How does a fragile eroded rock turn into a scientific fossil specimen? Fossil preparation - the processes carried out to make fossils useful for research and exhibition, either mechanical or chemical extraction of surrounding matrix, shapes how fossils are studied and interpreted.
So to understand how paleontology is done, we must understand the roles of preparators and their work, but we are not gonna go in detail about this in the post, because we don’t want to bore you, the post is too long already, and all depends on each fossil, state of preservation, type of matrix, etc., etc. In example, fossil bones or plant fossils require a different preparation approach as fossil fish or trilobites, or in example even different trilobite species or similar species of trilobites from different locations (different sediment) require different techniques, etc., etc.
Techniques used by today’s preparators have changed little since 100 years ago. Nowadays however, there are a multitude of tools available specifically for preparing fossils and a wider range of adhesives (glues, apoxies, resins) and consolidants available.
While everyone talks about best or cheapest tools used to prepare fossils, what about the adhesives used in fossil preparation?
A short way to answer:
We’ll compare cheap airscribes vs. more expensive in another post.
To answer the question in a long way, we need to say there are many things that need to be considered before any preparation takes start. In example, if your fossil has any cracks in it, or if it is fragile, or if it sits on soft shale, it might need consolidation or stabilisation during prep - best done with Starbond EM02, which will penetrate the thinest cracks and porous matrix with a stronger bond as Paraloid. Do not try to brush matrix off with water nor use tools that would transfer too much vibrations to the specimen before stabilization.
The tools, adhesives, methodology and techniques are highly dependent on the properties of each fossil and the surrounding matrix. The wrong approach can lead to damage or destruction of the fossil. Even with the understanding of different techniques and properties of different fossils/matrix, preparation is often not without risk, takes time, experience and patience. Usually a sample experimentation on less good preserved examples might be in order, if you are not familiar with preservation/preparation of fossils from a certain site.
Tools used for preparation range from a simple dental pick, scalpel, steel and carbide needles to mini-jackhammers, a multitude of air-scribes and micro-sandblasters. Sometimes all it takes is a toothbrush and water. Be careful however, some fossils, i.e. plant fossils, are a mere carbon film which could disintegrate if scrubbed with a brush.
Needles to say, if we don’t have experience and suitable tools for preparation, the best option is to leave fossil unprepared or ask more experienced preparators for help. It would be a shame to over-prep a good preserved fossil specimen only to destroy it trying to clean it up.
Important to emhasize again, each fossil is preserved different, so each preparation is different, and each preparation normally done with a specific aim in mind e.g., identification, research, commerce or display. Proper preparation can show details that give scientific value to the fossil. Documentation of the process is important too.
It’s easy to destroy fossils with use of cheapest, or non-suitable adhesives. Some specimens will often need consolidation and gluing during prep, therefore you should be aware of the properties of the various adhesives, and have them on hand before beginning to work. It is important to be aware of that glues may need to be un-glued and consolidation may need to be loosened during prep. All depends what type of fossils you are working with, aim of the preparation, tools and techniques used. And also depends on preparators personal choice.
Some preparators prefer to use Paraloid or similar PVA beads dissolved in acetone to consolidate or glue fossil, other prefer water-based glues, both are easy to remove or un-glue fossil bones in example, but often a plastic film over surface of the fossil or un-glueing is not desirable and are a mess to use compared to cyanoacrylates. There is no universal adhesive to cover all types of fossil preparation or stabilisation, because each preparation is done with a specific aim in mind, different adhesives react different with different sediments, specimens range in size from a few milimeters to several meter long. It’s silly to suggest Paraloid B-72 to glue ammonites, trilobites or echinoids, just as it’s silly to suggest cyanoacrylate to glue fossils that need to be un-glued easily or need a stronger bond. Most cyanoacrylate-based glues have a weak bond with smooth surfaces and as such give easily to friction. In such cases two component resin adhesives are best used, etc., etc.
Cyanoacrylate as Starbond are easy to use, have a strong bond, quick bonding time (3-10 seconds, 1 second with accelerator), long coagulation time (bottle open with fill-cap easily lasts several months, or up to 2 years if stored properly), and there's no mixing required, just open and use - means no mess or stinking up your lab mixing paraloid B-72 and aceton (aceton evaporation). Precise application with fill-caps, no plastic film over the fossil. Easy to remove with sandblaster, debonder or acetone, but when prepping or glueing most fossils (like ammonites, crinoids, plants, small verts or trilobites) you simply don't have to worry about un-glueing... And cheap 56g reusable bottle compared to the price of any 3g super-market available super-glue!
Here the chemical safety Sheet of Starbond Glue like Em-02:
- Starbond EM-02 is used to infiltrate micro-cracks and pores through capillary action, stabilizes fragile parts, works best to glue split parts of matrix together without a visible crack and can also be used for glossy protective coating. It can be removed w/ sandblasting or acetone. It's watery-thin. This instant adhesive is commonly used to repair cracks and hairline fractures because of its ability to easily penetrate narrow spaces and because it's well suited for strengthening porous, fragile material.
- Starbond EM-40 has a little higher viscosity (just a little thicker instant adhesive as EM-02) and a stronger bond as EM-02, but best used in a similar way. Recommended to use with less porous matrix or in example to glue spines, split matrix parts together and fill tiny cracks, strengthen porous, fragile parts.
- Starbond EM-150 is a "multi-purpose" cyanoacrylate super glue that possesses an oil-like viscosity. Great glue to fill or bond narrow cracks, bond closely-fitted parts, fill small gaps... Similar to the thinner CAs and other Starbond CA adhesives, EM-150 glue is compatible with wood, metal, rubber, leather, ceramics, gemstones, rocks, minerals, carbon fiber, fiberglass, PVC and most plastic materials.
- Starbond EM-600 is a Heavy Medium CA glue is an ethyl cyanoacrylate super glue that possesses a syrup-like viscosity that gives users sustained control on each drop of glue. The "heavier" medium CA glue is used for bonding and repairing. Starbond EM-600 Heavy Medium CA glue is specially formulated to have an extended curing time that lengthens positioning time for more precise bonding. Depending on the material to be bonded and the volume of adhesive used, bonding time may reach up to one minute. In all such instances, Starbond Accelerator is recommended to speed up bonding time. Starbond EM-600 Heavy Medium CA glue is a popular adhesive for repairing cracked stones such as marble counter tops. Sanding may be required to obtain the desired finish. You could use these glue on: Wood, Metal, Rubber, Leather, Ceramics, Gemstones, Rocks & Minerals, Carbon Fiber, Fiberglass, PVC and Most Plastics
- Starbond EM-2000: "gap filler". This gel thick CA adhesive has a high viscosity that gives it strong bonding capabilities and allows easy filling of large cracks and gaps. Stronger and less flexible as super-glues available in your super-market. Each drop of Starbond EM-2000 remains stationary even when applied on downward sloping surfaces. It is specially formulated to have an extended curing time to lengthen positioning time for more precise bonding, therefore works great to glue parts of fossil together precisely. Starbond Accelerator is recommended to speed up bonding time.
if you are interested in some references...we suggest you:
The Conservation Unit.1992. Science for conservators
conservation science teaching series; vol.1: introduction to materials, vol.2: cleaning,
vol.3: adhesives and coatings.
Davidson, A.R. 2002. Preparation of Citipati osmolskae. Journal of Vertebrate Paleontology
vol. 22, supplement to number 3. p. 48A.
Davidson, A.R. 2003. Adhesives as liquids. Journal of Vertebrate Paleontology vol.23, supplement to number 3. p.44A.
Davidson, A.R. 2003. Preparation of a fossil dinosaur. American Institute of Conservation
of Historic and Artistic Works, Objects Specialty Group Postprints 10:49-61.
Davidson, A.R., Alderson, S., and M. Fox. 2006. Assembling an archival marking kit for paleontological specimens. Journal of Vertebrate Paleontology vol.26, supplement to number 3. p.56A. http://www.vertpaleo.org/education/documents /Davidson_et_al_2006.pdf
Elder, A., et al. 1997. Adhesives and consolidants in geological and paleontological applications; part one: introduction, guide, health and safety, definitions; part two: wall chart. Society for the Preservation of Natural History Collections. vol 1 leaflet 2.
Koob, S.P.,1986. The use of Paraloid B-72 as an adhesive: its application for archaeological
ceramics and other materials. Studies in Conservation vol.31, no.1. pp7-14. Kronthal, L.,
Bisulca C., and A.R. Davidson. 2005. The use of Conservare OH-100 for the
stabilization of particularly fragile dinosaur bone. Journal of Vertebrate Paleontology vol.
25, supplement to number 3. p.80A.