Preperation Techniques?

[ebrocklds]

i thought that a new topic on preperation techniques could help many of us get the fossils we find looking better.

i also have a question on this very topic.

i have several small and strange fossils from the ordovicain of morocco that i purchased. many of them need more work to be able to identify the specimens. i have done alot of prep on larger things, mainly dinosaurs and mammals and a bit on trilobites, but i have not worked with much small carbonized(?) fossils. i do not think that an air abrasive unit would work for these things. i have tried an aro with some success but i am hessitant as many of the fossil could represent new and or rare species.

what other techniques exist that i could try to remove the fairly soft shale from the fossils? here are a few pics of what i am working on.

this is a marrella like creature

this one and the following are the same. they look like a canadaspis sp.

this last one is a trilobite with a strange colorful preservation.

[Gatorman]

this should be a great topic I know i need to learn alot about prep work

[tomclark]

Yeah, this is great stuff. I'd like to see any info on preparation (except using Gomer's Solution}. I'd like to see what everyone or anyone does to their "matrixed" stuff. Someone on here must have a little mini sand blaster or something like it!?

[ebrocklds]

Tom,

as most of the stuff i find is in matrix, and sometimes very hard limestone matrix, i have aquired many tools and techniques to remove it. (i have only found 1 pleistocene bone in my life!) here is a partial list of some of my techniques, and when i use them.

air scribe (aro)- this is one of the most common tools used in fossil preparation. i use it alot on green river fossil fish, dinosaur bones form the jurassic of wyoming, trilobites that are deep in the matrix, ammonites from the mancos shale in limestone nodules, and pretty much anything that has more that an 1/8th inch of matrix. if you are interested in learning more about the tools check out www.paleotools.com. bill is a great guy and has tried very hard to develop the best tools for the trade. i use a paleo-aro with a long stylus.

Air scribe ( chicago pnuematic) - this is virtually the same thing but larger. i used it alot when i prepared a very big palm frond from the green river formation. i had bill custom make a stylus that was very dull. this way i was able to pulverize the rock just above the paper thin fossil imbedded in the rock. this works well on any fossil that is sturdy and the seperation is good. sharp styluses work well with limestones and other hard rocks.

Micro Abrasive- i love these tools. i have used these blasters for several years and they are irreplaceable. mostly i have cleaned small and delicate trilobites from utah, but i have also cleaned a few from black cat mountain. the last thin layer of shale on fossil fish is also much easier to get off with one of these. i have heard from several differernt echinoid collectors that an air abrasive with baking soda is the only way to clean them. i guess it preserves all the small details without hurting the fossil. also crinoids, bryozoans and brachs clean well with this method. they make several types of powder in different sizes that will clean most any fossil. i use 45 micron dolomite powder. one of the neates things i prepared was a hematitized fenestrate bryozoan that was in sof matrix. when it was done there was many free standin 3-d prepped parts. (tom i just got my mini sand blaster yesterday. i am still getting it ready to use. when it is ready i will be spending alot of time with it . )

Acids and chemicals- although i have not used much acid in prep some times it is a very fast and efficient way to prepare. i use alot of lime-away bathroom cleaner. it is a mild acid that will clean limestone from the fossils. this works essecially well on the pyrite brachiopods and crinoids from ohio. vinegar will often times soften the matrix on things as well. and my favorite chemical WATER. believe it or not water will work very well on alot of things. i used it to clean a 4 foot mosasaur skull from the phosphate beds of morocco. when the matrix got wet you could just take it off with you hand and then wash the mud off the bone. very easy.

well that is all for now but i will add more as i think of them

brock

[ebrocklds]

ok time for another chapter in the book, hahahaha.

alot of time the fossil you are working on break or are very soft. there are many differeing opinions on the correct way to stabilize fossils. this is my opinion and is open to debate.

i generally use one or all of three methods

#1 thin super glue- you are probably all familiar with cyano-acrylate glues. they are great!! but they do have their set backs. the thin glue is great when you have a fossil that is full of tiny cracks and wants to break when you touch it. star-bond, paleobond and other companies produce a very thin glue that will penetrate the tiniest cracks and stabalize them in a matter of minutes. this is great if there is not alot of matrix that still needs to be removed. if you glue matrix onto the fossil you will spend alot of time trying to get it off and often times you will damage the fossil. fortunately these same companies also make a glue debonder. ( i have not used this product personally but i have heard alot of good about it) acetone will also help to soften the glue a little. i try to only use the thin glue when ithere is little risk of getting it on the matrix, but sometime there is no other option.

#2 polyvinyl acetate and similar stabilizers- this is also well known and widely used. varieties are vinac, paraloid, butvar, and several others. i have used vinac for years will great results. these materials are plastic beads disolved in acetone (sometimes alcohol is uses as a solvent) to make a thin mixture. like the thin super glue vinac will penetrate the cracks and even into the pore structure of fossils. when the acetone evaporates the plastic is left behind to strengthen the fossil. this is however much easier to reverse than the cyano-acrylates. the down side is that vinace take s up to an hour to harden. (dry time varies depending on the amount applied, temperature and porosity of the fossil) vinac can also be used as an accent material. for example, elrathia trilobites from utah look much darker when painted with a very thin mixture of vinac. als shells with little contrast can be made to stand out. see pic. and the best part is that it is 100% reversable. i have vinaced fossils and then decided that they looked better before and took it off with a little acetone and a soft tooth brush!

note the partial shell to the left of the highlighted one.

#3 thick super glue- this is mainly for puting things back together. some thick glues will fill a 1/8th inch gap easliy. accelerators will make the glue dry nearly instantly which can be very nice. the draw bakc is that in time anywhere that was sprayed will start to turn green on many fossils. i try my hardest not to ever use this. but sometimes it is the only way. in that case i use a small paint brush to apply the accelerater to the exact spot i want to glue. (the green often doesn't start to show up until weeks after it has been sprayed. i have also noticed that it seems to grow and spread over time. generally it only affects the matris and not the fossil. i mainly use it for casts and thing i know it doesn't change)

more to come,

brock

[geofossil]

I'll put my geologist hat on and 'guess' the matrix is some type of calc-schist... metamorphic limestone like crystalline dolomite. There's not much you can do with it . Usually the fossils are a bit more 3D than they appear but would be destroyed in getting more detail. Acid regimes might help bring out relief. You can cut away a bit of matrix and see how it responds to acetic acid...or hydrochloric acid. I've used acids a lot in freeing specimens (brachs, paleozoic shark teeth, nautiloids,etc) from matrix but the process can be quite exact. The finished products, however can be quite exquisite....fine detail.

As for publications on Moroccan paleozoic fossils. If you live near a university or USGS library then search out a series published in the 1950's (Henri Termeir and others) on 'La Paleontologie Marocaine'. It's published by the Mines and Geology division out of Paris and some of the series continues in post-indepenent Morocco under the the Royaume. i don't know if you read French or not, but the taxonomy, as in all science papers, is in Latin so if you don't it doesn't pose a major hurdle . These papers are also good for some of that generic, unlabeled 'stuff' that comes out of Morocco. If you ever walk the bazaars in Maroco you can buy all types of specimens and I wouldn't trust any info or provenance that comes with them.

(are you sure your Marella-type specimen isn't an Ordovocian graptoloid? Something along the lines of glossograptus . The age, shape and especially the double thecae are charactersitic.)

[ebrocklds]

sorry geo i should have mentioned that the matrix is a fairly soft shale, very similar to the Utah cambrian wheeler and marjum formations. ( a bit softer and not as defined cleavage) also i think that the fossils if exposed to liquid would come right off the rock . they are a film much like the pennsylvanian ferns from st. clair penn.

as far as the "marella" goes i am not sure. i would bet that they are not graptoloids because i have several that are the same size and shape, never with more or less "appendages" and always arranged identically. i was also told by the dealer i bought them from, who is also a good friend, that they were marella like fauna. it wouldn't surprise me as there are several other pieces in the collection the resemble other burgess stuff. i am not ruling anything out, just explaining my reasoning for calling it marella.

thanks a ton for the publication info. i will have to go the the local university and try to find it. i speak spanish so i am usually pretty good and figuring out what is being said in french. if not i can find a friend that speaks french and make him translate

thanks

brock

[Desmond]

I'll add to the acid bit just from trial 'n error experiance

Rule #1 Use the smallest container the fossil will fit in.

#2 Use the cheapest 5% acetic acid vinegar you can find (then you can do what you want)

#3 Dilute 50% with water

#4 Soak 1-24 hr but not longer the reaction slows down but proceeds as long as the fossil is soaked

#5 Using a soft brush (I like children's paint brushes that come with every kids water color kit) wash the fossil in a container of water between treatments

#6 And most important (mainly because it's often forgotten) once complete, soak the fossil in baking soda and water (about 1 tsp / cup) for 24hrs then in plain water for an hour.

That all is for preping a fossil out of soft matrix only

If you are extremly careful (think obsessive) you can use muriatic Acid for rapid removal of material.

DO NOT use this ON the fossil itself it WILL damage it badly (like I said trail and error.)

If you use strong acids be sure to use them out side with a breeze the fumes WILL cause you harm!

And neutralize them with lots of baking soda!

As always if you see anything I'm missing add it Please!

[ebrocklds]

thanks desmond, i have done very little acid prep and it is something that i would like to try more of. it will open a whole new world of fossil prep. i can already see the fantastic tiny skeletons prepped in 3-d !!! :lol:

[Uncle Siphuncle]

Guys

Here is something I wrote recently and the Dallas Paleo Society printed it in their newsletter last month.

Echinoid Preparation:

One Collector’s Perspective on Tools and Techniques

By Dan Woehr

I’ve prepped a few echinoids since I embraced the collecting lifestyle 4 years ago and in the process have learned some prep techniques from other people that I’d like to share. Taking things a step further I’ve put together a legend of what techniques work best for echies by formation. Hopefully this will help other folks to bring maximum aesthetic beauty out of their finds. The basic techniques I employ are as follows:

• Method A - Brass brush and water – Cheap, easy and mobile, this method works well on soft matrix. I’m often seen brushing echinoids on my tailgate or a picnic table during lunch hours to leave time for garage based prep in the evenings. Brass is soft enough that it doesn’t scratch the echinoid test. Don’t substitute a stainless steel brush or you’ll end up with unsightly scratches and obliterate minute detail. The stiffer brushes I use most of the time are found with the welding equipment at Home Depot. Sometimes I use the softer ones from Lowe’s for more delicate fossils.

• Method B - Air scribe – I have two, a Chicago Pneumatic knockoff called by Paleotools called the ME-9100 and an ARO scribe. The ME-9100 is my workhorse which does most of the gross work. The ARO is used for fine detail work. I think I paid about $250-$300 for each once they were set up how I wanted them. I’ve equipped each with a long stylus to allow me to work nearly parallel to the surface of the specimen without pecking holes in the surface. I generally use the scribe to remove most of the matrix, leaving just a veneer which is then removed by one of the other methods described in this article. I use this method in open air rather than in a blast cabinet so I can see what I’m doing better, but run a fan behind me to blow the dust outside and wear a dust mask as well.

• Method C - Microblaster – I use a low end blaster called the Eco Blaster from Crystal Mark. It cost me about $450 and consists of an air hose, media canister, foot pedal, and pencil tip handle which accepts screw on orifices. This system does not allow control of media flow but most of my work is gross blasting so this is not a problem. I generally set my compressor at 125 PSI and blast away. I use an orifice size of .060 inch 90% of the time and .030 for delicate work like cleaning between Archaeocidaris spines. I use baking soda as media 90% of the time and occasionally switch to dolomite for more tenacious matrix. I work in a low end blast cabinet from Harbor Freight to which I’ve hooked up a shop vac as a dust collector. Periodically I recover media from the cabinet and shop vac, sift it through a cheap frying pan splatter screen, and reuse it. Drain off the water from your compressor tank often or it will clump your media. Better yet, on humid days put the compressor in the laundry room (if your wife will allow it) and run a hose out to the garage as air conditioned air has already had the moisture pulled out of it.

• Method D - Potassium hydroxide (KOH) – This stuff is caustic so wear goggles and gloves and use it in a ventilated area (again I run the fan over my work area and out the garage). KOH is available in flake form from chemical supply houses in 5 pound plastic bottles to 50 LB bags. Keep the stuff sealed as it is hygroscopic (readily absorbs moisture). Basically I put echinoids in an old Pyrex dish, spray them with atomized water to help the flakes stick, dump the flakes on them to cover all the unwanted matrix, spray them again, and check them every 20-30 minutes, flipping them as required. KOH creates an exothermic (heat releasing) reaction with water that turns certain forms of calcareous matrix to sludge. It is possible to overcook your echies, creating microcracks and a bleached surface with reduced detail so watch the time. I tend to wash them off after a while, scribe a little more matrix and repeat the KOH application as required. A gelatinous, caustic slime will cover the specimens so I scrub them under the hose with an old plastic brush while wearing gloves them drop them in vinegar for 10-15 minutes to neutralize the KOH, and after another water rise they are finished. Keep in mind that in some formations KOH attacks the test.

In my experience the following methods are most appropriate for echinoids from the Texas formations listed below (all formations are Cretaceous except as noted):

Formation Recommended Methods

Beaumont/Ingleside (Pleistocene) A-Good luck with this cemented sand

Corsicana A, B, C

Pecan Gap A, B, C

Anacacho A, B, C, D

Sprinkle A, B, C, D

Austin A, B, C, D

Grayson A, B, C, D

Georgetown A, B, C, D

Mainstreet A, B, C, D

Weno A, B, C, D

Boracho B, D

Fort Worth/Duck Creek A, B, C, D

Goodland A, B, C, D

Walnut/Comanche Peak A, B, C

Glen Rose A, B, C

Winchell (Pennsylvanian) C

Again this is just the personal experience of one guy who really doesn’t have the tenure of some of our more seasoned members, so I’d be interested in hearing of any other time saving, detail preserving techniques out there.

[Desmond]

I forgot to add one thing to the acid post I had above...

Because you want the least acid volume to cover the fossil I use plastic bb's to fill voids and reduce the acid volume in whatever container is the closest fit. I found them in bulk at a rock tumbling store...