prep on crinoids

[Barby]

I have a shale/slate slab with some crinoid blooms and misc. other marine organisms----I have an assortment of Dremel bits and 3 sizes of air scribe stilettos.

I'm wanting information as how to begin--I've read that muriatic acid can be useful, with care and controlled exposure.

My concern is the fragility of the smaller/thinner objects next to the larger ,more sturdy ones.

What approach would be the best , least damaging way to go?

Any help will be appreciated!

[FossilDAWG]

We would have to see some photos in order to be able to offer much in the way of useful advice.

 

I would strongly suggest that you do not use muriatic acid.  This approach only works on fossils that have been replaced by silica and are embedded in a carbonate (limestone) matrix.  This acid will not remove shale or slate.  On the other hand, the hard parts of echinoderms (including crinoids) are composed of calcite, which is easily dissolved by the acid.  The vast majority of the time, treating crinoids in shale with muriatic acid will only dissolve the fossil, leaving the shale intact, exactly the opposite of what you want.

 

Don

[Malcolmt]

Photos are a must

[Barby]

18 hours ago, Malcolmt said:

Photos are a must

Thank  you.

[Barby]

19 hours ago, FossilDAWG said:

We would have to see some photos in order to be able to offer much in the way of useful advice.

 

I would strongly suggest that you do not use muriatic acid.  This approach only works on fossils that have been replaced by silica and are embedded in a carbonate (limestone) matrix.  This acid will not remove shale or slate.  On the other hand, the hard parts of echinoderms (including crinoids) are composed of calcite, which is easily dissolved by the acid.  The vast majority of the time, treating crinoids in shale with muriatic acid will only dissolve the fossil, leaving the shale intact, exactly the opposite of what you want.

 

Don

This is a HARD shale slab. I had read that muriatic acid is used on some items, but I did not know how, when, and when NOT. Your response is exactly what I wanted to know: DON'T!

Plus, it was interesting to learn just how the acid affects the item.Very informative--thank you, Don.

Barb

[FossilDAWG]

Glad to help!

 

We have several members who have a lot of experience at prepping crinoids.  If you post some photos I'm sure they can offer some practical advice.

 

Don

[Mark Kmiecik]

You can always try some on the back side of the plate or in an inconspicuous spot if you want to know what it will do. Or go out and get another piece that's "less than collectible" and try it on that. Remember that Muriatic is the hardware store name for diluted Hydrochloric acid, one the extremely reactive and dangerous acids around. It would be prudent to try something milder and less expensive like vinegar for the initial tests.

 

Before you try any kind of prep, I advise you to post some photos of the specimen. 

[Barby]

Thank you again--will try that--and-- have taken photos, which I will post.But- the "crinoids" right now are lumps, which I hope are a couple of blooms--then--there's the whole other side....

Barb

 

  

[Jackson g]

The limestone I work off of Burlington crinoids is usually pretty workable. Pictures would be nice. But if it is shale you say your working on, I would recommend using light scribe work and then going to air abbraisives. Your goal is to get most of the hard overburden rock off, so the abrasives will eat away the thin layer left without damaging your fossil. I prefer aluminum oxide (mainly 120 and 240 grit) as my abrasive, but I work typically on hard limestones. Don't use acid, more than likely you will not get the result you want. Try as @Mark Kmiecik suggested and get similar stone and see what works best on it.

Regards, Jackson

[FossilDAWG]

BTW when you say "blooms", you are aware that crinoids are not plants?

 

Don

[Fossildude19]

Pictures posted.

@Barby

[Barby]

Thank you!

I have the air scribe tools, and dremels ,but none of the mild abrasive "sand blasting" tools. You F.F.folks have been very helpful about what NOT to do--which was my major concern.

Barb

[derhuene]

On 11/3/2019 at 6:06 PM, Barby said:

This is a HARD shale slab. I had read that muriatic acid is used on some items, but I did not know how, when, and when NOT. Your response is exactly what I wanted to know: DON'T!

Plus, it was interesting to learn just how the acid affects the item.Very informative--thank you, Don.

Barb

I tried Muriatic acid once and inverted the fossils. Still looked interesting but the actual fossil was gone. 

[Barby]

Thanks to all the advice from the F.F. folks, I dismissed the idea of acids of any kind. Yesterday, I tentatively started on a small section, using a medium air scribe stylus at low speed to detail out the protruding fossils. Then I used a wire wheel bit on my dremel--medium speed--little pressure-- and --BOOM!--all kinds of tiny marine critters showed up.I was afraid that I'd whisk them off--but actually lost very few. So far , there are a couple of nice shiny trilobites.

Also. so far--the "lumps"which I'd hoped might be crinoid calix--are actually just non-organic blobs.

Oh, well--

[Fossildude19]

On 11/6/2019 at 10:35 AM, Barby said:

Thanks to all the advice from the F.F. folks, I dismissed the idea of acids of any kind. Yesterday, I tentatively started on a small section, using a medium air scribe stylus at low speed to detail out the protruding fossils. Then I used a wire wheel bit on my dremel--medium speed--little pressure-- and --BOOM!--all kinds of tiny marine critters showed up.I was afraid that I'd whisk them off--but actually lost very few. So far , there are a couple of nice shiny trilobites.

Also. so far--the "lumps"which I'd hoped might be crinoid calix--are actually just non-organic blobs.

Oh, well--

Pictures, please!  

[Barby]

Tim--I posted 2 pix earlier this week. I have trouble navigating in F.F.-never sure where to go--OR where I am!

Barb

[Mark Kmiecik]

On 11/8/2019 at 9:10 AM, Barby said:

Tim--I posted 2 pix earlier this week. I have trouble navigating in F.F.-never sure where to go--OR where I am!

Barb

I think he meant the "after" photos. I would also like to see how it turned out.

[Barby]

Oh--probably so.

It's coming along well---3 trilobites have shown up so far--one with antennae intact---not much more so far, but there's lots more visible on the reverse side. The slab is 2-3 inches thick. I discontinued using my air scribe ---switched to an abrasive Dremel bit and a wire brush, and--so far, I have been able to expose stuff without damaging them.

[Ludwigia]

On 6.11.2019 at 4:35 PM, Barby said:

Thanks to all the advice from the F.F. folks, I dismissed the idea of acids of any kind. Yesterday, I tentatively started on a small section, using a medium air scribe stylus at low speed to detail out the protruding fossils. Then I used a wire wheel bit on my dremel--medium speed--little pressure-- and --BOOM!--all kinds of tiny marine critters showed up.I was afraid that I'd whisk them off--but actually lost very few. So far , there are a couple of nice shiny trilobites.

Also. so far--the "lumps"which I'd hoped might be crinoid calix--are actually just non-organic blobs.

Oh, well--

I was kinda wondering about that on hand of your photos. As you say, oh well. You can't win them all, but at least you have some other interesting things on that block. I'd also be interested to see what you have if you could post some more pics.

[Barby]

OK-- I will post when I finish--it will be a while--I live in Florida. USA, and it's still too hot to prep outside until late afternoon.( And TOTALLY too messy to prep indoors!)