How to Choose an Air Pen (Air Scribe) for Fossil Preparation
Air pens or air scribes are the number one tool in fossil preparation. Essentially, an air scribe is a compressed air driven stylus or needle that repeatedly hits the rock many thousands of times per minute, removing matrix from your fossil. Air pens are the most ubiquitous type of fossil prep tool there is, found in garden sheds up and down the country all the way through to museum and professional prep labs. For a beginner, the natural progression up from an electric engraver or hand tools is an air pen before diversifying into multiple air pens and air abrasives
There are a few things to consider when purchasing an air pen. What sort of fossils are you collecting? How fragile are they? Is there a lot of hard rock that you need to remove before working on the fossil? What’s your budget? Do you already have an air pen?
Different tools do different jobs, and have different internal mechanisms which make them exceptionally good at some jobs, but relatively poor at others. All of our air scribes at ZOIC PalaeoTech are custom designed to fulfil a need in fossil preparation, but we do our best to make them as versatile as possible to maximise their usefulness. Whilst there are ‘general purpose’ tools to suit somebody just getting started, many professionals or advanced vocational fossil preparators have a myriad of tools; each with its own very specific niche in their work.
ZOIC PalaeoTech have a PRO Range (including the T-Rex, the Maia, Velociraptor, Microraptor, Balaur and Bronto) as well as our budget offering, The Trilobite. It's important to match the air tool you have for the job in hand.
A good tool improves the way you work. A great tool improves the way you think.
Most fossil preparation follows a similar progression. Work typically begins with the removal of large amounts of surrounding rock and gradually moves toward more delicate work as the fossil becomes exposed.
A useful way to think about this process is as a spectrum:
Bulk Removal → Moderate Preparation → Fine Preparation → Ultra-Fine Detail
Early stages may involve removing large volumes of matrix quickly, while later stages require very careful work directly around fragile fossil surfaces. Because of this progression, many preparators eventually use several different tools, switching between them as the work moves closer to the fossil.
Power vs Precision in Fossil Preparation
It is worth understanding that different tools influence preparation in different ways.
Tools designed for bulk removal are primarily about speed. They allow large amounts of surrounding matrix to be removed quickly, which can significantly reduce the time required to reach the fossil. However, these tools rarely improve the final quality of preparation. Their role is simply to make the early stages of the work more efficient.
The quality of fossil preparation is usually determined during the later stages, when the preparator is working very close to the fossil surface. At this point, fine and ultra-fine tools become far more important. Precision tools allow small amounts of matrix to be removed in a controlled way, reducing the risk of damage and making it easier to reveal delicate details such as ornamentation, sutures, or bone surfaces. For this reason, many preparators find that while powerful tools can speed up their workflow, it is the finer tools that ultimately determine the quality of the finished specimen.
Ultimately, the skill of the preparator matters far more than the tool itself, but having the right tool for the stage of work can make that skill much easier to apply.
What fossils are you prepping?
The internal mechanism of an air pen will dictate how successful you are at your prep. There are two types of air pen - which one suits your needs? All air pens in fossil preparation are variations of two different internal mechanisms. A very basic understanding of these internal mechanisms will arm you with the knowledge you need to make an informed choice. Often having one or more of each type of tool up your sleeve gives you the most flexibility in your set-up, but sometimes budget allows the choice of only one - so it's important to make the right choice!
Fossil preparation air scribes categorise into two general types. Whilst you may not need to understand how each type works, it makes a big difference depending on what you will be preparing and your successes with such. We call these types Impact Driven and Pusher Plate Driven. We make both types so you know you have all bases covered.
Air pens fall into two broad mechanical categories; Impact-Drive and Pusher-Plate.
Both designs have advantages, and many preparators use a combination of both depending on the task at hand.
Impact-driven tools use a reciprocating piston that repeatedly strikes the tip. These tools typically deliver higher impact energy and are particularly effective for removing harder matrix. These are considerably more complex internally and therefore usually more expensive.
Powerful matrix removal
Less noisy at lower pressures
Better with more robust fossils
Faster matrix removal
More likely to induce matrix 'popping'
Pusher-plate tools use a different mechanism that produces a smoother motion. These tools often provide greater sensitivity and control, which can be advantageous when working very close to the fossil surface.
Perfect for detail and finishing work
Velociraptor (PRO Range) and Trilobite (Entry-Level) are all-rounders, suited to moderate matrix removal
Less vibration and more control on delicate fossils
Cheaper than impact-driven tools
Noiser (and higher pitched) than impact-driven tools
The ZOIC PalaeoTech Air Pen Range
The ZOIC PalaeoTech range is designed to cover the full spectrum of fossil preparation tasks, from heavy matrix removal through to extremely delicate work.
THE BRONTO
BULK MATRIX REMOVAL
The Bronto is designed for the earliest stages of preparation where large amounts of rock must be removed quickly. It delivers high impact energy and performs well on hard matrix or large nodules. Tools in this category are often used to expose the general shape of a fossil before switching to more precise tools. Can be fitted with 5mm styli.
- removing large volumes of matrix
- working on hard rock
- exposing large fossils
- not suitable for working close to the fossil
THE VELOCIRAPTOR
ALL-ROUNDER (SOFTER ROCKS)
The Velociraptor focuses on precision and control, but with a more power than the Microraptor. Tools in this category are often used when the fossil surface is becoming exposed and careful work is required to avoid damaging delicate structures.
- mixed preparation (moderate/fine)
- all-rounder where there isn't much overburden
THE T-ReX
THE WORKHORSE
The T-Rex is a powerful and versatile tool suited to bulk and general fossil preparation. It provides a balance of power and control, allowing preparators to remove matrix efficiently while still working reasonably close to the fossil. It is particularly effective when dealing with difficult matrices such as pyritic or “sticky” fossils. Can be fitted with 3mm styli.
- bulk to moderate preparation
- exposing large fossils
- suitable for processing harder matrices efficiently
THE MICRORAPTOR
FINE
The Microraptor is designed for extremely fine preparation.
It allows preparators to remove very small amounts of matrix at a time and is often used under magnification when exposing delicate features. Can be fitted with 1.5mm stylus.
- fine work
- not suited to matrix removal
- suitable for fine work with the 1.5mm stylus
THE MAIA
ULTIMATE ALL-ROUNDER
The Maia is designed to work across a broad range of preparation tasks. It bridges the gap between moderate matrix removal and finer work, making it useful for preparators who want a tool capable of handling both moderate removal and controlled preparation. Can be fitted with 3mm, 2.5mm, 2mm and 1.5mm styli.
- mixed preparation
- moderate matrix removal
- suitable for fine work with the 1.5mm stylus
THE BALAUR
ULTRAFINE
The Balaur is intended for the most delicate stages of fossil preparation.
It excels when working directly around fragile fossil surfaces or when revealing extremely fine details. It is much more advanced and versatile than the Microraptor. Can be fitted with 1.5mm, 1.3mm, 1mm and 0.5mm styli.
- ultrafine work
- suitable for microscope work
- finest stylus option on the planet (0.5mm)
THE TRILOBITE
BUDGET TOOL
The Trilobite provides an accessible introduction to pneumatic fossil preparation. It offers a solid starting point for hobbyists or beginners who wish to explore air-powered preparation tools before investing in more specialised equipment.
- general light preparations
- less investment when you're just starting out
- moderate to fine work
bUILDING YOUR FIRST SET-UP
An ideal set up is one with a variety of air pens, often at different ends of the power spectrum, with the user gradually building up their collection over time. While each tool can be useful on its own, many preparators find that having tools covering different parts of the preparation spectrum makes their work much easier.
Our most popular combinations are:
Bronto + T-Rex + Maia (bulk removal, hard rock)
Maia + Balaur (moderate removal, ultra fine prep)
Bronto + Maia + Balaur (bulk removal, moderate work, ultrafine prep)
T-Rex + Microraptor (hard rock, fine prep)
Velociraptor + Balaur (little overburden, fine prep)
Starting with a single tool
While having several tools can make preparation more efficient, many preparators begin with just one air pen. If you are starting with a single tool, it is often best to choose something that balances power and control rather than specialising at one extreme of the preparation spectrum. Versatile tools that can handle both moderate matrix removal and relatively fine work are often a good starting point (for most fossils, our best recommendation would be the Maia with a 2.5mm rounded chisel and 1.5mm point to cover the most bases).
As experience grows, some preparators choose to add additional tools that make specific stages of preparation easier or faster. This gradual approach allows a toolkit to develop naturally over time. If you are unsure which type of tool might suit your work best, it can be helpful to consider the types of fossils you prepare most often and the hardness of the surrounding matrix.
what to look for when choosing an air pen
When choosing, there are a few physical things to look out for in both new and second hand fossil preparation air pens or air scribes. A quality tool will last you many years (even decades) when looked after. These following bits of advice apply when choosing a new or a second hand tool – naturally a second hand tool will show wear and tear more obviously than a new one, but there are a few indications of how a tool might hold up over the years.
How well suited is the tool to fossil preparation?
The first major thing to think about is how appropriate the tool you're looking at is for fossil preparation. Bear in mind that not all air scribes are suitable for fossil preparation. Fossil preparation tools are typically designed specifically for that purpose, or modified from mass-produced pneumatic metal/plastic etchers and engravers.
If you see a metal engraver or air scribe for sale, don’t just assume that it will do the job just fine. Unfortunately some mass produced engravers are misleadingly marketed as fossil preparation tools when they are not fit for use.
Unmodified, or non-purpose built air scribes will likely have some things in common:
- Metal-working tungsten carbide. We use stone-grade tungsten carbide in all of our tools, which withstands the abrasive nature of rock for longer and requires less sharpening.
Unhardened or slightly hardened stylus bushing. Pneumatic engravers or air scribes for metal/plastic engraving don't require a hardened bushing, so they often don't have this. This means that after not much use, the stylus begins to wobble. Just because it's metal, doesn't mean that it won't wear over time. It needs to be properly treated for durability.
Short, stubby stylus. A longer, more slender stylus and supportive bushing are recommended for working with rocks.
The ergonomics, extended reach of stylus and enhanced resistance to wear and tear make a purpose-built fossil preparation air scribe a better choice. Fossil preparation is a demanding activity on any tool, and you need to be sure that you're investing in one that is up to the job.
A rundown of some popular air scribes or pneumatic engravers - do they have a place in the fossil preparation workshop?
You may have seen some of these for sale and been curious. We'll run through some of the characteristics of these mass-produced engravers to give you an idea of whether they might have a place in your workshop.
What may seem cheap, may end up costing you in terms of needing to replace a tool after very little use. Spares for these tools often aren't cheap, nor available in some cases. Many of these engravers (air scribes, air pens, air incisors) have extremely high air consumption, either meaning a very large compressor is required, or you will burn through compressors at a pace (all whilst clocking up a high electricity bill). There are many variables to consider, and fossil preparation is a very demanding activity.
Some of these tools are well made and very good at their intended application in their intended industries, but most are poorly suited to fossil prep. If you've somehow ended up here and you're just looking for information about various engravers you will find more helpful advice in forums and reviews from other people in your industry. These are not general reviews and whether an engraver is suitable for fossil cleaning or not does not have any reflection nor bearing on whether it is suited to its intended purpose. Chicago Pneumatic and Sealey in particular are market leaders for their air tools in their respective fields and applications with good reason.
Fossil Preparation Rating
The CP-9361 (Chicago Pneumatic)
The most famous pneumatic engraver of all is the CP-9361, which was almost ubiquitously used for fossil preparation until better, more appropriate tooling came along. As a metal/plastic engraver, it's brilliant.
Many preparators still choose to use an unmodified CP-9361, but a longer, more slender stylus and more supportive bushing are recommended for working with rocks. The ergonomics, extended reach of nib and enhanced resistance to wear and tear make a modified version a better option.
The internal workings are the real star in this tool. They are exceptionally durable and some have been going for 20+ years. We use the CP-9361 engraver as the base model of our ZOIC Chicago, utilising the power and durability of the internals, whilst making the external components suitable for fossil preparation.
We offer a modification kit to convert the CP-9361 into a ZOIC Chicago.
Our verdict:
It's OK for fossil preparation, but not ideal
Don't be lulled into thinking the CP-9361 Industrial Engraving Kit in the red box (as here) comes with a set of chisels. They are steel scalers and won't last any time at all for fossil prep.
Can be converted into a ZOIC Chicago with a modification kit if you find one going second hand at a good price
For just a little bit more money, you can purchase a brand new ZOIC Chicago that will last much longer, takes a point and a chisel and is better suited to fossil preparation.
Beware knock-offs, of which there are many.
Fossil Preparation Rating
The CP-9160 (Chicago Pneumatic)
The CP-9160 is a light-duty metal and plastic engraver designed as a cheap product for small, quick engraving jobs which it excels at.
It is unsuited to fossil preparation and doesn't tick many boxes in terms of comfort or demands on the air compressor.
It is extremely air hungry, using a whopping 1.69 CFM (nearly 50 litres per minute). To put this in perspective, this is almost 8x the consumption of our ZOIC Chicago. This means it requires a 1.5kW (2HP), 50l (13 gallon) air compressor minimum (much larger if silent). You run up your electricity bills no end, but you also risk burning out the compressor motor if your compressor is undersized or underpowered for the tool.
It is comparable in power to the Trilobite, but the Trilobite is more comfortable to use, significantly more durable, and costs only a bit more. It will stand the test of time for fossil preparation, where the CP-9160 will not.
Our verdict:
AVOID for fossil preparation. Don't be tempted by the low price.
- Very air hungry - you will need a hefty compressor to handle one of these.
Chicago Pneumatic designed this for short bursts of work, rather than the hours of fossil preparation we all want to be doing! The phrase 'light-duty' says it all.
No frontal exhaust.
Fossil Preparation Rating
Sealey SA96 Air Engraver
The Sealey SA96 is another light duty engraver designed for marking tools, components and security marking loan products. It is intended for perhaps a few minutes use at a time. For their intended application, they are well made tools at a good price.
For fossil preparation, it is a long way from what you need. It is very 'weak', with almost no power for matrix removal. It also doesn't have the delicacy required for very fine work.
It has an internal cylinder and piston, which means that it's an impact-driven tool, but lacks the power required to do the job. It is in fact less powerful than our Microraptor, which is also more appropriate for fine, detailed work as it imparts less vibration to the fossil.
The air consumption is an enormous 4 CFM at 60PSI (114 litres per minute at 4.1 Bar). We wouldn't run this tool continuously off anything short of a 100l, 2.2kW (26+ gallon, 3 HP) belt-driven air compressor. Electricity bills will be extremely high, for very little result.
Our verdict:
Avoid for fossil preparation. Will not last and doesn't do much for matrix removal. Needs a large, industrial compressor to run continuously.
A spare stylus will set you back almost as much as the tool again.
Too weak to remove matrix, too many vibrations to prep delicate fossils
Air consumption is through the roof - we wouldn't run this continuously on anything less than a 100l belt-driven air compressor. Would run fine on a smaller one, if only used for 1-2 minutes at a time as intended.
Fossil Preparation Rating
Generic (sometimes branded) pusher-plate Engravers
This one might look a little familiar! There are numerous mass-produced pusher plate engravers out there more or less replicating the ARO which was popular in fossil preparation many years ago, again before the advent of more advanced tools. The shape and the knurl are very distinctive so you should be able to spot one of these a mile off.
We actually use a better quality version of one of these tools as the base model for our Trilobite Air Pen, which is one reason we can make it so affordable! Ours has, however, been fully overhauled for fossil prep. These air scribes are made in many factories worldwide and many companies label them with their own branding. They do vary in quality from place to place quite considerably, but being pusher plate tools the room for error is less than with impact-driven tools.
However, once again we face the problem that they are not durable in fossil preparation. The stylus bushing (the 'nose' of the pen) is very rarely hardened in these unmodified versions, and metal can wear very quickly. This causes the stylus to increasingly wobble about with a sloppy fit, making any accuracy very difficult. They are also very noisy, air hungry (often around the 2CFM mark), and don't have a frontal exhaust meaning that the dust will sit on your work.
We've stripped the unmodified version of all the features that render it not durable and unsuitable for fossil preparation. The Trilobite is a much improved version. It is much quieter, has an optional and interchangeable frontal exhaust (and so is more flexible for work with fragile fossils and matrix removal) and a stylus bushing that means you won't see any wobble for years. We also reduce the air consumption and provide a better 'feel' for the work. Our Trilobite is fitted with stone-grade tungsten carbide, rather than the metal grade found in the unmodified versions.
Our verdict:
It's OK, but for only a bit extra you can purchase the Trilobite which is fully kitted out for fossil prep.
- Unmodified and/or lower quality versions won't last long. Spares are difficult to get.
- May be sold under a variety of brand names for a variety of applications.
- Air hungry. 2 CFM is demanding and will require a reasonably sized compressor for continuous use.
CHOOSING A SECOND HAND AIR PEN - SOME THINGS TO LOOK OUT FOR
Perhaps if you're looking at getting one of the above pneumatic metal/plastic engravers, maybe avoid. There are also things to watch out for in 'purpose-built' tools. Consider how much use the tool has had and how much life it might have left. Can you get hold of spares easily? Will you be able to get spares and have it serviced in the years to come?
One of the main things to watch out for and a sign of either poor build quality or a very very used tool (or usually both) is a wobbly stylus. The stylus should not wobble in the bushing – when this happens, more kinetic energy (power) is lost from side to side and not fully directed forwards. It is also harder to use a wobbly stylus as you can never be too sure where it is going to end up, on the rock or on the precious fossil!
If the bushing hasn't been sufficiently hardened during the manufacturing process, the stylus will develop a bit of personality. Our tools are all made to have a precision fit between stylus and bushing, so that maximum power is transmitted forwards and allows for maximum control. We harden and temper the metal (you can see that the bushings in the ZOIC Chicago, Microraptor, Velociraptor and the Trilobite are either a bluey or yellow colour – a side effect of this process - the T-Rex bushing is internal!), so that it will last you donkey’s years even with the heaviest use. Although side-to-side motions are not recommended for longevity of your tool, we understand that this is one of the easiest ways to smooth matrix. Our products are built to stand up to this movement for many years.
Another factor to pay attention to is air consumption. Not only does a lower air consumption mean that the tool is cheaper to run (running off a smaller, cheaper compressor, and allowing for the compressor to kick in less) but can also be an indication of manufacturing quality. Air consumption is dictated by the style of internal mechanism to a certain extent, but within a line up of comparable tools, the lowest air consumption for the internal mechanism means that there is less space within for air to be ‘wasted’ and escape. The tighter the engineering tolerances, the lower the air consumption. We pride ourselves in quality of workmanship and our range has the lowest average air consumption on the market. For example, the T-Rex, running at 5lpm (0.17 CFM) might only cycle a 50l compressor once every half an hour.
CONGRATULATIONS!
You've stuck with us this far! We very much hope that this guide has been helpful. It's important to understand some of the technicalities of how these tools work, in order to get them to work their best for you.
Fossil preparation is a varied process, and different stages require different levels of power and control.
Powerful tools can make the early stages of preparation faster, while finer tools provide the control needed to reveal delicate details safely. Many preparators find that working with tools that span the preparation spectrum makes their work both easier and more efficient.
Ultimately, however, the most important factor in fossil preparation is the care and skill of the preparator. Tools are simply there to support that process.