[meteorite-list] Hard to Polish Meteorites - Any Ideas? (diamond grit sandpaper?)
From: Adam Hupe <raremeteorites_at_meteoritecentral.com>
Date: Sun, 30 Oct 2011 07:29:33 -0700 (PDT)
Sorry, it took so long to get back to you on this.? I just got back from a grueling Mojave Desert meteorite hunt which I will get into later.
Thank you for the compliments.
There is no real secret to good meteorite preparation. I learned the hard way just like anybody else.? I found that with time and experience the end product will become better.? My experience comes from preparing over 20,000 terrestrial rocks, over 35,000 meteorite specimens and in excess of 10,000 hours on the equipment.??
Although I have lapidary saws ranging from 4" to 24", I find that my 8" saw is used the most. There is no particular saw blade supplier I like the best and have tried just about every brand available. I avoid cheap Chinese made blades and polishing disks at all costs having had one shatter on me.? This brings up an important issue. Always wear safety goggles and use the plexiglass glass shields that come with the equipment. ? On larger cuts, I find that older well-maintained machines like a Highlands Park do a much better job and are built to last a lifetime.? Hydraulic feeds are the best followed by gravity, then worm gear and finally freehand.? I freehand a lot of the smaller pieces using a rail and clamp system because I like to feel the work and know when the blade is beginning to bind. That way, if I run into a large piece of metal, I can slow it down.
The secret to a good finish is to use every grit until you reach the desired polish.? It is important to clean the equipment between grit changes.? When approaching the final polish, I continually rotate the piece manually as it is being ground so that there are no swirl marks left by the polishing unit.? Do not waste your time with a automatic gravity feed polisher as it will take 8 hours whereas the same task can be completed by manually holding the piece in less than a half hour including grit changes.? Wear a mask when polishing as the vapor coming off of the polisher is not good to breath.
Finally, I mostly use distilled water as a coolant but will use kerosene or mineral oil if a situation calls for it.? Some meteorites have water soluble minerals in them like E-Chondrites and Aubrites.? I never dry polish other than metal meteorites because I do not care for the dust which you can taste for days sometimes once it imbeds itself in your sinuses .? ??
Gotta go, I hope this is helpful.
Received on Sun 30 Oct 2011 10:29:33 AM PDT