Using Peroxide

[Raistlin]

I use peroxide to clean my Smithville stuff because it is silicified. Will it hurt other stuff such as limestone or other fossil material?

[jkfoam]

Robert,

I have used peroxide to remove fossils from clays without any harmful effects to the fossils which are mostly mollusks composed of the origional calcium carbonate material.

Jim

[Raistlin]

Good to hear. The Smithville stuff is often in this God awful thick red clay. This is the best way to clean them from what I have seen.

I was wondering about other material though. Thanks, I think I will test it on some other stuff too.

[Fossildude19]

Robert,

As a general rule, I try to stay away from chemicals, but if you do try it on different materials, make sure you do it in a well ventilated area, and make sure you use b or c grade specimens for practicing.

Regards,

[Raistlin]

Thanks.

I was thinking of trying using it a bit on some Golconda stuff and similar. The Golconda stuff is limestone so I was not sure if it would hurt that or not. The Smithville stuff comes out looking very good after a few minutes in peroxide.

I could be wrong but I was under the impression that peroxide broke down into safe chemicals. Not that I would drink the stuff when I was done, but I thought it was just water after break down. I guess I should clarify that I am just using the cheap grocery store stuff nothing stronger.

[mikecable]

3% drugstore or dollar store hydrogen peroxide is my go to chemical for cleaning fossils or breaking down matrix. Sometimes I kick up the power by adding Oxy Clean, by using a small ultrasonic cleaner, or both.

I'm a sixth grade science teacher, which means I know almost nothing. But I wouldn't hesitate to use any of these methods in my lab with kids.

Peroxide seems to be much more forgiving than vinegar. FWIW.

[Raistlin]

So a small untrasonic cleaner will work? I was wondering about that.

Using the two together could work much better I think. I had not heard of using the Oxy Clean but I guess it could work, after all Billy Mayes said it cleaned great lol.

I think Will check into a small ultrasonic cleaner.

Have you had a fossil come apart due to micro cracks already present?

[mikecable]

I'm sure I've had many fossils come apart because of micro fractures. I never saw them closely enough to know they had the fractures in the first place.

Dealing with micros requires a certain amount of zen. You sneeze and a hundred fossils are lost. You hiccup and ten fossils are lost. You blink and a fossil is lost.

But there are many micro fossils grasshopper. Move on to the next.

[Raistlin]

Would a heated ultrasonic be better than a nonheated? Or do you think it matters?

[mikecable]

Would a heated ultrasonic be better than a nonheated? Or do you think it matters?

Heated might be better, but why not just start with hot water? There seems to be a significant price difference.

[Raistlin]

Thanks, I just ordered a small one to start.

It will hold about 20 oz. I think I will pick up some Oxy clean as well and try the combo like you were talking about. I might be able to get these Smithville fossils even cleaner.

Thanks for the ideas.

[Vordigern]

Ive used peroxide on NJ Marl with some success.

[Raistlin]

Good to hear. It works wonders on the Smithville stuff. The red clay in the Smitthville caused me a lot of mom yelling at me as a kid because it is a real pain once you get it on your clothes.

The Golconda stuff I does not seem to have any clay, at least not that I have seen. I am also wanting to try it on Fern Glen and see how that works. I did not know if it would hurt the limestone though. I was not sure if it would be like vinegar in a way just not as agressive.

[mikecable]

Good to hear. It works wonders on the Smithville stuff. The red clay in the Smitthville caused me a lot of mom yelling at me as a kid because it is a real pain once you get it on your clothes.

The Golconda stuff I does not seem to have any clay, at least not that I have seen. I am also wanting to try it on Fern Glen and see how that works. I did not know if it would hurt the limestone though. I was not sure if it would be like vinegar in a way just not as agressive.

I'm not a chemist, just a 6th grade science teacher. So take this for what it's worth. I believe the calcium carbonate in limestone (being alkaline) will act as a catalyst in the decomposition of the hydrogen peroxide into water and oxygen, speeding up the decomposition, resulting in bubbling and fizzing. The tiny oxygen bubbles are the mechanism for breaking down the matrix and or cleaning the material.

Acetic acid (vinegar) and calcium is a much different reaction. The vinegar breaks down both the calcium and the carbonate. That's why the use of vinegar on limestone matrix with fossils that are not silicified, but calcareous must be done very judiciously.

Edited March 5, 2013 by mikecable

[mikecable]

I just confirmed what I thought. This is from a paper titled "Use of Hydrogen Peroxide in the Disintegration of Shales". I. Weihmann, Canadian Gulf Oil Co.

"The method is based on the unstableness of hydrogen peroxide and its decomposotion to water and oxygen. The alkali compounds in the shale act as catalyst accelerating the liberation of oxygen from hydrogen peroxide. This exothermal reaction supplies sufficient heat to speed up the decompositoon without requiring outside energy. The liberation of oxygen takes place with rapid successions of minute explosions. These break up the shale facilitating further penetration with hydrogen peroxide until all the shale is disintegrated.

Although hydrogen peroxide is a weak acid, it is known from experience that it will not harm calcareous microfossils."

It's basically the exact same reaction with limestone as with shale. The author was using 10-15% hydrogen peroxide, so I don't see how 3% hydrogen peroxide from the drugstore is going to cause any harm.

Edited March 5, 2013 by mikecable

[Raistlin]

The 3% stuff does a great job on the stuff I tried it on. I guess the 10-15% stuff would do the same thing only faster?

For the uses I have planned I think the 3% stuff will work great. I doubt I would need anything stronger.

[mikecable]

The 3% stuff does a great job on the stuff I tried it on. I guess the 10-15% stuff would do the same thing only faster?

For the uses I have planned I think the 3% stuff will work great. I doubt I would need anything stronger.

The only thing you are doing by adding OxyClean, or anything like it, is slightly upping the percentage of hydrogen peroxide, and adding a mild detergent. OxyClean is sodium percarbonate--when it breaks down it becomes hydrogen peroxide and sodium carbonate (washing soda or soda ash). I believe it speed things up a bit, but not necessarily enough to make it worth the additional expense for large quantities of matrix.

But it is cool to kick up the reaction where you have fizzing, bubbles, foam and visible water vapor. You can literally make your matrix smoke. Cool beans.

[Raistlin]

Haha sounds like fun. I will have to do it and show my son.

[BobWill]

I've seen posts about this here before and the only thing I can remember without doing a search is that peroxide is fine for shales and clays but to dissolve limestone effectively you need vinegar or even muric acid diluted 10:1 as long as you're careful enough to stop the reaction before you damage the fossil (sometimes a few seconds).

edit: Good ventilation is critical when using stronger acids.

Edited March 11, 2013 by BobWill

[Boneman007]

Ultrasonic cleaners are the best way to destroy fine fossils I've experienced so far.

That vibration will cause a fossil to just fall apart if it has the slightest reason to.

I havent even turned mine on in ten years.

[hrguy54]

I've seen posts about this here before and the only thing I can remember without doing a search is that peroxide is fine for shales and clays but to dissolve limestone effectively you need vinegar or even muric acid diluted 10:1 as long as you're careful enough to stop the reaction before you damage the fossil (sometimes a few seconds).

edit: Good ventilation is critical when using stronger acids.

I've used a weak muriatic acid/water solution for years when cleaning my Ohio horn corals, brachs and even my trilobites. Obviously the key is how long you keep them exposed to the solution. I use a toothbrush to wash my trilos and brachs. Then rinse in water I submerge my corals. then rinse in water. I've been doing it this way for a long time so I feel I have a good feel for it......I'd say practice on some lesser specimens until you get the feel.

[pleecan]

I use ultrasonic cleaner on my Arkona fossils.... from clay pits... works wonders.... and yes one has to be careful....