, 1994
BUTVAR
Trade Name: Butvar
Trade Name: Krazy Glue®
BUTVAR
Trade Name: Butvar
Grade: B-76
Chemical name: polyvinyl butyral
Manufacturer: Monsanto
Date of purchase: 1986
Trade Name: Krazy Glue®
Grade: 201 ethyl white cap (low viscosity)
Chemical name: cyanoacrylate
Manufacturer: Borden, Inc.
Date of purchase: 1994
SOLUTION ADHESIVE
(sets by evaporation of a solvent)
REACTION ADHESIVE
(sets by irreversible chemical reaction)
BUTVAR
Trade Name: Butvar
Grade: B-76
Chemical name: polyvinyl butyral
Manufacturer: Monsanto
Date of purchase: 1986
Trade Name: Krazy Glue®
Grade: 201 ethyl white cap (low viscosity)
Chemical name: cyanoacrylate
Manufacturer: Borden, Inc.
Date of purchase: 1994
SOLUTION ADHESIVE
(sets by evaporation of a solvent)
REACTION ADHESIVE
(sets by irreversible chemical reaction)
BUTVAR
Shallow, weak, resoluble
Trade Name: Butvar
Grade: B-76
Chemical name: polyvinyl butyral
Manufacturer: Monsanto
Date of purchase: 1986
Penetrates, strong, insoluble
Trade Name: Krazy Glue®
Grade: 201 ethyl white cap (low viscosity)
Chemical name: cyanoacrylate
Manufacturer: Borden, Inc.
Date of purchase: 1994
IGM 100/977 fifteen years ago
IGM 100/977 now
2,000 gallons (7,570 liters) of fuel
On the road from Ulaanbaatar, 1993
UKHAA TOLGOD
An oviraptorid in-situ
Typical Ukhaa Tolgod preservation
broken bone in cross-section
Bone is soft, porous and weak
Excavating ”Big Mama”
Plastic eyedropper for dispensing
Extraction impossible
without consolidation
Heavy consolidation with Butvar B-76 is essential
“Big Mama”
Oviraptorid in brooding
posture over nest of eggs
Prepared with
Butvar B-76
Two oviraptorids
juvenile protoceratopcians
Prepared with Butvar B-76
Photos Mick Ellison
140 lb. (63.5 kg) barrel
Date of purchase: 1986
Butvar B-76 has a long shelf life and is
a very stable material
Feller, R.L. et al. 2007. Photochemical deterioration of poly
(vinylbutyral) in the range of wavelengths from middle ultraviolet to
the visible. Polymer Degradation and Stability 92 (5): 920-931.
Butvar B-76 is soluble in a wide range of solvents
a more commonly available solvent
a rare bottle of lab grade ethanol
Butvar B-76 coatings are very easily re-dissolved and reworked
Butvar B-76 coatings are
weakly adhesive…
…and easy to peel off.
Matrix is consolidated yet easily removed
Butvar B-76 can be mixed with ground matrix to form a paste
Butvar B-76 and matrix pastes are strong yet easily reworked or removed
Butvar B-76 is a shallow but effective
surface consolidant
Saichangurvel davidsoni
• Heavy coatings can be reduced later
• Shallow, weak consolidation does not
interfere with preparation
• Butvar B-76 has an aesthetically
pleasing matte finish
Photo Mick Ellison
Return to Ukhaa Tolgod
1994
Specimen in-situ
Mononykus?
Casts and mount - Dennis Wilson and Marilyn Fox
Photo- Mick Ellison
Forelimb of Mononykus olecranus
?
The first complete skull ?
Heavy consolidation with Butvar B-76
Preparation from bottom
AMNH prep lab
1994
Preparation up toward consolidated surface…
Preparation halted
Fibers associated with bones
Feathers
Fibers- no adhesive present
SEM images show
similar structure
Isolated fibers embedded in LR White acrylic and thin-sectioned
• Digestion with cellulase –
not plant or fungus
• Transmission electron microscopyhollow structure
• Time of flight secondary ion mass spectroscopy –
original molecules present
• Immunohistological studies-
beta-keratin in fibers is comparable
to beta-keratin in feathers
Schweitzer,M.H. et al. 1999. Betakeratin specific immunological reactivity
in feather-like structures of the
Cretaceous alvarezsaurid, Shuvuuia
deserti. Journal of Experimental
Zoology (Mol Dev Evol) 285:146-157.
Direct evidence that IGM 100/977 was covered with feathers
Skull separated from postcrania
for continued preparation
Why cyanoacrylates?
Cyanoacrylates are effective micro-consolidants- can wick into tiny cracks and pores
Cyanoacrylates form extremely thin, hard coatings
Cyanoacrylate coatings are insoluble but can be softened and removed on a tiny scale
The tiny teeth of IGM 100/977
Cyanoacrylates can be applied in extremely tiny drops
Krazy Glue® Type 201 Ethyl White Cap™
Date of purchase: 1994
Aron Alpha ® Industrial Krazy Glue Type 201
Date of Purchase: 2009
How will they age?
Down, J.L. and E. Kaminska. 2006. A preliminary study of the degradation of cyanoacrylate adhesives in the
presence and absence of fossil material. Journal of Vertebrate Paleontology 26 (3): 519-525.
How to make this strong enough to handle?
Reinforcement with Butvar B-76 and matrix
Cyanoacrylate and
fiberglass armature
Attaching a
removable armature
Butvar B-76 and matrix paste
over armature to build handle
before
after
First known skull for Alvarezsauridae,
used to describe the new taxon
Shuvuuia deserti
Chiappe et al. 1998. The skull of a relative of the
stem-group bird Mononykus. Nature 392: 275-277
Chiappe et al. 2002. The Cretaceous, short-armed
Alvarezsauridae: Mononykus and its kin. Pgs. 87120, In Chiappe and Witmer (eds.). Mesozoic Birds:
Above the Heads of Dinosaurs. Univ. of Cal. Press
Shuvuuia deserti
2000 Exhibition
Model by Dennis Wilson- Pangaea Design
Reconstruction
for
Exhibit
For exhibit
Reconstructed plaster jacket
Brazed brass armature
Filled with Butvar B-76 and
matrix paste
2000
Shuvuuia deserti on exhibit
Research and temporary storage
Research and temporary storage
Research and temporary storage
a cushioned “cavity mount” made without adhesives
Damage 2007
Future repairs and preparation
SOLUTION ADHESIVE
(sets by evaporation of a solvent)
REACTION ADHESIVE
(sets by irreversible chemical reaction)
BUTVAR
Shallow, weak, resoluble
Penetrates, strong, insoluble
Trade Name: Butvar
Grade: B-76
Chemical name: polyvinyl butyral
Manufacturer: Monsanto
Date of purchase: 1986
Trade Name: Krazy Glue®
Grade: 201 ethyl white cap (low viscosity)
Chemical name: cyanoacrylate
Manufacturer: Borden, Inc.
Date of purchase: 1994
The scientific value of this specimen
has depended and will depend on Butvar B-76
BUTVAR
Shallow, weak, resoluble
•
•
•
•
•
•
•
Strengthened enough for safe collecting from a remote locality
Did not impede gentle removal of matrix from fragile bone
Did not impede recognition, extraction and analysis of feather fibers
Strengthened fragile skull with matrix paste for extensive handling
Allowed reversible reconstruction for exhibit
Will not impede further preparation
Resistant to deterioration over time
The scientific value of this specimen
has depended and will depend on Krazy Glue®
BUTVAR
Penetrates, strong, insoluble
•
•
•
•
Strengthened fragile skull bones and teeth allows handling
Fiberglass armature inside handle allows handling
Small scale use will not impede further preparation
Probably resistant to significant deterioration in tiny amounts
as a consolidant/coating
Paraloid B-72
+
Consolidation:
Butvar B-98
(
Cyanoacrylates?
(
Joining:
+
Archival Housing
Paraloid B-72
for joining breaks
Housings reduce
shuffling and handling
Housings help adhesives
hold the specimen together
Future consolidation: Butvar B-98 if possible
cyanoacrylates if necessary