Special Grease Used on Pallasites
Posted 22 September 2013 - 03:55 PM
I just bought 2 pallasites and the shipper said they would be coming with a "special grease" on them to protect them in shipping. This grease can then be removed with alcohol. Does anyone know if using this grease is common for protection and would I just use rubbing alcohol. What type of grease is used?
Posted 22 September 2013 - 08:22 PM
Rubbing alcohol is usually 70% to about 90% alcohol, the remaining percentage is water. Of course, you might try to obtain pure isopropyl alcohol (same as rubbing alcohol, but no water) and go that route.
I wonder why the seller saw fit to coat them with this "special" grease? Perhaps these are known rusters, and that might be why.
IIRC, Glassthrower has great experience with cutting iron meteorites and perhaps he can share his best practices. I would wait until he chimes in before trying anything.
Posted 22 September 2013 - 08:27 PM
Posted 22 September 2013 - 08:46 PM
Posted 22 September 2013 - 08:51 PM
I emailed the seller to see what alcohol he recommends.
Posted 23 September 2013 - 08:24 AM
Posted 23 September 2013 - 09:18 AM
The main problem I see with the grease is that's it lacks the penetrating properties needed to keep moisture from the interior. It no doubt does a good job of maintaining the polish, but that's it. Pallasites are no more or less prone to rust than irons in general, but the corrosion can be much more objectionable since it can eventually loosen the olivine from the nickel-iron matrix. Once that level of degradation occurs, it's nearly impossible to reverse.
The good news is that the polished surface is much easier to maintain than one that is etched. If the metal shows fingerprints from handling, or a dulling of the polish, conventional metal polish and a soft cloth can restore the mirror-like appearance. Additionally, I would avoid any alcohol other than anhydrous. There is no need to introduce water into a meteorite, especially a pallasite where it can migrate into the microscopic spaces around the olivine. Also, typical rubbing alcohol can contain glycerine, which while not damaging in itself could inhibit proper drying. The best method of grease or oil removal is acetone, which while it may penetrate into any cracks, will evaporate quickly. If it leaves a dull film behind, simple metal polish and cloth will restore the mirror finish. In any case, a protective metal polish should be used regardless of the method of grease removal.
The other good news is that properly prepared Brahins should remain rust free without any serious precautions. I know these are relatively expensive, so I wouldn't want to encourage experimentation, but I would treat these with gun oil as well. In the case of a polished surface though, it's the penetrating property that is desireable. After allowing sufficient time, I would remove the oil from the surface and apply a metal polish designed for iron or steel. 'Flitz' is one that I've had good sucess with.