removing matrix (sandstone/limestone) safely

[OregonFossil]

So, what is the safest way to remove matrix (sandstone and limestone) from calcium shelled fossils. Everything I've read involved acids (some pretty dangerous). What is most ecologically friendly and safest way? I have picks and dramel , but these shells are very thin and almost impossible to remove from the matrix. I am thinking that weaker acids might not work that well and the costs of using more powerful stuff would require a special room with exhaust systems and ways to neutralize the stronger acids to make them environmentally safe. Images are typical of fossils I want to extract.

 

Anyone have a good solution for this issue?

Edited November 9, 2020 by OregonFossil

[oilshale]

Certainly not with acid (whether weak or strong - the difference is only the speed) if the shell is made of calcium carbonate. This will dissolve first and not the sandstone - nothing will remain of the shell.
I would not work on the shell of the snail - I would leave it like this. Nothing to prep there.
With a little patience, you can prep the dentalium with a Dremel and picks.

Edited November 9, 2020 by oilshale

[OregonFossil]

5 hours ago, oilshale said:

Certainly not with acid (whether weak or strong - the difference is only the speed) if the shell is made of calcium carbonate. This will dissolve first and not the sandstone - nothing will remain of the shell.
I would not work on the shell of the snail - I would leave it like this. Nothing to prep there.
With a little patience, you can prep the dentalium with a Dremel and picks.

Thank you, I felt that the acid thing would be beyond my skills and work area tools. And the fact that I am collecting in 3 different areas and have a lot of prep work ahead in the rainy months.

Edited November 9, 2020 by OregonFossil