In its pure form, sodium hydroxide is a solid white substance available in flakes or granules or as a half-saturated solution. It readily absorbs carbon dioxide from the air and should be stored in an airtight container. Molten sodium hydroxide is a strong base, but the high temperatures required to create molten form limit its applications. A sodium hydroxide solution will leave a yellow stain on fabric and paper.
Captured with the MT9300 polarizing microscope at 40x magnification using the Infinity 2-1 microscope camera, this image of sodium hydroxide was taken of a powder form of the substance.
Same polarizing microscope setup as above and using the same sodium hydroxide sample, but captured at 400x magnification.