It was used in two instances to remove rust from 1) balcony tiles and 2) hand tools (pliers, screwdriver, etc.). I applied it with a brush, let it sit for 15 minutes, and rinsed with water.

In both cases, it failed to effectively remove the rust and required a lot of scrubbing, both with a wire brush for the tiles and with the rough side of a dishwashing sponge for the tools.

Especially on the tools, it left a blackness/dullness on their surface that did not go away no matter how much I rubbed them. Even a polishing cream failed to remove it, so I believe it damages their metal and it is best not to use it on them.

The product's claim that it eliminates the need for scrubbing is inaccurate. In general, it is inferior to the circumstances and I do not recommend it. I had better and more economical results in rust removal with a hydrochloric acid-based product like kezapi.