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randyjaco
06-27-2011, 09:10 AM
I picked up a couple of large ammonite pleurocera fossils at a flea market. I have seen these in museum stores that appeared to be polished or coated with something shiny that looked very nice. Is there anyone who knows the process
for fixing them up for display.

TIA

Randy

Duffy
06-27-2011, 09:16 AM
I think that you may be out of luck. Whether the fossils have that shiny "nacre" coating is dependent upon where they were fossilized. For example, the ones found in Alberta are quite famous for the opal-like coating, while others seem to look like fancy mudstone.

PTSideshow
06-27-2011, 10:03 AM
As been said it will depend on the location and the matrix they are in. The polished ones are mostly from Madagascar and Indonesia . Most of those are mineralized with quartz type minerals. Which will take a nice polish if the matrix is a soft shale or dried mud crumbly that will not take or hold a polish. If it is a harder material it will also take a polish. You can always try on the back side.

They do infuse the softer matrix's with glues and binders to hold them together. CA adhesives thin is flowed over the surface, in a vacuum to pull the adhesive into the surface. A thinned clear drying white glue will work too.

It has been around probably form the Jurassic period. other than being keep out of the elements so it doesn't weather, no action is required.

As to polishing them so the surface is shinny. It is a multi step process that you will have to do a search for polishing cabochons or slabs. It can require a lot of equipment $$$$$.

It is possible to work and polish some fossils and minerals with shop tools as their hardness is lower than tool steel.
I have polished some slabs with a pneumatic sander, and assorted automotive papers while doing them wet in a pan of water, or a pan with a sponge so you can keep the stone wet. the application of water is mostly to flush the grit away.
I'm sure doing a google search will give you a lot of info on polishing stones, when done a coat of good paste wax or auto acrylic wax will work.

randyjaco
06-27-2011, 01:07 PM
Yeah, these are pretty soft. They came out of Mexico.
How about varnish or shellac? They are not going in a museum or anything and I have a whole 3 bucks invested. I'd just like to have them look a little nicer. They are pretty good sized and could make a good display. They are just dull.

Thanks for responding.

Randy

PTSideshow
06-27-2011, 06:23 PM
If the area around the fossilized object is real soft, use a soft longer hair brush to gently clean and remove any extra dirt and dust. On the fossil it self you can try using a rag wet with some dish soap. Dawn isn't only the best for removing greasy and oily stuff from birds and dishes. It works on lots of other stuff too. You then can rinse it with a different clean wet cloth and then pat dry.

How about varnish or shellac? Shellac will yellow, and some of the clears tend to discolor over time.

Some of the best stuff is the cheap plastic high hold hair spray. Used it all the time as a fixative in making cartoons for signs and stained glass layouts when I used chalks and charcoal. Have a copy that are over 20 years old and it is still holding.

I would go with a non yellowing rattle can clear in your choice of gloss or satin.

To keep the matrix from crumbling make up a box to hold each one. So you don't have to pick it up by the matrix.

Another cheap trick is get the plastic food storage containers that are a good fit trim the height down, if you don't want to close the container for storage keeps the dust off. You can paint the container with the new plastic rattle can paint.

aboard_epsilon
06-27-2011, 06:26 PM
think i would put wax on them ..the type you use on wood bowls..then just polish up ..

all the best.markj

KiddZimaHater
06-27-2011, 07:57 PM
DON'T DO ANYTHING !!!
For pete's sake, you're gonna ruin that fossil with shellac, plastic, varnish, or buffing. Just clean it up with water and a clean rag, and let it sit in it's natural state.

ed_h
06-27-2011, 09:19 PM
I bought a good sized (4-5") trilobyte fossil from a vendor at the AGU show in San Francisco one year. I believe it was $150 or so. The fossil itself was very nice looking--shiny black in a grayish matrix. The guy I bought it from admitted to me that the shiny black substance was shoe polish.