Air scribe preparation possible mistakes

[Dimitris]

Hello friends!

I am experimenting this period with my new Haufwerk W224 air scribe.

It is recommended as ideal for beginners and rated for medium to fine preparation.

 

My first lab rat turned out above my expectation. First attempt was done without press. regulator and without filter, since I did not know I needed these.

Lab rate Prior preparation and After.

Soft limestone for your reference.

 

After having finished the above and onwards I work with pressure regulator (never above 5bar~70psi) and water separating filter to ensure I am using dry air.

 

The next one turned out really bad. One side was already exposed 100% due to weather erosion. The other side was fully covered except the edge. The beginning seemed promising.

The first material was removed around 2 o'clock and started chipping away easily. After that I lost my path completely. I couldn't define what is material to remove and what is ammonite.

The stone is quite hard limestone from the Jurassic of Bulgaria, Ammonitico Rosso.

I believe that with air abrasion with hard material the result would be totally different, but I do not have yet this set up.

[Dimitris]

Next one is a rare (because the outcrop does not exist any more) Triassic ammonite from Greece.

This is a sample with great sentimental value for me, so I stopped at the point I felt I will do damage rather than preparation.

The material is softer than the Jurassic above, limestone again. The fossil was completely covered under matrix, except the centre of the ammonite.

I will touch it again soon as I have your advice.

Like before, I believe that any further finishing would be successful with air abrasion. 

[Dimitris]

Last on the list, a big middle Jurassic or Late Jurassic 20-22cm.  

Here the covering matrix is quite soft, marl I think. Possibly there is a percentage of iron oxides (judging from the brown/black colour and some inclusions found). At some points of preparation, I could smell an odour similar to sulphur.

Here the size of the fossil helped a lot. The matrix was chipping away much easier, even at lower pressure (3-4bar). 

On the third picture I think I lost my path again. The fossil has quite good preservation, even parts of the outer shell are visible.

I broke it into two pieces due to bad extraction.

Here you can see pictures how it was found last year.

http://www.thefossilforum.com/uploads/monthly_2020_05/4.jpg.5829165670c3a256b234d38dc4156f43.jpg

http://www.thefossilforum.com/uploads/monthly_2020_05/2.jpg.be1943f5b6be9cac6919fc1ed3e6f7a3.jpg

http://www.thefossilforum.com/uploads/monthly_2020_05/3.jpg.b67b11e450f0bba8dd9f111be382fe4c.jpg

 

I spent a couple of hours seeing videos of preparation with air scribes on youtube, yet I do not understand what I am doing wrong.

I would really appreciate a piece of advice, as at this point I am very disappointed with the outcome.

I clearly accept the fact that I am newbie and mistakes are normal, yet I need to learn from them.

PS> Don't mind the rudist, it is just assisting the ammo standing!

[Thecosmilia Trichitoma]

@RJB  @Ptychodus04   @steelhead9   

 

These expert preppers might be able to help. (sorry if I forgot any others. Our forum has a LOT of them.)

[Ptychodus04]

Often, there is little to no separation layer between matrix and fossil on ammonites. This is caused when the shell is actually dissolved and the steinkern is in contact with the matrix. I think this is what you have going on. @Ludwigia is well versed in prepping ammonites of a similar age from Germany. I know he employs abrasive to remove the final bits of matrix. Do you have magnification? I prep with a minimum of 5X on all fossils. This helps you to see where the matrix ends and the fossil begins. Otherwise, the scribe will cut through before you see it.

[Dimitris]

12 minutes ago, Ptychodus04 said:

Often, there is little to no separation layer between matrix and fossil on ammonites. This is caused when the shell is actually dissolved and the steinkern is in contact with the matrix. I think this is what you have going on.

 

Thank you! Maybe this is indeed the case with the 1st and last ammonite. For some minutes maybe an hour, I was progressing slowly but precisely removing matrix.

Then I was digging and digging without stop. I flip the ammo vertically only to find out that I was actually damaging the fossil.

12 minutes ago, Ptychodus04 said:

@Ludwigia is well versed in prepping ammonites of a similar age from Germany. I know he employs abrasive to remove the final bits of matrix.

Nice thought, yes Roger might be able to help. Especially concerning the Triassic Hallstatt type ammonite.

12 minutes ago, Ptychodus04 said:

Do you have magnification? I prep with a minimum of 5X on all fossils. This helps you to see where the matrix ends and the fossil begins. Otherwise, the scribe will cut through before you see it.

I plead guilty no, though I intend to buy.

In addition, I must upgrade my glasses since both myopia on my left and astigmatism on the right have increased slightly. I can tell the difference when using my office glasses vs home.

Would you suggest a head mounted magnification kit or a stable one?

[jpc]

I have to agree with everything Ptych said.  Magnification is a MUST for this stuff.  

[Dimitris]

I think a head mounted would not be possible since I wear glasses when working.

Something like this would be good? Offers 5X, there are variations with even 1m arm and has extra led lighting.

The price of these is affordable 50-80$, then there is a big price gap until you find medical equipment with prices ranging above 600.

Do I need to put my hand so deep in the pocket?

 

[Ludwigia]

@Dimitris I would say that the sooner you get yourself an air abrader, the better things will get. If you are in doubt as to where the matrix ends and the shell begins while using the air scribe, then the best thing is to stop right away and switch over to the abrader. Start abrading where you know the shell is and then abrade further along following the shell to the point(s) in question. Sometimes there isn't even any shell to be found at those points, so you have to work around them with the abrader. Once you've found your orientation again, then you can switch back to the scribe. The best thing is to leave a thin layer of matrix above the shell which you can then remove with the abrader unless, of course, some matrix has already sprung away right at the shell. Also, a good knowledge of the structure and sculpture of the ammonite you are working on helps you know what to expect.

[Dimitris]

Thank you Roger, I really appreciate your suggestion. I am already onto this. Next to my store is a dentist who makes artificial teeth. After becoming familiar with some preparation sounds, I asked him and he showed me his equipment. I understood that the majority of our equipment originate from medical equipment. Found a kit similar to Vaniman for 250-270e which I will get soon. 

 

I am so glad I stopped prepping/damaging the triassic one before it way too late. 

 

So, to sum some things up

1. Magnifying plus proper lightning 

2. Air abrasion with all safety equipment for the lungs including 5μm filter for super tiny particles. 

 

Air scribe for bulk removal, abrasion for the detailing and uncertain areas. 

 

Any comments on the magnifying light I posted above? If I forget/omit something please let me know. 

Thanks a million for your help, I promise it will bear results! 

[Kiros]

Rosso Ammonitico is composed of nodular carbonate, it was sedimented close to aragonite compensation level, for this motivation the shell of ammonites are often partially dissolved and they are fused with the matrix.