What is best Acetic dilution for fish teeth?

[Arizona Chris]

I have some Limestones full of fossil including fish teeth.  Traveling all over our small home town to find the strongest "vinegar" I could, and first I saw a gallon at the supermarket was 5%.  Pickling vinegar at Walmart - 5%.  Cleaning vinegar at Home depot - 6%.  They advertise on their web site 30% called "Ultra Vinegar" but no one in the store has a clue.  Ive heard that 10% is what is used on the Gogo stuff.  Please give me your thoughts, thanks!

[jpc]

5% should do the trick.  Of course it all depends on the rock your teeth are in.  t is a very slow process.  stronger acid is not necessarily better cuz it bubbles more violently and breaks up all the little fossils you are trying to liberate.

[FossilDAWG]

5% should be adequate.  Be sure to try it on a "less valuable" piece first to make sure the acid does not etch the teeth as well.  Researchers will sometimes use a phosphate buffer with the acid to reduce the chance that phosphate from the teeth will be solublized, but that is not always necessary.

 

Don

[Arizona Chris]

Thanks!  I found a locality with a very pure limestone in the Permian that has a large number of silicifed fossils that are very small in size.  Ill try that first, and if nothing shows up, the Naco limestone has sharks teeth for sure in it.  

 

 

[FossilDAWG]

If the fossils are very thoroughly silicified you may be able to get away with something stronger/faster.  I have been treating some Ordovician limestone with hydrochloric acid to release very finely preserved trilobite sclerites.  One of the early papers on these fossils specifically stated that they could withstand treatment with very concentrated acid, so they used as high a concentration as they could without having the acid bubble out of the container!  I've been buying commercial muriatic acid (a commercial name for hydrochloric acid) from Home Depot or Lowes and using it diluted 1:1 with water.  However other fossils I have cleaned with acid in the past would have been destroyed by such vigorous bubbling, so test it out first before taking the plunge with something you can't replace.

 

Don

[Doctor Mud]

5 hours ago, Arizona Chris said:

I have some Limestones full of fossil including fish teeth.  Traveling all over our small home town to find the strongest "vinegar" I could, and first I saw a gallon at the supermarket was 5%.  Pickling vinegar at Walmart - 5%.  Cleaning vinegar at Home depot - 6%.  They advertise on their web site 30% called "Ultra Vinegar" but no one in the store has a clue.  Ive heard that 10% is what is used on the Gogo stuff.  Please give me your thoughts, thanks!

Hi there,

 

The most important thing to consider is the pH of the acid you will use and whether or not you should buffer the solution. pH can be tested with a meter (accurate) or pH strips (less accurate).

 

Here is a useful thread from earlier in the forum. It contains some useful papers on using acid to extract teeth and instructions for testing pH and making a buffered solution if it is needed.

 

 

Good luck and please show us your results.

[Arizona Chris]

Thanks, its slowly becoming clear to me.   I tried muriatic once, and the fish teeth and bones all turned to charcoal!  I also want to see if there are any conodonts.  HCl is not good for them either I hear...

[Doctor Mud]

3 hours ago, Arizona Chris said:

Thanks, its slowly becoming clear to me.   I tried muriatic once, and the fish teeth and bones all turned to charcoal!  I also want to see if there are any conodonts.  HCl is not good for them either I hear...

I had a bad experience with acetic acid.

The concentration of teeth in the rock was very high- a good problem to have!

The calcerous matrix initially acted as a buffer for the teeth. But after changing the acetic acid it started attacking the teeth! 

 

I ended up getting a pH meter and doing some experiments with spare teeth to see which pH would be best. You want it low enough to dissolve matrix, but not too low to dissolve the teeth. A buffered acetic acid solution may also be advisable a X this is made by dissolving spare matrix, or leftover acid from previous rounds of dissolution.