Help with preparing whole ammonite in matrix

[tjlyons123]

Hi everyone,

 

I've been a bit of a skulker on these forums so I will make my introduction brief and get to the pretty photos. I moved to New Mexico about 2 years ago and have been fossil hunting and rock hounding ever since. I've found some pretty awesome stuff, but this past weekend I really had my first major find, what I believe to be Coilopercas inflatum (see attached pictures). I have managed to get this specimen out of its surrounding matrix very nicely, and I would like to keep it whole and attached to the matrix base that it is currently on (the ammonite is actually detached from the matrix currently, but sits nicely in the fossil impression and my plan is to re-secure using cyanoacrylate gel once I have prepped the actual ammonite). 

 

My question is how should I deal with the white crust that is obscuring the ammonite structure? It is fairly soft, so I am wondering if a dilute acetic acid will take it off without damaging the underlying fossil. Secondly, how would one go about polishing this ammonite, and what varnish is typically used to keep it shining and protected from UV? 

 

Thanks for your help everyone! Really want to prep this one right!

 

 

[grandpa]

Please DON"T use acid.  It will likely etch the fossil as well as the white matrix.  Others will soon chime in to tell you how to proceed in a way that will not damage your ammonite.

[Ludwigia]

Like grandpa said, don't use any kind of acid on that! You have a calcite steinkern there. That white crust is the remains of the shell. First question: what kind of tools do you have available? Do you have an air abrader?

[tjlyons123]

17 minutes ago, Ludwigia said:

Like grandpa said, don't use any kind of acid on that! You have a calcite steinkern there. That white crust is the remains of the shell. First question: what kind of tools do you have available? Do you have an air abrader?

Hey folks, thanks for the quick responses! Currently, the only things available to me are hand tools (cold steel chisels, exacto blades, dental picks).

[Ludwigia]

58 minutes ago, tjlyons123 said:

Hey folks, thanks for the quick responses! Currently, the only things available to me are hand tools (cold steel chisels, exacto blades, dental picks).

Then I'd suggest removing the white crust by chipping away the edge of it with light taps bit by bit moving back very carefully with a small chisel. It should spring away from the steinkern. Once you've removed that you could scrub the steinkern carefully with a soft steel brush using a bit of soap under running water. I wouldn't necessarily try to polish it, which is somewhat complicated unless you have the proper equipment. I would rather apply a beeswax finish like Rember to it.

[Wrangellian]

2 hours ago, Ludwigia said:

 That white crust is the remains of the shell.

The outer shell of an ammonite gets so little respect!

[jpc]

That white stuff is the actual shell.  I would leave it as is.  But if you must, the others here have made good suggestions.

 

And as others have said...NO ACID.

 

[Ptychodus04]

1st, welcome to the forum.

 

2nd, shell preserved in this way is often very soft. Sometimes a stiff bristled grout brush will remove it. You can soften it with a bit of denatured alcohol. Nothing is needed to preserve the calcite steinkern. Otherwise, I would follow @Ludwigia's advice.

[tjlyons123]

6 hours ago, Ptychodus04 said:

1st, welcome to the forum.

 

2nd, shell preserved in this way is often very soft. Sometimes a stiff bristled grout brush will remove it. You can soften it with a bit of denatured alcohol. Nothing is needed to preserve the calcite steinkern. Otherwise, I would follow @Ludwigia's advice.

Thanks for the recommendations everyone, and for the warm welcome from all of you. Glad I asked before trying acetic acid. What are your thoughts on a light PVA application for aesthetic? Worth the effort, or is it more scientifically valuable to keep it natural?

[RJB]

  I would leave it as is, but you can always brush on a quick coat of house hold floor wax and let dry. 

 

RB

[Ptychodus04]

13 hours ago, tjlyons123 said:

Thanks for the recommendations everyone, and for the warm welcome from all of you. Glad I asked before trying acetic acid. What are your thoughts on a light PVA application for aesthetic? Worth the effort, or is it more scientifically valuable to keep it natural?

I would leave it as is. I don't think anything on it would make it look any better. If you want to go for an eye catching display piece, you can always polish the calcite.