One of the often-touted uses of WD-40 is that it "dissolves rust". The official website states that WD-40 "breaks down the bonds between metal and rust".

I can't understand how this would work, since there seem to be no rust-dissolving ingredients in WD-40 and it seems the product is more basic than acidic.

A (possibly not exhaustive) list of ingredients:

I can imagine that the low viscosity of WD-40 allows it to get in all nooks, making it easier to grind rust particles away because it acts as a short-term lubricant. Is that actually how it works, or am I missing something?


1 Answer 1


I'd say it works by coming out as a liquid. Then it diffuses through the porous rust layer or travels along the steel edge and expands to gas- as the mixture has a highly suppressed vaporisation point to push the rust from the inside. Steel has a high surface affinity for hydrocarbons as demonstrated by high difficult it is to clean. Partial vaporisation is plenty powerful enough to knock off rust.


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