Large Phylloceras shell prep/polish

[Crann]

How do you guys/gals polish down and what do you use to avoid damage to the fossil ? Thanks.

[Ptychodus04]

This piece doesn't strike me a good polishing material. To get a decent polish, you need a very even surface.

 

Also, in order to polish a fossil, you must damage it (even if it is slight). I start by wet sanding the specimen with 300 grit, moving up to 400, 500, and 600. Then you move to the polish. I use jeweler's rouge on a polishing wheel on my bench grinder. This process works very well. I have only polished baculites and belemnites though.

[caldigger]

Ya, unfortunately polishing kind of ruins the aesthetics of a fossil to me. Even though it might highlight details in patterns and what not. I prefer fossils in their natural state.

Otherwise, they are just pieces of art.

[Crann]

28 minutes ago, caldigger said:

Ya, unfortunately polishing kind of ruins the aesthetics of a fossil to me. Even though it might highlight details in patterns and what not. I prefer fossils in their natural state.

Otherwise, they are just pieces of art.

I agree but this is a large old chunk, nice big ribs underneath the matrix that have nice colours, thought could bring it out a bit, thanks.

[Ludwigia]

Before you polish, you have to sand and that removes a lot of substance. It would certainly eradicate those fine ribs. Is the matrix mineralized? If not, it's not worth the effort.

[Crann]

35 minutes ago, Ludwigia said:

Before you polish, you have to sand and that removes a lot of substance. It would certainly eradicate those fine ribs. Is the matrix mineralized? If not, it's not worth the effort.

It is just shale, I may return it back to the sea tbh, will have a good look soon see what to do, thanks.

[Taogan]

That chunk doesn't look like a good candidate for a polished piece, it is probably too soft. I would just leave it outside to weather for a month or two to see if anything develops. 

[Ptychodus04]

6 hours ago, Crann said:

It is just shale, I may return it back to the sea tbh, will have a good look soon see what to do, thanks.

 

Definitely can’t polish shale. It’s way too soft. 

[Crann]

6 hours ago, Ptychodus04 said:

 

Definitely can’t polish shale. It’s way too soft. 

No I mean there's a shale coating/matrix over the top that I would take off before polishing, thanks.

[JohnBrewer]

Hey Alan, why not remove the shale and post another image? Have you got anything similar you could do a practice on? Can you do a hardness (Mohs)test?