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Sacha

Any secrets to removing red clay?

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Sacha

There are lots of locations in the country where the fossils we collect are found associated with red soil or persistent red clay. This isn't a rust stain, but the very fine grains embedding themselves on the porous surface of the fossil, in the following picture the subject is specifically echinoids. Is there a secret way of removing this coloration? The Wythella eldridgei are particularly fragile, so I was concerned about ultrasonic cleaning or heavy scrubbing. Any tips?

 

DSCF1641.thumb.jpg.d6d722d5a125480f6e4858cc7b02bcf6.jpg

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caldigger

Well if we told you, it wouldn't be a secret anymore!

 

I wonder if you would get any reaction on those echinoids from a soaking in Hydrogen Peroxide.  Marcos Sr. told me a good tip to soak the "micros" in it to dissolve and dislodge the stubborn matrix particles.  

I have tried it on several different fossils I have and they clean up with pretty good success.

Maybe you could try it on a lesser one to experiment.

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Sacha
27 minutes ago, caldigger said:

Well if we told you, it wouldn't be a secret anymore!

 

I wonder if you would get any reaction on those echinoids from a soaking in Hydrogen Peroxide.  Marcos Sr. told me a good tip to soak the "micros" in it to dissolve and dislodge the stubborn matrix particles.  

I have tried it on several different fossils I have and they clean up with pretty good success.

Maybe you could try it on a lesser one to experiment.

 

I tried 3% for a short time and got no reaction. I expected to see bubbles. The sand dollar was still wet. Maybe I need to get the hightest strength and soak overnight. 

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caldigger

Ok...or you can just go get some "Iron Out" at the hardware store.

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Sacha

Very informative but not applicable. Not iron staining , but red clay particles imbedded in the porous structure of the fossils.

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Mark Kmiecik

Soak it if it can handle it -- dental picks with 10x magnification. Pick it off a grain at a time. Hours of tedious work, therefore, only prep the ones worth the time. I would definitely prep the big one. How many more is up to you. Do you think you'll find more that are in better condition? Soon? For sure?

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Sacha
1 hour ago, Mark Kmiecik said:

 Do you think you'll find more that are in better condition? Soon? For sure?

 

Only time will tell. Will certainly give it a shot.

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Mark Kmiecik
Just now, Sacha said:

 

Only time will tell. Will certainly give it a shot.

What I meant by those questions is that if the chances are quite good that you'll find a better specimen soon don't bother putting in the time to prep the lesser one. That time, which can be hours, is better spent looking for more fossils. Of course you need to hunt a location a few times before you have a good idea of what it will probably produce, but sometimes even only one trip can hint at the possibilities.

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Randyw

I don’t know if I agree with that. These alllook like really nice specimens and worth a little tlc.if they were mine I’d try a soft bristled tooth brush maybe even one of the ones for babies and some gently moving water.maybe a trickling faucet over a bowl just in case. But take my advice with a grain of salt. I don’t believe there is such a thing as an unworthy fossil. Also if he does it at night even for a few minutes he’s not losing any fossil hunting time LOL! Also I love prepping (I’m weird I know) so I don’t consider time spent prepping anything as wasted

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oilshale
7 hours ago, Sacha said:

Very informative but not applicable. Not iron staining , but red clay particles imbedded in the porous structure of the fossils.

 

From https://sciencing.com/red-clay-22940.html :

Clay Composition:
Clay particles contain silica (SiO2) and a mixture of other minerals, such as quartz, carbonate, aluminum oxides and iron oxides. The ratio of SiO2 to other clay minerals within clay determines clay type. Continued weathering of clay causes leaching of minerals, such as sodium, potassium, calcium and carbonate, but iron and aluminum oxides are more stable and less likely to leach out. Highly weathered clay deposits contain mostly aluminum or iron oxides, the minerals in red clay.

You can't remove the clay but possibly the red color.

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Mediospirifer

I'd try the peroxide again. Dry the fossil thoroughly before soaking--wet clay is pretty impermeable to aqueous solutions, but dry clay should soak it right up. At least in theory; I haven't tried much with peroxides.

 

I've also seen something called Rewoquat (marketed as Varisoft in the US) recommended for breaking down clay minerals. I haven't tried that yet, but it might help.

 

Good luck!

 

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Mark Kmiecik
On 7/10/2019 at 4:35 PM, Sacha said:

Very informative but not applicable. Not iron staining , but red clay particles imbedded in the porous structure of the fossils.

Iron oxide is what makes red clay red. It might work.

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