Autunite is a metamict mineral, meaning it can disintegrate over time due to radioactive decay and water loss, which weakens its crystal structure. Stabilization with a consolidant can halt this natural disintegration process by infusing the specimen with an acrylic polymer. The two most commonly used consolidants for stabilizing autunite are Paraloid B-72 and Butvar B-76.
Consolidant Comparison
Butvar B-76
Finish: Dries to a matte appearance, offering a subtle, less glossy look suitable for fragile surfaces.
Recommendation: Best for yellow varieties of autunite or meta-autunite that already have a moist appearance. Using Paraloid on these specimens can result in a slimy appearing finish.
Paraloid B-72
Finish: Dries with a slight sheen, providing clearer transparency and a glossier appearance.
Recommendation: Suitable for autunite specimens that do not have a moist appearance.
Important Warnings
Warning for Autunite
Handling or processing autunite may generate radioactive airborne dust particles, which can pose inhalation risks. To minimize exposure:
Avoid creating dust.
Use appropriate personal protective equipment (PPE), such as respiratory protection and dust masks.
Ensure that work areas are well-ventilated and follow established safety protocols.
Warning for Acetone
Flammable: Acetone is highly flammable. Keep away from open flames, sparks, and heat sources. Use it in a well-ventilated area.
Irritant: Acetone can cause irritation to the skin, eyes, and respiratory tract. Wear appropriate PPE, including gloves and goggles.
Toxic Vapors: Inhalation of acetone vapors can cause dizziness, headaches, and nausea. Use it in a fume hood or ensure adequate ventilation.
Avoid Contact: Avoid skin and eye contact. If contact occurs, rinse affected areas thoroughly with water and seek medical attention if necessary.
Preparation
The recommended concentrations of consolidant in solvent are:
10% for Paraloid B-72
5% for Butvar B-76
The recommended solvent is acetone, although ethanol or isopropanol can also be used.
Solution Preparation (100ml)
For Butvar B-76: Dissolve 5 grams of Butvar B-76 in 95 grams of acetone to create a 5% solution.
For Paraloid B-72: Dissolve 10 grams of Paraloid B-72 in 90 grams of acetone to create a 10% solution.
Pre-Stabilization
Before beginning the stabilization procedure, ensure that the specimen is clean and dry. If the autunite specimen has been rinsed with water, allow it to dry for 24 hours before proceeding. Stabilizing moist autunite can adversely affect the final appearance.
Stabilization Process
Prepare the Work Area: Place the specimen in a shallow glass dish or on another surface that won’t be damaged by acetone.
Apply the Consolidant:
Use a dropper or syringe to apply your chosen consolidant solution to the specimen.
Light puffs of canned air can be used to blow away excess solution and prevent pooling.
Move the Specimen:
As the specimen starts to dry, move it to a different area of the glass dish to avoid sitting in the puddle that has formed.
Move the specimen again to a dry area of the glass before allowing it to finish drying.
Second Treatment:
After an hour, apply a second treatment using the same procedure.
If a white residue is apparent on the specimen, it can be removed with acetone.
Final Drying:
Allow the specimen to dry for four hours before mounting or storing.
Additional Notes
Two treatments of the consolidant solution should be sufficient for most autunite specimens. Be cautious with additional treatments, as they may adversely affect the finished appearance of the specimen.