How to remove salt water

[Jurassicz1]

So i got alot of fossils from sweden from the ocean altough i dont remember if its salt water or not. But if it is how do i remove it? heard that it slowly destroy the fossils from the inside what can i do? Im also going to put glue on one of the finds is that going to mess up when i clean the salt water? 

[Kane]

I have not heard about saltwater damaging fossils. I suppose you could immerse the fossil in regular water which would dilute the salt content?

It might be helpful to show us a picture of what you are dealing with.

[TqB]

Salt from sea water does damage fossils with Cretaceous Chalk matrix and they can disintegrate. I don't have much experience of it but long soaking (days to a couple of weeks I think) in several changes of fresh water is recommended, then slow drying. Not sure about the glue but it should usually only be done dry - depends on the fossil and type of glue though.

 

Other limestones may not suffer - I've had no problems with Palaeozoic and Jurassic material from the coast.

Edited September 5, 2020 by TqB

[Bobby Rico]

I have removed salt water from some North Sea Brown Bank finds. Soak in fresh water for about 3 days and change the water every day. I also dry the fossil very very slowly. 

[Jurassicz1]

1 hour ago, TqB said:

Salt from sea water does damage fossils with Cretaceous Chalk matrix and they can disintegrate. I don't have much experience of it but long soaking (days to a couple of weeks I think) in several changes of fresh water is recommended, then slow drying. Not sure about the glue but it should usually only be done dry - depends on the fossil and type of glue though.

 

Other limestones may not suffer - I've had no problems with Palaeozoic and Jurassic material from the coast.

Oh how do i know the age ? I dont know what location they came from

[Kane]

Can you post a picture of them?

[darrow]

I often collect from a marine environment and developed the method below using a salinity meter to monitor and trend salts as they defuse out of a specimen.

 

1. Submerge the specimen in a volume of fresh water at least 5x the volume of the specimen.
2. Soak specimen for 14 days replacing the fresh water every 24 hours.
3. Remove specimen and allow to air dry.

The volume of water relative to the volume of the specimen maters.  The larger the volumetric ratio of water, the steeper and longer lasting the diffusion gradient will be and the faster the salt will be removed from the specimen.  Too small of a volume of water and you could reach equilibrium halting the diffusion of salts out of the specimen well before the next 24 hour water refresh.  

 

This size of the specimen the degree and type of fossilization, the specimens shape and its volume to surface area ratio will all influence the speed at which the salts can be coaxed out of the specimen.  The method above has worked for for the shoe box size and smaller Pleistocene age specimens I collect on the upper east Texas Gulf Coast.   Larger specimens could take longer, perhaps much longer.  If you're often dealing with larger specimens or ones of potential scientific value you may want to invest ~$300 in a salinity/conductivity/TDS meter so you can monitor the progress of the desalination process.

[hadrosauridae]

I would probably give it much longer than 2 weeks for desalination treatment. I know that shipwreck artifacts can spend years in freshwater tanks.

 

the problem with salt absorption is after it dries.  The salt will form crystals as it dries, and the crystals act as seeds to attract more salt solution to attach too.  The result is a specimen that basically "explodes " in slow motion.  The mineral substrate plays a large role in this also (as far as how much salt it might absorb from the water)

[Jurassicz1]

23 minutes ago, darrow said:

I often collect from a marine environment and developed the method below using a salinity meter to monitor and trend salts as they defuse out of a specimen.

 

1. Submerge the specimen in a volume of fresh water at least 5x the volume of the specimen.
2. Soak specimen for 14 days replacing the fresh water every 24 hours.
3. Remove specimen and allow to air dry.

The volume of water relative to the volume of the specimen maters.  The larger the volumetric ratio of water, the steeper and longer lasting the diffusion gradient will be and the faster the salt will be removed from the specimen.  Too small of a volume of water and you could reach equilibrium halting the diffusion of salts out of the specimen well before the next 24 hour water refresh.  

 

This size of the specimen the degree and type of fossilization, the specimens shape and its volume to surface area ratio will all influence the speed at which the salts can be coaxed out of the specimen.  The method above has worked for for the shoe box size and smaller Pleistocene age specimens I collect on the upper east Texas Gulf Coast.   Larger specimens could take longer, perhaps much longer.  If you're often dealing with larger specimens or ones of potential scientific value you may want to invest ~$300 in a salinity/conductivity/TDS meter so you can monitor the progress of the desalination process.

Oh ok thanks But whats volume with the water and rock and should i do it in flint or all fossil rocks can u do it with all kind of sizes of the fossils? And should i also do it with sea urchins? Or should i do it with all my finds from the sea?

[Jurassicz1]

6 minutes ago, hadrosauridae said:

I would probably give it much longer than 2 weeks for desalination treatment. I know that shipwreck artifacts can spend years in freshwater tanks.

 

the problem with salt absorption is after it dries.  The salt will form crystals as it dries, and the crystals act as seeds to attract more salt solution to attach too.  The result is a specimen that basically "explodes " in slow motion.  The mineral substrate plays a large role in this also (as far as how much salt it might absorb from the water)

Ok so 3 weeks? And can i place in some fossils in or Only one? Can i just use bowls? And when i change the water should i take the fossils out or just take the water out or just put new water on the older water?

[hadrosauridae]

Just drain off the old water and replace with fresh water.  How long it takes depends on the fossil. It doesnt matter how many fossils you soak.  Bowls are fine.  The only true way to test is to check water salinity after soaking.

[Jurassicz1]

12 hours ago, hadrosauridae said:

Just drain off the old water and replace with fresh water.  How long it takes depends on the fossil. It doesnt matter how many fossils you soak.  Bowls are fine.  The only true way to test is to check water salinity after soaking.

Ok do i need to do it with sea urcins and flint or all fossils in general?

[pachy-pleuro-whatnot-odon]

7 hours ago, Jurassicz said:

Ok do i need to do it with sea urcins and flint or all fossils in general?

I'd do this for all finds from a marine/saline context.

 

The main thing to keep in mind here is there's a balance between the porosity of the fossil, the salinity of its initial environment, duration of exposure, and salinity and humidity of the air in the target environment (i.e. natural salinity of the air where you live). That is, the more porous the fossil is, the more salt it can potentially suck up/contain. This generally means that the older the fossil/sediment, the less salt is an issue. However, as duration of exposure to the saline environment is also a factor, the longer a fossil has been exposed, the more time it has had to pick up salt and, thus, the more salt it can contain... How much salt a fossil will contain is therefore a factor of its porosity (how much it can contain), how long it has been exposed to the salt, and how much salt it was exposed to per unit of time (not all marine environments are equally saline).

 

To remove the salt, you need to soak the fossil in a volume of water that has a significantly lower saline degree than the fossil itself. That means you can use rain, tap or demoralised water to coax the salt out, and - depending on how valuable the fossil is to you - might move from water with higher salt content to water with lower salt content - e.g. tap water to demineralised (this is a strategy to reduce water waste and/or expenses). Moreover, the greater the volume of water, the longer it will take for an equilibrium to build between the water and the fossil. So, the less saline the water or the greater the volume of water, the longer you can wait between subsequent refreshes. This also means it doesn't matter how many fossils you put into the water simultaneously, as this will just mean the equilibrium will be reached sooner. I.e. just use less saline or a greater volume of water, and this will even out the issue.

 

As to the frequency of bath changes and the overall duration of desalination, that depends on the initial salinity of the fossils, as described above. Also keep in mind that, as long as you don't coat or consolidate the fossil, you can always repeat a desalination treatment further down a fossil's lifecycle. That is, whenever you observe salt-bloom popping up, you can repeat the treatment. Keeping relative humidity stable will also help stabilise salt-creep, but may be a bit excessive for most specimens.

 

Hope this helps!

[pachy-pleuro-whatnot-odon]

Some further worthwhile pointers are that some people use their toilet's container of flush water as a renewable water-source for desalination, as the water gets refreshed everytime the toilet is used, and that you should always make sure the fossil has had time to completely dry inside and out before applying a coating or consolidant. Drying in itself should progress slow and gradual, so as not to damage the integrity of the specimen, but not so slow as to cause potential detrimental effects by the fossil remaining moist.

[FossilDAWG]

2 hours ago, pachy-pleuro-whatnot-odon said:

Some further worthwhile pointers are that some people use their toilet's container of flush water as a renewable water-source for desalination, as the water gets refreshed everytime the toilet is used...

I had not heard of that, but it's a great idea!

 

3 hours ago, pachy-pleuro-whatnot-odon said:

... or demoralised water ...

Do you mean demineralized water?  Or distilled water?

I'd worry that demoralized water would make for depressed fossils.

 

Don

[pachy-pleuro-whatnot-odon]

6 hours ago, FossilDAWG said:

I had not heard of that, but it's a great idea!

 

Do you mean demineralized water?  Or distilled water?

I'd worry that demoralized water would make for depressed fossils.

 

Don

 

Well, demoralised water has been basically written off by the rest of the world, so is easy and cheap to come by

No, I meant demineralised water. Always demineralised when desalinating, as it has the greatest absorption capacity. Seems an incorrect auto-correct managed to slip by me after all

[FossilDAWG]

We have all been the victim of autocorrect I think.

 

Don

[Jurassicz1]

On 9/6/2020 at 2:49 AM, hadrosauridae said:

Just drain off the old water and replace with fresh water.  How long it takes depends on the fossil. It doesnt matter how many fossils you soak.  Bowls are fine.  The only true way to test is to check water salinity after soaking.

Ok how do i check water salinity? I will be using tapwater. And should i do it for 2-3 weeks like some said? Or can it be just a few days?

[pachy-pleuro-whatnot-odon]

54 minutes ago, Jurassicz said:

Ok how do i check water salinity? I will be using tapwater. And should i do it for 2-3 weeks like some said? Or can it be just a few days?

As I understand there are special salinity metres (i.e. devices) out there, which you could use to see if your fossils have been properly desalinated. Keep in mind, though, that the salt level will never drop below that of the tap water you're using, and that the less salt is left in your fossil the more time it will take to extract. In other words, salinity of the water used to desalinate your fossils will increase with time. And even though it may seem stable, it could just require more time for the salt to come out. So, I think that even with a salinity metre it'll be difficult to determine when you're actually truly done desalinating. In my opinion it's always a best-estimate and in part based on experience - both in a general sense and in the material you're dealing with.

 

I personally just let my fossils (mostly small ones) soak in three subsequent baths for a couple of hours at a time. I never take more than a few days for it. But that's mesozoic marine fossils, which are generally denser and take up less salt than terrestrial and younger fossils. My approach seems to have worked fine for most of my stuff. Just fossil wood can be a bit tricky to preserve. And as I rarely impregnate these fossils with a consolidant, it's easy to monitor them and give them a renewed treatment if necessary. Even museums need to continuously monitor and preserve their collections...

[LabRatKing]

There are a couple of different ways to "neutralize" chloride salts. The fastest, easiest way is with RODI, that is ultra pure reverse osmosis/deionized water...however unless you work in a lab you likely won't have access to this.

 

The good news is regular old DISTILLED water will work well too.

 

Now the downside to this is both of these WILL affect soft chalky substrates. For hardcore folks, this means ion exchange is going to be necessary, but this really isn't an option for most folks either, and can affect the fossil itself because you are forcing chlorides to change places with something else. In the case of sodium chloried calcium hydroxide can be used, but I do not reccomend it as that is some caustic stuff.

 

Personally, for the few fossils I own that have this issue, I just display them in antique glass jars filled with distilled water. Sure, have to change the water every so often, and perhaps a bit of ethanol or methylparaben to keep the mold out.

 

As others have mentioned, many oceanic artifacts are always kept in liquid due to the destructive nature of crystal formation.

 

I have a few urchins that I sealed in clear resin, ensuring they stay clean and damp for eternity, but are still easy to look at, handle, and enjoy.