Chemical & Dremel 290 prepping a partial ammonite

[SPrice]

Before I start, here's the disclaimer, caveat and warning : " Danger, Will Robinson, Danger! " .   Muriatic acid is harmful if used incorrectly.  There, I feel better now.

 

This particular partial ammonite is from the Late Cretaceous Period (Campanian) of the inland sea which was in southeastern Utah, where I collected it on BLM land.   I believe the species is Prionocyclus hyatti...or maybe Prionocyclus macombi. I struggle with these two ID's. 

 

So here it is.  Tools, prepping step by step and final assessment and finish.

 

Muriatic acid, toothbrush, gloves, a bowl of water, a rag, lots of outdoor ventilation.

 

 

Ammonite is back in water after millions of years of being underground.

 

 

Lets get sizzling! BTW- the acid is in a small jar just beside the red bowl. I dipped the toothbrush, then scrubbed and rinsed with the water in the bowl.

 

 

Scrub and rinse, repeat.

 

 

Getting into those nooks and crannies!

 

 

About 10 to 15 minutes into it.

 

 

   A little assessment to the progress and keep on brushing.

 

 

It's getting close to the look I want. However there are some areas much thicker in the tan skim of calcite so I will get to a point where I stop the acid bath, rinse it well and let it dry a spell.

 

 

I think this is it...time - 30 minutes of brushing and rinsing. Muriatic acid amount used -  1.5 ounces. 

 

Next step is to let it dry overnight and then glue the cracks.  I wanted the CA to wick deeply into the cracks so I used the really thin stuff. It's thinner that water...more like lighter fluid or gasoline. So I used a new tool from the utility belt - an insulin syringe. A bit tricky to load and remove the air without spilling or spraying any out through the needle. It flowed out quickly and needed the soft pressure while injecting it into the cracks.

 

 

 

 

I was very cautious with this technique. The plunger needed enough pressure to start the flow and a smooth mode to not go overboard. Also, I kept the orange safety cap on it while transporting it.  I gave myself the heebie-jeebies just thinking about carrying it without the safety cap on it and having an "Oops!" moment by dropping it, tripping on the stairs, and any other possible way to unintentionally inject myself with cyanoacrylate adhesive.  Took a minute to dispel those thoughts. 

 

Once that was done I brought the Dremel 290 engraver with the flat tip stylus installed to chisel away some areas that the acid struggled with removing.  That took about 20 minutes... no action pics. I was satisfied and gave it a dusting and damp wipe to clear off the dust, dried it in the hot Utah sun and was ready for the finishing treatment.

 

 On to the Paraloid coating.

 

 

 

The cell phone makes the coating appear much shinier than it is. There were some very slick spots on the ammonite and they did stand out with a gleam.  It's currently on the hearth standing with some other ammonites and a few slabs of petrified wood.  I'm pleased with the outcome, a few sutures were revealed and the partial reveal/partial matrix cover is appealing to me. 

 

On to the next one! 

 

Steve

 

 

 

Edited September 7 by SPrice
typos

[Shaun-DFW Fossils]

19 minutes ago, SPrice said:

Before I start, here's the disclaimer, caveat and warning : " Danger, Will Robinson, Danger! " .   Muriatic acid is harmful if used incorrectly.  There, I feel better now.

 

This particular partial ammonite is from the Late Cretaceous Period (Campanian) of the inland sea which was in southeastern Utah, where I collected it on BLM land.   I believe the species is Prionocyclus hyatti...or maybe Prionocyclus macombi. I struggle with these two ID's. 

 

So here it is.  Tools, prepping step by step and final assessment and finish.

 

Muriatic acid, toothbrush, gloves, a bowl of water, a rag, lots of outdoor ventilation.

 

 

Ammonite is back in water after millions of years of being underground.

 

 

Lets get sizzling! BTW- the acid is in a small jar just beside the red bowl. I dipped the toothbrush, then scrubbed and rinsed with the water in the bowl.

 

 

Scrub and rinse, repeat.

 

 

Getting into those nooks and crannies!

 

 

About 10 to 15 minutes into it.

 

 

   A little assessment to the progress and keep on brushing.

 

 

It's getting close to the look I want. However there are some areas much thicker in the tan skim of calcite so I will get to a point where I stop the acid bath, rinse it well and let it dry a spell.

 

 

I think this is it...time - 30 minutes of brushing and rinsing. Muriatic acid amount used -  1.5 ounces. 

 

Next step is to let it dry overnight and then glue the cracks.  I wanted the CA to wick deeply into the cracks so I used the really thin stuff. It's thinner that water...more like lighter fluid or gasoline. So I used a new tool from the utility belt - an insulin syringe. A bit tricky to load and remove the air without spilling or spraying any out through the needle. It flowed out quickly and needed the soft pressure while injecting it into the cracks.

 

 

 

 

I was very cautious with this technique. The plunger needed enough pressure to start the flow and a smooth mode to not go overboard. Also, I kept the orange safety cap on it while transporting it.  I gave myself the heebie-jeebies just thinking about carrying it without the safety cap on it and having an "Oops!" moment by dropping it, tripping on the stairs, and any other possible way to unintentionally inject myself with cyanoacrylate adhesive.  Took a minute to dispel those thoughts. 

 

Once that was done I brought the Dremel 290 engraver with the flat tip stylus installed to chisel away some areas that the acid struggled with removing.  That took about 20 minutes... no action pics. I was satisfied and gave it a dusting and damp wipe to clear off the dust, dried it in the hot Utah sun and was ready for the finishing treatment.

 

 On to the Paraloid coating.

 

 

 

The cell phone makes the coating appear much shinier than it is. There were some very slick spots on the ammonite and they did stand out with a gleam.  It's currently on the hearth standing with some other ammonites and a few slabs of petrified wood.  I'm pleased with the outcome, a few sutures were revealed and the partial reveal/partial matrix cover is appealing to me. 

 

On to the next one! 

 

Steve

 

 

 

Thanks for demonstrating a different way to do things relative to what I’ve learned so far. I’ve had good success with 10-second dips in a 50/50 water+muriatic acid mix but I’ll definitely keep the brushing in mind as a possibility! I’m guessing the density and composition of the fossil greatly determines whether or not you use this method?

[Kohler Palaeontology]

Very nice.  However, would you worry about the acid dissolving the shell, or does that just apply to vinegar?

[SPrice]

4 minutes ago, Shaun-DFW Fossils said:

Thanks for demonstrating a different way to do things relative to what I’ve learned so far. I’ve had good success with 10-second dips in a 50/50 water+muriatic acid mix but I’ll definitely keep the brushing in mind as a possibility! I’m guessing the density and composition of the fossil greatly determines whether or not you use this method?

Hey Shaun, I experimented on some broken pieces of fossils in this type of matrix and obviously, too long submerging it ...dissolved more than wanted.  Also, just putting a little on the area I wanted prepped only went so far. The toothbrushing seems to revive the acid by pushing around the acid which kind of quit working...if that makes sense. The agitation just made it work longer.  Then rinse and repeat to get where you want it to be. Not what I would do for thick calcite coatings or to remove lots of matrix. These ammonites in concretions are often exposed and develop the thin skin of calcite on them that needs to come off. This is what I found to work. My acid solution is 100% out of the container. It will burn skin...even the tiniest drop will let you know...so I brush very slowing to keep the bristles from slinging micro droplets airborne. 

[SPrice]

Just now, Kohler Palaeontology said:

Very nice.  However, would you worry about the acid dissolving the shell, or does that just apply to vinegar?

 Thanks! I think most of the shell is gone on these ammonites. Once in a while I see nice remnants of shell.  It's quite obvious in the texture. It's smooth, flaky and brittle with a coating of "brown sugar" calcite granules under it.  Very fragile. It flakes off easily and if even present might be stuck to either the fossil or the imprint when the matrix is removed.  Short version - a lack of a quality preservation. These also break into a 3D rock puzzle if stared at too hard.

 

I also collect seashells on my beach trips and will give them a brief acid bath to revive the colors by removing the bleached white layer.  

[Kohler Palaeontology]

"I also collect seashells on my beach trips and will give them a brief acid bath to revive the colors by removing the bleached white layer."   That might be a good idea actually, would vinegar work on that?

[SPrice]

Oh and the acid fizzes and dissolves the lighter colored calcite coating and barely reacts in contact with the brown fossil minerals. The acid is applied with the toothbrush and is moved around quickly for 15-20 seconds, then rinsed.  Lots of rinse and repeat steps. 

[SPrice]

For those who collect seashells and want them looking great...this video.  

 

 

[Kohler Palaeontology]

Wow, that method works really well, thanks!

[SPrice]

Bed time on my side of the planet and the fish will be calling at dawn tomorrow. 

[Ludwigia]

Very good results with that method on this type of fossilization. Did you also use soapy water (or some kind of base) to neutralize the acid when soaking or was plain water good enough to remove all the residue?

[SPrice]

Hi Roger, just a water rinse does it. Baking soda could also be used...but then another washing to remove that residue. 

[DPS Ammonite]

12 hours ago, Ludwigia said:

Very good results with that method on this type of fossilization. Did you also use soapy water (or some kind of base) to neutralize the acid when soaking or was plain water good enough to remove all the residue?

You also can add a piece of calcite or limestone which can be collected for free.