Consolidating wet fossils

[dingo2]

So last year I got around to consolidating the fossils in my collection with paraloid B-72. I used a 4% concentration by volume. Unfortunately when doing this, I missed what I've since seen some call a crucial step, and that is to ensure that each fossil is sufficiently dry before consolidating.

 

My question is, how massive of a mistake is this, and how one would go about correcting this. From my understanding, the theory is that the plastic traps the water inside the fossil which causes it to rot from the inside out. How long does this process take to occur? I havent had any fossils breaking apart in the meantime. I would think that since acetone is miscible in water, any water that is inside the fossil would have mixed with the acetone during the dipping process. 

[Harry Pristis]

Residual moisture may cause a white film to develop on the surface of a fossil after dipping in the consolidant.

 

Here's how the white film forms: As the acetone in the consolidant evaporates, the temperature at the surface of the specimen chills abruptly, lowering the dew-point at which ambient water vapor condenses.

 

And, that's my theory -- that the white film has two potential sources: residual interstitial moisture and ambient humidity condensing at the surface chilled by evaporation.

 

Think about a plastic bag of food placed into a freezer, where moisture turns to frost and the bag is the film of consolidant. Frost can form on either or both sizes of the plastic bag, inside frost from moisture in the food and outside frost from atmospheric moisture.

 

My solution is heating the specimen to drive off residual moisture, and consolidating while it is warm to increase the dew-point at the specimen's surface, inhibiting condensation as the acetone boils off.  I use an infra-red lamp to  heat the specimens.

Do NOT heat the acetone solution directly. The acetone solution will get warm after dipping a number of heated fossils. You must have good ventilation to deal with the fumes!

[dingo2]

So my issue is a little more severe than just some residual moisture on the surface. Some of the fossils I consolidated were cleaned with water shortly before being dipped. I dont see this white film on any of the fossils I've dipped though. What I'm asking is this: is there any legitimacy to the notion that consolidating wet fossils can cause them to rot from the inside out, and if so, what it the timeframe for this process? I assume if its something that I should be concerned about, I should be finding fossils broken in half occasionally when I pull them out of a drawer. As of yet, I havent seen anything of the sort.

 

I'm not crazy about the idea of soaking everything in acetone again to get the moisture out if it is indeed stuck in there, because some of the stuff I consolidated is large and will take a lot of acetone to undo. 

[Al Dente]

5 hours ago, dingo2 said:

is there any legitimacy to the notion that consolidating wet fossils can cause them to rot from the inside out, and if so, what it the timeframe for this process?

I sometimes consolidate fossils with vinac in acetone while the fossils are still wet. The reason why I do this is the fossils are very fragile and filled with clays that will expand and break the fossils if allowed to dry before being consolidated. I don’t believe this creates an airtight seal that prevents the water from evaporating. I don’t think the vinac penetrates very much when the fossil is wet. I usually soak the fossil overnight in the solution if the fossil is wet and fragile.

 

I don’t think you need to worry unless there is pyrite in your fossils.

Edited April 11, 2023 by Al Dente

[Harry Pristis]

What I'm asking is this: is there any legitimacy to the notion that consolidating wet fossils can cause them to rot from the inside out, and if so, what it the timeframe for this process?

 

No, no legitimacy.

[hadrosauridae]

Fossils are mineral replacement, it is impossible for them to "rot".  Best option is to allow your fossils plenty of time in a warm, dry place to completely dry before consolidation. A standard incandescent bulb ind  desk lamp can help a lot.

 

Moisture in your fossil does more than just cause unsightly white residue.  IT will cause the consolidate to instantly set, so a damp fossil will not get consolidate penetration and stabilization that your expect, it will set in the immediate outer layer only. 

 

There are some consolidates that dissolve in water and those would be a good choice for a damp specimen if you can't wait for it dry, or if drying will cause it degrade.  

[FranzBernhard]

13 hours ago, dingo2 said:

is there any legitimacy to the notion that consolidating wet fossils can cause them to rot from the inside out

Are you possibly talking about pyrite or marcasite disease?
Franz Bernhard

[dingo2]

31 minutes ago, FranzBernhard said:

Are you possibly talking about pyrite or marcasite disease?
Franz Bernhard

No, rot was not a great word for what I'm referring to. I am simply concerned about any sort of degradation that can be caused by water trapped inside of a fossil (assuming that is indeed what happens when you consolidate a wet fossil, which does not seem to be the case).