Brachiopod KOH prep

[DLB]

On 7/10/2018 at 11:24 AM, digit said:

Indeed!

 

I remember playing with these strong alkalines eons ago in a college organic chemistry class. The first indication that you've gotten some on your fingers is the slippery feeling that is the result of the chemical pulling the fats out of our skin tissue and turning them to soap.

 

Don't mess around with this stuff without adequate protection--it's particularly difficult to type messages into TFF with soapy fingers. 

 

 

Cheers.

 

-Ken

So you're telling me if I rub this on my belly I'll lose weight? Lol

[digit]

In the most painful way imaginable (even worse than exercise).

 

 

Cheers.

 

-Ken

[Mediospirifer]

Nice!!

 

I'll have to try that on a few Cincinnatian (St. Leon & other sites) brachs. I have a couple of sandwich bags of similar ones, collected in the search for pathological specimens. I've been trying to clean some with toothbrush and dental pick, and have been having a hard time recognizing where the matrix stops and the fossil begins! I actually turned to the Preparation subforum with the thought of posting a thread asking for helpful suggestions...

 

Speaking of which, did you notice that your specimen is pathological? It has two visible clefts (healed scars from being notched), one on either side. Look for distortions in the ribs. Nice piece!

 

[Peat Burns]

On 7/18/2018 at 2:57 PM, Mediospirifer said:

Nice!!

 

I'll have to try that on a few Cincinnatian (St. Leon & other sites) brachs. I have a couple of sandwich bags of similar ones, collected in the search for pathological specimens. I've been trying to clean some with toothbrush and dental pick, and have been having a hard time recognizing where the matrix stops and the fossil begins! I actually turned to the Preparation subforum with the thought of posting a thread asking for helpful suggestions...

 

Speaking of which, did you notice that your specimen is pathological? It has two visible clefts (healed scars from being notched), one on either side. Look for distortions in the ribs. Nice piece!

 

Thanks. I haven't tried it on St. Leon stuff yet, but I think digit did with little luck.  It may be that there is not enough organic material in that matrix.

 

I hadn't noticed the pathology.  Thanks for pointing it out. 

 

You are talking about this, right?

 

I have a horn coral from Paulding that I did with the KOH that I'll post soon.  Turned out great. 

[Mediospirifer]

That's the larger mark. There's another distortion in the green loop:

 

 

I'll be interested to see your horn coral. I'll be working on a few test brachs over the next couple of days. I work in a chemistry lab; one of my chemist co-workers said he'd be happy to help. So, I'll bring my pieces in tomorrow and set them in a dish, he'll sprinkle them with KOH when he comes in on Tuesday morning, then we'll wash them off late Tuesday afternoon before I go home. I plan to take some "Before" pix tonight, I'll see what they look like on Tuesday for "After"!

 

[digit]

Great! Love to hear more about this interesting method of clearing matrix off these specimens. Let us know how it turns out.

 

Cheers.

 

-Ken

[Peat Burns]

2 hours ago, Mediospirifer said:

I'll be interested to see your horn coral.

Here is the before and after of the Paulding horn coral. Although one might worry that the KOH removed the epitheca (as would be the case if acid was used), careful examination of the coral prior to treatment indicates the epitheca had worn away prior to fossilization. The KOH only dissolves the organic material from the matrix, turning it into a slurry, so the fossil itself, being calcitic, is not harmed.

 

The calyx in this specimen was filled with at least a half inch of matrix. The KOH had turned it to mud within a day.

 

Scale is in mm.

[Mediospirifer]

Very nice! Makes me want to try the treatment on some of my NY Devonian fossils. I have a lot of horns that look like your first one...

 

[digit]

Stunning!

 

My attempts at repeating this with specimens from the St. Leon roadcut and a more dilute solution of KOH/NaOH didn't produce any results but I'm going to have to get some KOH flakes and try this again in earnest with the more concentrated application of a strong alkaline.

 

 

Cheers.

 

-Ken

 

[Mediospirifer]

Well, so far, not much. I brought 4 small pieces of brachiopod hash into the lab, we applied a few bits of dry KOH to wet fossils, and let them sit for the day. One of the hash pieces started to fragment; beyond that, its hard to say whether there was any change. I left the pieces in the hands of my co-worker for further tests. He's planning to mix up a solution and soak them for a while. I'll see on Thursday what they look like.

 

When I go back in on Thursday, I plan to bring in some miscellaneous Devonian pieces from the Windom shale--horn corals, bryozoan pieces, maybe some brachs. If this works, I have a lot of pieces I'd love to prep!

 

[Peat Burns]

3 minutes ago, Mediospirifer said:

Well, so far, not much. I brought 4 small pieces of brachiopod hash into the lab, we applied a few bits of dry KOH to wet fossils, and let them sit for the day. One of the hash pieces started to fragment; beyond that, its hard to say whether there was any change. I left the pieces in the hands of my co-worker for further tests. He's planning to mix up a solution and soak them for a while. I'll see on Thursday what they look like.

 

When I go back in on Thursday, I plan to bring in some miscellaneous Devonian pieces from the Windom shale--horn corals, bryozoan pieces, maybe some brachs. If this works, I have a lot of pieces I'd love to prep!

 

From which formation was your hash test piece?

[Mediospirifer]

Either Waynesville or Liberty; both are exposed at the roadcut. The chief component of the hash is Glyptorthis insculpta, which (if I recall correctly) is mostly known from the Liberty. They're Upper Ordovician, Cincinnati group.

 

This is the site and species that has provided me with the most pathological specimens, near Brookville, IN.

 

[Peat Burns]

Just now, Mediospirifer said:

Either Waynesville or Liberty; both are exposed at the roadcut. The chief component of the hash is Glyptorthis insculpta, which (if I recall correctly) is mostly known from the Liberty. They're Upper Ordovician, Cincinnati group.

 

This is the site and species that has provided me with the most pathological specimens, near Brookville, IN.

 

Oh, ok. Yeah, I tried some on a hash plate from there with little to no effect also.  Probably not very much organic matter there.  It should work well on any dark shales like Hamilton Group, etc.

[Mediospirifer]

27 minutes ago, Peat Burns said:

Oh, ok. Yeah, I tried some on a hash plate from there with little to no effect also.  Probably not very much organic matter there.  It should work well on any dark shales like Hamilton Group, etc.

 

I hope so! I have a collection of bryozoan pieces (Atactotoechus fruiticosus) from a single specimen that I hope to be able to clean up before gluing it back together. It'll be a nice big tree with lots of epibionts when I'm done.

 

[ricardo]

Hello, thats a good way to clean those kind of fossils with marls over it. A friend use it in this way:

 

Use potash (KOH) to remove the marl components, very carefully because this product is higly corrosive and hurts if not caution. After cleaning, with a pair of sessions  we have to neutralize the KOH with vinegar, a soft acid and soft brush. And finally several days into a can of water, changing water each day. This way the KOH dissolves in the water and dissapear (is a product quite persistent).

 

Regards,

 

Ricardo

[Mediospirifer]

After a week-long hiatus (things are busy at work, so my colleague was too busy to do anything with my samples), we put three Devonian pieces (2 corals and a bryozoan 'stick') in a 2.5 M (molar) solution over the weekend. At a casual glance, there doesn't appear to be much change, but I think the bryozoan shows more detailed structure on the surface. I need to check the photos I took last week to compare!

 

I'm currently soaking the pieces in water. I'll take them home tonight and see if a toothbrush takes any further residue off.

 

Peat Burns, was there a significant amount of muddy residue left when you treated the coral above? My pieces lost a few chips, but not much mud (unless my colleague washed the mud down the drain without telling me; he just brought the washed pieces to my desk). My large horn coral also still has most of the matrix embedded in the calyx.

 

I'll post further results (and pictures) as I have them.

 

[Peat Burns]

8 minutes ago, Mediospirifer said:

After a week-long hiatus (things are busy at work, so my colleague was too busy to do anything with my samples), we put three Devonian pieces (2 corals and a bryozoan 'stick') in a 2.5 M (molar) solution over the weekend. At a casual glance, there doesn't appear to be much change, but I think the bryozoan shows more detailed structure on the surface. I need to check the photos I took last week to compare!

 

I'm currently soaking the pieces in water. I'll take them home tonight and see if a toothbrush takes any further residue off.

 

Peat Burns, was there a significant amount of muddy residue left when you treated the coral above? My pieces lost a few chips, but not much mud (unless my colleague washed the mud down the drain without telling me; he just brought the washed pieces to my desk). My large horn coral also still has most of the matrix embedded in the calyx.

 

I'll post further results (and pictures) as I have them.

 

I find that putting them in liquid solution, even at high concentrations, doesn't work nearly as well as applying flakes directly to the fossil.  

 

Yes, after application of flakes there is quite a bit of mud that rinses off easily.  A tooth brush removes any more sticky residue.  I repeat process if more matrix needs to come off (there is a limit to the depth of matrix one application will remove).

 

From what formation were your Devonian tests?

 

I've only tried Silica Shale so far.

[Mediospirifer]

43 minutes ago, Peat Burns said:

I find that putting them in liquid solution, even at high concentrations, doesn't work nearly as well as applying flakes directly to the fossil.  

 

Yes, after application of flakes there is quite a bit of mud that rinses off easily.  A tooth brush removes any more sticky residue.  I repeat process if more matrix needs to come off (there is a limit to the depth of matrix one application will remove).

 

From what formation were your Devonian tests?

 

I've only tried Silica Shale so far.

 

Windom shale, Hamilton group, Moscow formation, Middle Devonian.

 

Should I dampen the corals and roll them in flakes next time?

 

[Peat Burns]

4 minutes ago, Mediospirifer said:

 

Windom shale, Hamilton group, Moscow formation, Middle Devonian.

 

Should I dampen the corals and roll them in flakes next time?

 

Yes, I wet the fossils first so that the flakes stick where I want them.  Let us know how it works.  I haven't tried Penn Dixie material yet.  I don't try to do the whole fossil at once.  I pile flakes in one area ,clean, and do another side / area.

[Mediospirifer]

Good to know. I'll talk to my colleague about this, and we'll see how things go.

 

I'll post the results when I have some.

 

[Peat Burns]

2 hours ago, Mediospirifer said:

Good to know. I'll talk to my colleague about this, and we'll see how things go.

 

I'll post the results when I have some.

 

By the way.  Do not attempt on trilobites. The KOH will seep under the exoskeleton and undermine the supporting matrix and turn the fossil into a 3D puzzle

[Mediospirifer]

I thought that was likely to be the case, and therefore wasn't planning to treat any bugs.

 

Thanks for the heads-up!

 

[DLB]

Peat Burns will KOH desalve mineralized bones? Like from a kechisorus?

[Peat Burns]

11 minutes ago, DLB said:

Peat Burns will KOH desalve mineralized bones? Like from a kechisorus?

Good question. Modern, non-mineral-replaced bone is calcium phosphate plus organic material like collagen.  KOH would definitely dissolve collagen, but shouldn't dissolve the strictly mineral components.  So on old fossils like keichosaurus, it should not dissolve the bone. However, if the shale is rich in organics, the KOH could undermine the bone turning the supporting shale to mud and dislodging the bone. Not good.  I'd try some microscale tests before I got too aggressive with it.  Be careful!

[DLB]

 

1 hour ago, Peat Burns said:

Good question. Modern, non-mineral-replaced bone is calcium phosphate plus organic material like collagen.  KOH would definitely dissolve collagen, but shouldn't dissolve the strictly mineral components.  So on old fossils like keichosaurus, it should not dissolve the bone. However, if the shale is rich in organics, the KOH could undermine the bone turning the supporting shale to mud and dislodging the bone. Not good.  I'd try some microscale tests before I got too aggressive with it.  Be careful!

so i might get the first 3D keichosaurus lol. might be kinda cool in a way