Wrangellian Posted October 6, 2015 Share Posted October 6, 2015 (edited) This specimen seems to be covered in some sort of natural limey scale, but looks like it would look great if it could be removed. I can pop it off by hand with a needle/pin, bit by bit, but it's tricky to not puncture the fossil itself. Do any of you preppers have any experience with this type of coating, and can it be removed with any ease (whether with simple tools or expensive air tools that I don't have), without abrading the fossil surface underneath? In any case it's probably not going to be done by me, but if I knew what anybody was capable of I would have a better idea of what to do with this piece, ie. keep it, pass it on, sell it (and at what price), etc. Thanks in advance Bottom of piece to show hardish platy sandstone matrix. I'm not sure the fossil itself is as resistant damage as this side would be, though. I guess it would be a case of 'try it and see'. Edited October 6, 2015 by Wrangellian Link to comment Share on other sites More sharing options...
Wrangellian Posted October 6, 2015 Author Share Posted October 6, 2015 Another pic (fluor. light) Here is a pic from the web of another specimen which has less scale on it, that might give an idea of what mine would look like if the stuff could be removed: Link to comment Share on other sites More sharing options...
Ludwigia Posted October 6, 2015 Share Posted October 6, 2015 The coating itself wouldn't be the problem, but rather the consistency and type of preservation of the fossil surface immediately under it. I can't really tell from the photos if there's shell substance there or if it's just a mold, in which case the connecting layer could be "sticky", making it hard to get it off without afflicting damage to the fossil. Depends also on how soft or hard the fossil is in relation to the coating. Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
Mike Pocock Posted October 6, 2015 Share Posted October 6, 2015 Looks like it would be a delicate job of prep Link to comment Share on other sites More sharing options...
RJB Posted October 6, 2015 Share Posted October 6, 2015 Im just glad its not me having to face that prep job. Looks like a tuff one. Im going to wish you the very best of luck. RB Link to comment Share on other sites More sharing options...
FossilDAWG Posted October 6, 2015 Share Posted October 6, 2015 The scale looks (as far as one can tell from a photo) as if it may be some sort of carbonate deposit. If so, it may be removable with dilute acetic acid, basically vinegar. Usually sandstone is impervious to such treatment, if so the fossil would not be affected. You could try some vinegar on a part of the matrix away from the fossil and see if it dissolves or loosens the crust (so it can be easily flaked off) before risking treating the actual fossil. Don 1 Link to comment Share on other sites More sharing options...
Wrangellian Posted October 7, 2015 Author Share Posted October 7, 2015 The coating itself wouldn't be the problem, but rather the consistency and type of preservation of the fossil surface immediately under it. I can't really tell from the photos if there's shell substance there or if it's just a mold, in which case the connecting layer could be "sticky", making it hard to get it off without afflicting damage to the fossil. Depends also on how soft or hard the fossil is in relation to the coating. There is no shell surface, it's basically a sandstone mold. The bits that I have popped off don't seem to have pulled anything off the fossil surface, but as I mentioned, it's hard to poke them off with a needle without poking into the fossil surface when the scale gives way. The scale looks (as far as one can tell from a photo) as if it may be some sort of carbonate deposit. If so, it may be removable with dilute acetic acid, basically vinegar. Usually sandstone is impervious to such treatment, if so the fossil would not be affected. You could try some vinegar on a part of the matrix away from the fossil and see if it dissolves or loosens the crust (so it can be easily flaked off) before risking treating the actual fossil. Don Is there not also some carbonate holding the sandstone grains together? I might try it and get back to you. Link to comment Share on other sites More sharing options...
Wrangellian Posted November 8, 2015 Author Share Posted November 8, 2015 Well I tried the diluted vinegar idea and it came out not too bad. There were some loose grains left over but that was probably inevitable (they may have been attached mainly or only to the calcite) but I'm still not sure that the fossil surface is not a little bit 'weathered' by the treatment, and that an airscribe treatment applied directly to the calcite would not have been better. But this was certainly easier than the tedium that would have entailed (and the cost which I would incur, as I don't have an airscribe)... Link to comment Share on other sites More sharing options...
FossilDAWG Posted November 8, 2015 Share Posted November 8, 2015 It seems to have come out quite well. Looks good! Don Link to comment Share on other sites More sharing options...
Wrangellian Posted November 8, 2015 Author Share Posted November 8, 2015 Thanks for the recommendation, Don. It was not easy but I took it carefully. Link to comment Share on other sites More sharing options...
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