What is 'cold bluing' and how does it differ from 'hot bluing'?
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A
Cold bluing uses an oven; hot bluing uses room-temperature chemicals
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B
Cold bluing uses selenium dioxide-based solutions applied at room temperature; hot bluing uses hot caustic salt baths for a more durable finish
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C
Cold bluing is a type of Parkerizing; hot bluing is a polymer coating
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D
They are identical processes applied at different speeds