Brachiopod KOH prep

[Peat Burns 1,249]

Here's a nice, large brachiopod I found at Paulding, OH, yesterday.  The Silica Shale is rich in organics and lends itself well to dissolution with KOH, a strong base.  Here is the "before" pic after cleaning the fossil with a brass brush.  The remaining matrix is rock, not "dirt" and would take quite a bit of time to remove with a pin vice and air abrasion.

 

 

 

[Peat Burns 1,249]

Here's the same fossil after being sprinkled with KOH flakes and left to set for 8 hours followed by rinsing and soaking in water to remove KOH residue. (Scale in mm)

 

WARNING: KOH is very caustic.  Use only in well-ventilated area (I use a laboratory fume hood).  Keep away from children and pets.  Avoid contact with skin, etc.

[doushantuo 2,765]

Nice work,Peat,lovely sclerobionts on that one.

I like it!

 

[Peat Burns 1,249]

3 minutes ago, doushantuo said:

Nice work,Peat,lovely sclerobionts on that one.

I like it!

 

Thanks, dou. You'd love this site.  RICH in epibiota.  This particular one is the coral Aulopora microbuccinata

[doushantuo 2,765]

BTW: amazing "before" and "after" pix.

I rinse my face with KOH each morning,saves shaving time*

EDIT:

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[Peat Burns 1,249]

Just now, doushantuo said:

BTW: amazing "before" and "after" pix.

I rinse my face with KOH each morning,saves shaving time

Hahahaha!

[Tidgy's Dad 4,373]

Beautiful brachiopod, and the coral is great, too.

Very informative as well. 

Lovely prep job. 

[RJB 911]

Hey @Peat Burns, im not much into the brach's, I think the west coast is not known for brachs?, but you mention you used a 'brass' brush.  The one and only time I tried a brass brush for cleaning left a very brassy and gold colored look on the fossil.  Your fossil does not appear to look that way after the brush treatment?  I dont undstand this?

 

RN

[digit 1,529]

8 hours ago, Peat Burns said:

The Silica Shale is rich in organics and lends itself well to dissolution with KOH, a strong base.

Very nice! I have some similar brachiopods from Indiana (St. Leon road cut). I experimented with acid solutions of various strengths both to try to clean the crud off of some small separate individuals as well as trying to "unlock" some items from hash plates. I experimented with small broken pieces that I was willing to lose during the experiment which was good because with sufficiently strong acid like Muriatic (HCl) I was able to dissolve everything into a gray paste.

 

Never thought of going the other direction on the pH scale. Though I've recently given away the last of my hash plates, I still have a few brachiopods with which I'd enjoy trying to repeat your success. I'm wondering where you procured your KOH? I know I can get sodium hydroxide NaOH (lye) off the shelf as "crystal drain opener" but I only seem to be able to find KOH (potassium hydroxide) online for the purpose of creating homemade soaps or the production of biodiesel. While searching the internet I came across a concept that initially seemed oxymoronical but, in fact, makes sense upon further thought--food grade NaOH (lye).

 

 

It took me a beat to remember that lye is used in converting corn kernels to Hominy and anybody making their own German pretzels would soak them in lye before baking to get the distinctive crust. Not quite as ridiculous as food grade Arsenic but I did find the phrase "food grade lye" a bit humorous (alright, I have an odd sense of humor).

 

Will let you know if I am able to find a strong alkaline compound to repeat your process. Thanks for the idea. Oh, and anybody else who tries this--please do be careful this stuff can be dangerous!

 

 

Cheers.

 

-Ken

[caldigger 2,726]

This may be a stupid question, but these "flakes" you talk about don't require wetting?  You just put dry substance on the fossil and it disolves the crud?

[digit 1,529]

From the little I know about KOH, it is very hygroscopic. Sprinkling some dry flakes on the brachiopod would seem to be enough, they should pull moisture out of the air and "melt".

 

 

Cheers.

 

-Ken

[Peat Burns 1,249]

3 hours ago, caldigger said:

This may be a stupid question, but these "flakes" you talk about don't require wetting?  You just put dry substance on the fossil and it disolves the crud?

 

3 hours ago, digit said:

From the little I know about KOH, it is very hygroscopic. Sprinkling some dry flakes on the brachiopod would seem to be enough, they should pull moisture out of the air and "melt".

 

 

Cheers.

 

-Ken

Yes, you can just sprinkle the flakes on dry, and they will draw moisture from the air and "do their thing". The reason i moisten the fossil first is simply to get the flakes to stick so they don't tumble off.

[Peat Burns 1,249]

6 hours ago, RJB said:

Hey @Peat Burns, im not much into the brach's, I think the west coast is not known for brachs?, but you mention you used a 'brass' brush.  The one and only time I tried a brass brush for cleaning left a very brassy and gold colored look on the fossil.  Your fossil does not appear to look that way after the brush treatment?  I dont undstand this?

 

RN

You are correct. My brush will do that if I scrub something really hard. But if I'm not too aggressive with it, it won't leave any color. Maybe mine is not real brass or a different alloy?

[minnbuckeye 617]

@Peat Burns, what do you think about using KOH on the Paulding fenestrated bryozoa and corals to clean them up. I have tried KOH on local matrix and acid seems to work better.

[Peat Burns 1,249]

1 minute ago, minnbuckeye said:

@Peat Burns, what do you think about using KOH on the Paulding fenestrated bryozoa and corals to clean them up. I have tried KOH on local matrix and acid seems to work better.

I'm afraid it would destroy the bryozoan.  In many cases those fenestrate bryozoans are just molds of the original and don't have any calcified exoskeleton remaining.  If there's no calcified exoskeleton (or insufficiently calcified), the KOH would turn it to mud.  You could try it on a tiny corner with a flake or two.

[caldigger 2,726]

4 hours ago, digit said:

From the little I know about KOH, it is very hygroscopic. Sprinkling some dry flakes on the brachiopod would seem to be enough, they should pull moisture out of the air and "melt".

 

 

Cheers.

 

-Ken

Very interesting to know.  I dont know how much moisture it could draw out of the air here, it's pretty dry.

Humidity is a foreign word to us. 

[digit 1,529]

I'll trade you--yardwork in South Florida becomes near impossible at this time of the year. Temps in the 90's and heavy humidity make me liquefy into a puddle of sweat. I enjoyed my recent travels with the temps in the 40's.

 

I suspect wetting the fossil as mentioned before sprinkling the flakes would get things started.

 

 

Cheers.

 

-Ken

[Peat Burns 1,249]

5 hours ago, digit said:

Very nice! I have some similar brachiopods from Indiana (St. Leon road cut).

Thanks, Ken.  I've never tried it on the St. Leon material yet.  I may throw some on tonight and see if it works.  Not sure how many organics are present in that stuff.  I've had zero luck with acid.  It discolors and damages all the material I've tried.

 

5 hours ago, digit said:

I'm wondering where you procured your KOH? I know I can get sodium hydroxide NaOH (lye) off the shelf as "crystal drain opener" but I only seem to be able to find KOH (potassium hydroxide) online for the purpose of creating homemade soaps or the production of biodiesel.

The lab grade KOH (unnecessary for this purpose) is extremely expensive.  I can buy huge quantities very cheaply online (also sold for soapmaking, etc.).  The NaOH will probably work, too.

 

5 hours ago, digit said:

Oh, and anybody else who tries this--please do be careful this stuff can be dangerous!

Can't stress this enough.  This is not table salt, folks. It does produce odorless fumes that can and will damage your lungs before you know it.  It will also burn skin.  

[digit 1,529]

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

[RJB 911]

22 hours ago, Peat Burns said:

You are correct. My brush will do that if I scrub something really hard. But if I'm not too aggressive with it, it won't leave any color. Maybe mine is not real brass or a different alloy?

I went out and bought some little stainless steal brushes. 

 

RB

[ynot 4,355]

1 hour ago, RJB said:

I went out and bought some little stainless steal brushes. 

 

RB

Stainless steel is harder than brass/bronze and will damage the surfaces of softer fossils.

[Manticocerasman 239]

I love the result you got there, I might give it a try on some of my specimens

 

[digit 1,529]

Before I went out to buy some KOH flakes I tried some "liquid plumber" type solutions that are a combination of KOH and NaOH (of unknown strength). No particular affect on the matrix on brachiopods from the St. Leon roadcut in Indiana. Just thought I'd pass that along if anybody else was interested in trying this method on items from that locality.

 

 

Cheers.

 

-Ken

[RJB 911]

22 hours ago, ynot said:

Stainless steel is harder than brass/bronze and will damage the surfaces of softer fossils.

I never thought of that?  Its amazing how a guy like me can know soooooooooo much, and at the same time, not know a whole lot. 

 

RB

[DLB 73]

Wait wait wait let me get this right it draws fat out?