Ordovician Prep Questions

[AHoffman]

Hi all,

 

It's been a few years since I've posted here, but I'm hoping to bring some order to my fossil collection and prep some specimens for display. I've tried to glean info from other threads in this sub-forum, but am still trying to figure out how best to approach preserving/restoring Ordovician fossils. As a for instance, how would others approach this rock? It's a piece from southeastern Indiana and contains what I've tentatively identified as Tentaculites sterlingensis and some Flexicalymene pieces parts. Is there any way to make the Tentaculites pop out a little more and clean it up without breaking up the actual fossils? The rock is about the size of my hand. I like how others have given that glossy dark finish to Flexicalymene trilobites; can that be done here?

Thanks for any tips you have and I apologize if this is not the right place to post this particular question.
-Andrew

 

 

[Fossildude19]

Air abrasion would be your best bet here.

That requires an air compressor and an air eraser .  (Think mini-sandblaster.) 

Depending on the hardness of the matrix surrounding the fossils, you can use different media to remove the matrix. 

Sodium Bicarbonate = for soft matrix. 

Calcium carbonate = soft matrix.

Aluminum Tri-hydrate - medium matrix hardness.

Dolomite = medium matrix hardness

 

Some people use Aluminum Oxide for really hard matrix. I have personally found that this is much too hard for most of the fossils I work on.

 

Basically, you are blasting grit at the fossil, and you want something that is harder than the matrix, but softer than the material composing the fossil.

This is what gives many fossils that "polished" look. 

Search the Forum for more info on air abrasion.  

Good Luck.

Regards,

 

[Peat Burns]

What Fossildude19 said.  I'll only add that air abrasion can be a very slow process if you are trying to blast through a lot of matrix.  For your Tentaculites (which are really nice, btw), you may want to start out right away with the air abrasion, because there is only a little bit of matrix between the ridges.  However on some of the trilobite bits and other larger fossils which have deeper contours filled with matrix, I try to remove as much of the matrix as I can by other means before moving to air abrasion (as a final step).  There are many options for matrix removal (including pneumatic scribes, dremel tools, engravers, dental tools, etc.).  But, if I can get away with it (i.e. if the matrix is soft enough), I like to use a pin vice, especially when I am working close to or on the fossil itself.  Here is an example of a pin vice.  I use hypodermic needles in the vices because they are very narrow, sharp, and also flat at the tip (for scraping).

 

Let us know about your progress!

[AHoffman]

Thanks for all of the helpful suggestions!

It seems like air abrasion is the way to go, but it also seems like getting into air abrasion is not a quick or cheap thing. FossilDude - Thanks for the link, is ~$70 pretty standard for the air eraser and I assume that will need to attach it to an air compressor? What kind of price range am I looking at for the whole outfit if I want to do it right? I'm not sure I am in a position to drop $200+ outright on something like that, but I could probably talk myself into putting away some money each month for awhile to buy it at a later date. I also assume it's enough of an art that I don't want to take my best rocks and start shooting air onto them before testing it out on other pieces I don't care as much about?

 

Also, to clarify what you said regarding medium to remove the matrix. Are those settings for the air eraser or are you actually using those substances on the matrix somehow to remove it?

Thanks again,
-Andrew 

[Fossildude19]

On 5/14/2017 at 9:49 AM, AHoffman said:

Thanks for all of the helpful suggestions!

It seems like air abrasion is the way to go, but it also seems like getting into air abrasion is not a quick or cheap thing. FossilDude - Thanks for the link, is ~$70 pretty standard for the air eraser and I assume that will need to attach it to an air compressor? What kind of price range am I looking at for the whole outfit if I want to do it right? I'm not sure I am in a position to drop $200+ outright on something like that, but I could probably talk myself into putting away some money each month for awhile to buy it at a later date. I also assume it's enough of an art that I don't want to take my best rocks and start shooting air onto them before testing it out on other pieces I don't care as much about?

 

Also, to clarify what you said regarding medium to remove the matrix. Are those settings for the air eraser or are you actually using those substances on the matrix somehow to remove it?

Thanks again,
-Andrew 

 

 

Andrew, 

 

Sorry, I missed this some how.  

 

It isn't really cheap to get into, as a compressor is needed, and they cost a bit,  but there are ways to make the process less expensive.  

See the following 2 links. 

 

LINK 1

 

LINK 2

'

Media used means the actual abrasive material you will be shooting out of the air eraser. 

 

You definitely want to practice on pieces that aren't that important to you, to get a feel for how the whole process works - what pressure is correct, what media is correct, etc. 

I always bring extra material home, so that I can try different tools and techniques, media, etc. on the rocks from each locality.

 

Good luck, Andrew. 

Regards, 

 

[Ptychodus04]

You can start very low tech. Dish soap and a stiff brush. Scrub it in with the brush and then brush the "snarge" out of it under running water. This will remove some of the softer matrix. Then, while the matrix is wet, go after it with a sewing needle in the pin vise mentioned above. Work on small areas and rinse the block regularly. 

 

I used to employ this method on Ordovician stuff from Minnesota before I got all the fancy tools.

 

 

[AHoffman]

Thanks for the help everyone!

 

Given my finances, I will have to stay low tech for awhile. I went with the soap, brush, and pin vise suggestion, but used a dental pick as a pin vise substitute until I can find a store that carries pin vises. It's not a major transformation, but I do think it helped bring out the Tentaculites nicely! Below, I've posted before and after shots from a close view and a whole rock view. The yellow tone of the after shots is from the lighting.

 

-Andrew

 

 

[Ptychodus04]

Very nice. It made a big difference.

 

I prepped low tech with hand tools only for about 10 years. That's when I bought my Aro scribe and I could never go back!

 

I've burned through several styli and bushings but the old scribe has stood up to some serious use. The amount you can prep in the same time frame is significant.

[AHoffman]

Thanks Kris,

The wire brush really makes a difference! Does using a (steel/copper) wire brush risk damaging the fossils?

-Andrew

[Ptychodus04]

1 hour ago, AHoffman said:

Thanks Kris,

The wire brush really makes a difference! Does using a (steel/copper) wire brush risk damaging the fossils?

-Andrew

 

Steel can scratch the fossils if you're not careful. I have used steel brushes with good results but you always have to employ a light hand and check after every couple scrubs to make sure you're not damaging the fossils. Brass brushes seem to work well also with less chance of damage that the steel ones.

[JohnBrewer]

On 14/05/2017 at 3:16 AM, Peat Burns said:

What Fossildude19 said.  I'll only add that air abrasion can be a very slow process if you are trying to blast through a lot of matrix.  For your Tentaculites (which are really nice, btw), you may want to start out right away with the air abrasion, because there is only a little bit of matrix between the ridges.  However on some of the trilobite bits and other larger fossils which have deeper contours filled with matrix, I try to remove as much of the matrix as I can by other means before moving to air abrasion (as a final step).  There are many options for matrix removal (including pneumatic scribes, dremel tools, engravers, dental tools, etc.).  But, if I can get away with it (i.e. if the matrix is soft enough), I like to use a pin vice, especially when I am working close to or on the fossil itself.  Here is an example of a pin vice.  I use hypodermic needles in the vices because they are very narrow, sharp, and also flat at the tip (for scraping).

 

Let us know about your progress!

Love the idea of hypodermic needles, not thought of that myself. 

[JohnBrewer]

On 04/06/2017 at 7:57 PM, AHoffman said:

Thanks for the help everyone!

 

Given my finances, I will have to stay low tech for awhile. I went with the soap, brush, and pin vise suggestion, but used a dental pick as a pin vise substitute until I can find a store that carries pin vises. It's not a major transformation, but I do think it helped bring out the Tentaculites nicely! Below, I've posted before and after shots from a close view and a whole rock view. The yellow tone of the after shots is from the lighting.

 

-Andrew

 

 

Nice work Andrew. Pin vices are two a penny on a well known auction site. I got two double ended ones (different collet sizes) for £10.