Abrassion tools

[oldtimer]

I am a new member here and have been reading about fossil prep. I have an air scribe but am looking for other tools and techniques needed to prepare my finds.  I have seen the abrasive techniques

used in videos and reading here on the forum.  My question is what should I be looking for in an air abrasion.  What tools are needed and what kind of media is used?

[Kane]

That very much depends on the kinds of fossils you are preparing, and what kind of matrix they are set in. Ideally, you want to ensure your blasting medium is a bit harder than the matrix, but softer than the fossil to avoid damaging it. 

 

I know for the fossils I work on, I alternate between good old fashioned baking soda (baked in the oven to remove any moisture that could clog up the air abrader) and dolomite at about 40 microns. These two are good for a range of shales and limestones - at least for me.

 

Other folks who have much tougher matrix to work with have used tougher media like aluminum oxide.

 

Speaking of the tools, your air abrader (or air eraser) is a finishing touch kind of tool once you've blasted away a lot of the bulk matrix. I personally use a Paasche Air Eraser, but there are others out there. With a tool like that, you will be running your air compressor at probably not much higher than 40 psi. To ensure good air flow, use teflon tape around any of the hose connections, and for good blast medium flow in the air eraser to prevent clogs, use a water trap. 

 

It may be a good idea to also invest in thin dispensing needles for very precise work (about 18 to 22 gauge), a stereo microscope to see what you're doing up close, and to always protect your lungs by operating in a blast box with some shop vac suction. You might be better off building your own rather than buying a blast box since a lot of those ones you can get online or in stores tend to be a bit too small for fossil prep work. If you do a search for "blast box" here, @Malcolmt has a great blueprint and instruction document that, in the end, will probably cost you less money than purchasing an already manufactured box.

 

But perhaps also very important is to experiment first on stuff you don't mind ruining! Patience is also key as nothing can destroy a fossil faster than impatience.  

[oldtimer]

Thanks for the advise.  All that you say is very understandable.  I kind of figured to work on things first that I did not care if they got damaged.  Yeah, I have done that.  I know there is a learning curve and patience is key.  I have been doing work with the scribe and learning the different techniques based on the matrix composition and gaining the understanding of it's use. I have been using hand tools and such to do finer work and now see the use of an air  abrader could help out on detail work. 

 

My goal is to learn how to make specimens worthy of professional displays. 

 

Compressor needs are not a problem.  I already have one used in business that is more than capable with a water trap and filter. And building a blast box sounds like a fun project and I probably have all the materials needed in the shop.  Thanks for all the tips.

 

 

[jpc]

Also, if you have a compressor that uses oil, as opposed to an oil-less one, you will have to get a coalescing filter to get the excess oil out of the air lines before it goes to whatever air abrasive you use.  

[oldtimer]

Fortunately mine is an oil-less.