Rust - Rusty Screws and Nails in x100 Magnification

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Color is perceptual and there is no such substance in nature which can be defined by unified single color value. Color should be always considered as a range and every color and luminance which falls into that range should be considered valid. If we take a look on these rusty screws and nails, we can see how rich the color is and how it differs even withing the same sample.

Rust is basicaly a hydrated iron, also known as iron oxide - reddish-brown oxide formed when iron reacts with oxygen and water - this reaction is known as oxidizing or in very plain words, a corrosion. Whats interesting is that to recover metal from ore, we smelt it. The smelting process that converts iron ore into iron metal is the chemical opposite of rusting. So, while we think of rust as coming from the rusting of iron, in reality iron comes from the un-rusting of rust.

These are screws and nails I pulled out of the broken fence 2 years ago and left outdoor so I can measure and analize how they age and corrode over time. Usually screws and nails are made of hardened steel (an alloy of iron and carbon containing less than 2% carbon and 1% manganese and small amounts of silicon, phosphorus, sulphur and oxygen). They are often dipped or coated to prevent corrosion in harsh conditions or to improve adhesion. Since thesa are nails and screws pulled out of wood, their coating was surely damaged which exposed them for further corrosion. Ordinary nails for wood are usually made of a soft, low-carbon or "mild" steel (about 0.1% carbon).

While rust is technicaly a metal, it lost it smetal properties during oxidisation and can be considered as a dielectric material, therefore its average color is pretty reliable to measure. The average albedo value of this exact sample, measured in 0-255 PBR range and sRGB was R83, G68, B57 with relative luminance level at 0.276.

Please always consider this value as an aproximation and take it with a grain of salt, as color in nature is never 100% uniform, and should be always considered rather as a palette of color values within a certain color range.

To preview more PBR albedo values, please watch my PBR Color Reference List video:    • PBR Color Reference List for Material...  
or maybe even consider it's paid version including my PBR Color Calibration Guide: https://gbaran.gumroad.com/l/rjthlk

Big thanks to everyone who purchased it already as it really helps in my further research

Hope you enjoyed the video and till the next one!