Meteorite Preservation and Repair
How to Preserve Meteorites
Space is dry and that is how you should keep your meteorites. Remember that no matter where you live there is moisture in the air. Your meteorites are especially likely to absorb that moisture if they contain chloride (salt) or change temperature. Changes in temperature can cause condensation like that you will find on a cold can of soda. When salt cakes, it is drawing moisture out of the air. If your meteorite has any salt in it it will draw moisture out of the air. Moisture and salt can damage a meteorite very quickly.
To protect your meteorites you should do the following:
- Keep your meteorites dry--that means keep them in dry air.
- Keep your meteorites at a constant temperature.
- Use cleaning and coatings, as appropriate, to protect your specimens.
Keep your Meteorites Dry
Here is a list of things that you can do to keep your meteorites dry:
- Live in a dry place (this is not fool-proof by any means!)
- Don't let your collection change temperature--temperature changes can cause condensation on meteorites
- Never seal your meteorite in a plastic bag
- Keep your collection in desiccated containers. Here is how I keep mine:
|The container is a normal air tight (more or less) container like that you can buy at the supermarket. The desiccant is bagged. It can be recharged by baking in the oven. (Instructions are on the bag). A moisture indicator is taped to the front of the box.|
- Monitor the moisture in the air around your specimens.
- A cabinet with a small light bulb that is on all the time will keep specimens dry in most situations.
- Keeping specimens in the open air of a temperature controlled room better than keeping them in a sealed box without desiccant, a light bulb, or some other means to dry the air.
Use Cleaning and Coating to Protect Your Specimens
In many cases it is not necessary to use heroic measures to protect your specimens. I enjoy keeping some specimens out where I can see and enjoy them. Gibeons, some Canyon Diablos, Sikhote-Alins, and the majority of stones can be left in open air.If you do leave specimens in the open air, you should take some precautions.
Any iron that is left out is likely to be handled--you should assume by sweaty hands. For this reason, you need to clean your specimen periodically. I recommend that you use anhydrous alcohol. As a practical matter it is difficult to get alcohol that contains no water. I use 95% ethyl alcohol from the hardware store. It is about $10 per gallon ($2.50/l) where I live. 99% isopropyl alcohol is usually available from drugstores. Clean the specimen thoroughly.
|Try to avoid putting a meteorite in water that contains salt--that would be softened water. I'm not sure that distilled water is necessary, but properly drying a specimen is important. Soak the specimen in alcohol after using water and heat it to drive out the remaining water.|
The next step is to coat the specimen. There are any number of coatings that can work. You can find a good selection at the hardware store or a gun shop. Among the brands I have used are RustGuardIt, Rig, Rig2, Sheath, and WD40. (I had noted in a prior version of this page that WD40 contained water. I based this on reports I had heard and my observation of an immiscible fluid in a gallon I bought. I am assured that it does not contain water. In any event it provided satisfactory results.)
For etched irons, I heat the specimen to 200º F (95º C) and apply "Rig" grease. After the specimen cools, I wipe off the excess grease.
None of these coatings can be considered permanent. All should be replaced at intervals.
An alternative coating that I have begun using is microcrystalline wax. I soak iron and some stone specimens in microcrystalline wax at a temperature above the boiling point of water for a period of a day or more. The heat drives out moisture and leaves a waterproof finish.
I do not favor hard finishes such as lacquer or acrylic. These can detract from the appearance of specimens. Hard finishes are not permanent as moisture often gets under the coating. Removing and cleaning the finish is much more difficult than for oils. I have seen specimens (mostly stones) where a hard finish was used in place of polishing. This is unnecessary. It takes relatively little effort to take the saw marks off a specimen and put on a proper polish.
If a stony meteorite is susceptible to rust, my policy is to keep it dry. I keep it in a box with desiccant. If any stone is handled much, it is a good idea to clean it with alcohol. I do not use any coating on stones as I believe that coatings interfere with observation of the natural features and sometimes enhance corrosion.
If you collect meteorites, it is inevitable that some specimens will be damaged or deteriorate. Most often the damage can be repaired and further damaged can be stopped or slowed. Damage to most specimens can be related to two things: Rust and chloride (salt). Rust is the symptom, chloride is the disease. Both need to be removed.
Most often rust can be removed with a little elbow grease and a steel wire brush. Use anhydrous (or 95%) alcohol to do your washing. Alternatively, you can use a petroleum distillate rust 'remover'. Sheath or WD40 are examples. On etched surfaces or bare metal surfaces that have lots of cracks, you might want to try phosphoric acid. Naval Jelly is one brand of phosphoric acid rust remover. OSPHO primer is another brand of phosphoric acid. A little OSPHO and a toothbrush can remove a bit of rust from an etched surface without doing significant damage and necessitating re-etching. After you use the acid, be sure to clean it all off using alcohol or distilled water. Etched irons will have to be re-polished and etched.
Troublesome meteorites are often that way because they contain chloride--or more accurately hygroscopic chloride minerals, such as salt--NaCl, that attract water and promote rust and electrolytic reactions in specimens. Removal of chloride is a subject that has been extensively considered by museum curators interested in preserving iron artifacts recovered from marine environments. Look at this page and this one too.
Recently I have been using this method developed by Ray Pickard of Bathurst Observatory in Australia. It seems to work well.
If you have any questions about preserving meteorites, please do not hesitate to drop me an e-mail. If you need desiccant or indicators, I can supply them to you. If you have things that you think should be included here--or deleted, let me know.