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Superglues in Fossil Preparation

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What are superglues?

When you need a super-strong bond, there’s nothing that quite beats superglue! Superglues are technically known as cyanoacrylates, which are a group of quick bonding acrylic resins that can bond anything from plastic, to metal, to your favourite rocks and minerals. They use the humidity in the atmosphere to trigger a reaction that turns the liquid glue to a solid plastic mesh which holds surfaces together very tightly. The time this takes to happen depends on the viscosity (fluid thickness) of the glue and the thickness of the seam applied.

Using Superglues in Fossil Preparation

Superglues can be a little contentious in fossil preparation as they are usually considered irreversible (unless you have debonder). 

You might have read ‘DO NOT USE SUPERGLUE ON FOSSILS! IT IS PERMANENT!”. This can be a great thing, or a terrible thing...

Most of the literature (online and off) refers to a scientific approach to fossil preparation, performed in museums and laboratories where, for the sake of conservation, a permanent fix is not desirable and only the least invasive, most easily reversible materials should be used.

However, in the world of commercial, amateur and hobby fossil prep and private collections, there are fewer ‘rules’ so to speak. The style of prep is very different, often heavily focused upon aesthetic value as well as interest in prehistoric lifeforms. There is nothing wrong with this – fossil preparation in the commercial and amateur communities has become a true artform – just head over to Instagram to see what incredible things people can achieve. 

In the world of do-it-yourself fossil preparation, especially on fossils that will never end up in a museum (most of them don’t want the 100 Promicroceras ammonites you found last winter!), you might choose to use supergluebecause it is permanent, not in spite of this! It is incredibly strong, waterproof, versatile and brilliant for so many jobs.

It is often worth having a range of superglues to fulfil a variety of roles in fossil preparation. Excellent quality superglue will provide you with an industrial-strength bond that will provide a permanent solution. The ZOIC PalaeoTech range of superglues comprises a variety of viscosities, each with their own purpose. So in what situations might you use each of them?

Different viscosities (thicknesses) of superglue for different jobs

Low Viscosity

A very low viscosity cyanoacrylate is perfectly suited to consolidating and stabilising fossils. It can be used for ‘wicking’, which is the process by which it uses capillary action to pull itself into really small spaces. This is great for deep penetration into cracks and pores. It can also be used to drop gently onto thin, flaky material during the process of fossil preparation to hold it in place whilst using tools such as air pens which vibrate and have an air exhaust. 

It is ideal for use when joining extremely closely fitting parts and smooth, even surfaces (some minerals and crystals; as well as rocks that undergo conchoidal fracture like chert or flint have extremely smooth surfaces). It can also be used as a full consolidant, soaking into a slab of rock to stabilise it (it can stabilise shales, chalks, sandstones and other porous rocks).

Although there are numerous different approaches on how to prevent pyrite decay, some people use low viscosity cyanoacrylate to seal a fossil from the atmosphere via pore fill to prevent further oxidation and therefore pyrite decay. Low viscosity glues dry extremely quickly, in a matter of seconds. 

This fossil bone is extremely dry and very porous, with numerous hairline fractures. Low viscosity superglue can be used to seep through the bone to consolidate it permanently. 

Medium Viscosity

This what most people think of when they think ‘superglue’! It’s a great all-rounder with industrial-strength rock adhesion. It is used for structural bonding where joins need to be made. It can be used on smooth surfaces, as well as more porous and absorbent matrices. It is capable of filling small gaps and pores along the join. It can be used to penetrate narrow gaps or bond closely fitted parts. For most people, it is usually the most reached for and utilised! It sets almost instantly. Just hold the rock tightly together for a few seconds and set down or clamp to cure.

High Viscosity

A high viscosity cyanoacrylate is particularly helpful when you want a little bit more working time to align pieces and want to better control where the glue goes (lower viscosities spread very easily). High viscosity cyanoacrylate is rapid setting but has a slightly slower set time than the medium and low viscosities, which allows you a few more seconds to align the joint. This glue will fill wider cracks, holes and pores where necessary, and is very suitable for joining porous matrices as it is less likely to soak into them and will spread more evenly on top of the surface for bonding.

Extra thick Gel 

Our cyanoacrylate gel comes in a tube for controlled application. It is very thick for precise application and will not run or drip even when gluing a vertical surface. It also dries more slowly than the others in the range of cyanoacrylates and so gives more time to align and set all of the pieces together correctly (approx. 1 minute). The bond can then be prised apart if needs be for about 2-3 minutes and full set is approximately 10 minutes depending upon the depth of joint and thickness of glue. Full cure in 24 hours. 

Gel is extremely useful for gap and void filling, and can be used in conjunction with other viscosities to achieve this (e.g. first use low viscosity for its wicking properties, followed by the gel for bulk). Highly suited to long-lasting repairs and for bonding exceptionally porous surfaces (more difficult to bond with lower viscosities). The initial set time depends on the thickness of the glue used. The tapered applicator on our tube allows you to apply just the right amount in just the right place.

Application of gel superglue to a nodule in regular blobs. These blobs will spread out when the rock is brought together, but will not dry until this is done giving plenty of working time to get them in just the right place!

Using superglues in fossil prep - a few hints and tricks!

You’ve probably used superglue a few hundred or more times throughout your life, but here are a few helpful tips to get the most out of it.

  • Apply in blobs to one side of whatever you’re gluing and don’t spread them out. Use the joining of the two pieces together to spread the glue – it will give you a few more crucial seconds to get the alignment right. Once it is thin enough, it will set instantaneously.
  • Applying a thick seam of glue allows you more time to adjust and a thinner seam will set more quickly. A thicker seam cures more slowly and polymerization may not fully occur to the middle of the blob if it is too thick.
  • Alternatively, to get a quicker setting time than you would expect, use an activator! This catalyses the drying reaction.
  • If you need to block where the glue goes, paste a little wax on where you don’t want it.
  • Make sure the surface you are gluing is dry and free from dust, oil and grease. Too much moisture might cause a slight bloom.
  • That said, there are a few exceptions to the rule. With particularly dry fossils, such as some unconsolidated vertebrate material, it might be worth licking one surface and putting the glue on the other and then joining. This will speed up the bonding time and the extra bloom that might occur doesn’t matter if it won’t ever be seen.
  • Do not touch the top of the superglue bottle to whatever you’re working on, it will encourage it to clog.
  • Keep your glue in a cold environment away from sunlight to ensure longevity.
  • Wear safety glasses and a respiratory mask when using cyanoacrylates, especially if working on a larger project. 
  • In modelling, a lot of people use sodium bicarbonate or baking soda to help bulk out the superglue as a fast-drying gap filler that has the same strong bonding properties of the superglue alone. Please note that this reaction is exothermic and produces toxic fumes. Please wear a vapour-rated mask or respirator and work in a well-ventilated environment!

Other things to use with Superglue:

Debonder

Because sh*t happens! If you, like us can’t stand the feeling of superglue on your hands or often attach yourself to things, debonder is brilliant! You can also use it to dissolve bonds (even those that have sat around untouched for many years!). If something is misaligned or is set in the wrong place simply apply debonder to the bond line to penetrate for about 60-120 seconds. Removal may take repeated applications. Scrape away the softened glue and clean the surface of the rock or fossil with isopropyl alcohol and wash hands thoroughly with soap and water after use. Never use debonder anywhere near the eyes or mouth.

We carry two varieties in our range, one liquid, great for penetrating cracks, and a thixotropic version. This appears to be solid until vigourously shaken when it turns into a gel. This means you can control where you apply it very well!

Activator

Whilst the slowed setting time of higher viscosity glues can be exceptionally useful, sometimes once you’ve got your pieces into place you just want them to set. By spraying on a little activator, you can accelerate the curing reaction to set the bond in place instantly. Most activators are associated with a yellow-staining. We use a very low staining formula for this very reason, but we would still recommend you test first before use on pale coloured fossils or rocks.

It is important to understand the difference between scientific fossil preparation, performed by museums and laboratories and commercial or display preparation (performed by commercial fossil preparators and dealers, as well as many thousands of people around the world in their garden sheds).

When you might NOT use superglue

There may also be situations where it is better to use something like Paraloid B-72 (an acrylic resin). If you’re gluing together a 3D piece that comprises of 100s of shards that need to go in in exactly the right order – Paraloid may be your go to as mistakes happen and it is very easy to remove. Whilst debonder helps you remove superglue, it’s not recommended as an easy approach.

If you’re working on something of extraordinary scientific value, even if you don’t intend to sell it or donate it to a museum, it might be worth prepping it using conservation-grade materials for the sake of posterity – it may end up in the hands of research someday. 

Superglue is not typically the most flexible of adhesives, but can be one of the strongest. Paraloid B72 is praised for its flexibility and so if your fossil may require some level of flexing it might be best to avoid superglue. 

A further reason one might wish to use Paraloid is if you have something that is likely to be dropped! A join with Paraloid will usually break along the same join, but if you drop something with superglue, more often than not it will find a new place to break as the bond is so strong. 


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