Ultrasonic Cleaning of Fossils

Late last year I bought an ultrasonic cleaner from a seller on Amazon.com. One of the uses for it was to clean fossils. After trying it out on coins and jewelry, I did not much difference in the before and after and shelved it. I think some of my issues though were in my process and the items I was trying to clean.

So this weekend I tried another coin and it seemed to clean it up quite a bit. The change (so to speak) I made in the process was using distilled water and heating it before hand in the microwave till it was coffee hot. I then added about 4-8 drops of Dawn dish cleaner to the water. Set the cycle to 480 seconds. Once complete, removed the basket and rinsed the specimen in tap water. Then brushed it with soft bristle tooth brush. Put the specimen back in the cleaner for another 480 seconds. Repeated this process until it seemed cleaner than before I started.

Above you can see the Devonian Period fossils I started with. A couple branching corals, button coral, and some crinoid holdfast stems.One can then observe what they looked like after I finished. The water was quite muddy looking at the end of the process. While not perfect, it was definitely an improvement.

Below is a link to the cleaner I was using. If you are interested make sure you read a sampling of the comments as they are a mix of works great to does not work at all. I experienced both cases of this and I think it depends on what you are trying to clean and the process you pick for the workflow of cleaning. I have since cleaned a number of brachiopod and blastoid fossils with good success.

Magnasonic Professional Ultrasonic Jewelry Cleaner with Digital Timer for Eyeglasses, Rings, Coins (MGUC500)

I am also experimenting with small Bissell steam cleaner though I need a way to hold the fossil in place while cleaning with this. Inspiration for this came after watch the BBC show The Repair Shop on Netflix. They use a wand like steam cleaner on ceramic items with amazing results. This type of device is especially good at getting dirty out of crevices and cracks. If I get good results using it on fossils I will make a posting about it.

Cheirurus niagarensis Trilobite Fragment

Previously images of an unprepped Cheirurus niagarensis trilobite pygidium was shown (see this post).  Recently, the fossil was cleaned using a sand abrasion technique.  These pictures show the results. First image fossil is photographed wet to enhance contrast. Fossil was found in the Waldron Shale of Clark County, Indiana, USA. It is dated to the Silurian Period.

The second shows a before and after cleaning images of the fossil. When cleaning I wear a respirator to keep silicate dust from getting to my lungs. Just looking at these images brings the memory of a smell of the rubber face piece. It is interesting how smells can get associated with tasks one does during the day.

Cleaning fossils takes patience and some strategy on how to approach the fossil to clean it. I was a little too ambitious on the top of this fossil thus wearing off the top thorax sections with the sand stream. Still it is nice to see more shape and detail of this fossil fragment. The Waldron Shale is easier to clean since it is soft and you can see immediate progress at removing it. During my cleaning session, I went through 3 canisters of sand while working on maybe 10 fossils before stopping. Thanks to Kenny for letting me use his cleaning equipment and help with removing matrix with an air scribe.

Fossil Prep Tools

Today's post is about fossil preparation. When I first started collecting fossils, I wondered how some of the museums got such nice trilobites. Who was finding these fossils intact like that with so much detail? After many field trips and considering myself luckily to find just a trilobite fragment, it dawned on me that these museum fossils were not found in that display state. As it turns out,there might have been just a small area showing of the fossil when it was found in rock matrix. It was the skill and patience of a determined preparer who coaxed the fossil form to appear from its stone tomb.  After that I realized that finding a good fossil is just the beginning, cleaning is where the work lies.

First off, we begin with safety. Everyone needs to wear safety eye protection when working with rocks. When using picks, knives, screw drivers, chisels, engravers and other tools pieces of rock can fly out and hit the user or observers in the eyes. So they must be protected! It is also possible the tool can break apart and pieces fly off.  Here is a pair of safety glasses I use.

The second piece of safety equipment I use is a 3M dust mask.  You need to wear one of these when using a Dremel brush to remove matrix from the fossils.  I also wear it when using the sand abrasion cleaner.  Even though it is in a box and under vacuum, it is best to take precautions to prevent breathing in any lime or dolomite dust.

Of course, when I put on the mask, I have to say some pseudo quote from the Star Wars movie like "Luke, I am your father" or "All too easy" after finishing cleaning a fossil.

This picture shows the Dremel engraver I use. It has 5 levels that allow adjustment to the force/frequency of this micro jack hammer. It has a modified tip on it.  An idea I got from a blog reader, Howard from Calgary, Canada.  He modifies metal rods to make fine engraver tips.

Here is the original tip that is useful for removing large sections of rock but somewhat cumbersome when trying to remove matrix from small crevices of the fossils.

 

The modified bit is actually an old engraving cutter (bit 105) from the Dremel drilling tool.  The small cutting ball wore off the bit just leaving a sharp point.  At the time, I could not think of a use for it but put it back in the Dremel toolbox. After obtaining the engraver and learning what Howard was doing with a sharper, fine pointed engraver bits, it gave me the idea to re-use this part.  As always wear safety glasses because the tip could snap off during use and hit something.

 

Here is the Dremel bit installed in the engraver. If I run into any micro-vampires, I am ready for action!

  

After removing larger pieces of matrix from the fossils, in my case Ordovician brachiopods.  I switch to the Dremel drill tool  This one has a stainless steel rotary brush installed.  At this point, in addition to safety glasses I put on the dust mask and use it out side to keep the dust out of the house.

 

Here is a picture of Dremel attachment 530, Stainless Steel Brush.

 

I was using the Carbide Steel Brush but it quickly lost its bristles after cleaning only 3 brachiopods.

 

I have another Dremel steel brush in a different configuration.

 

Once I finish brushing the specimen, I take an old toothbrush and dip it in diluted white vinegar  (acetic acid) and clean the fossil surface.  I then dip the fossil in water to clean of any dust and vinegar.  The specimen might still need to be air abrasive cleaned which takes me to my cousin's garage.

 

 The fossil then needs to be cleaned again with water and should be ready.  In the past, I tried to clean the fossils with just the air abrasive cleaner but it takes too long to clean large matrix areas.  So the method I use now is a multi-step procedure involving a combination of cleaning techniques.