Thread: Bondall Ranex Rustbuster

It works very well to clean it up before doing some form of protective finish. The surface will rust again if you don’t protect it

The active ingredient in Ranex is Phosphoric acid (PA) and Ranex only contains between 10 and 30% PA.

Ranex costs $30/L but for $22 at Bunnings you can also purchase a litre of Chemtech rust converter that contains between 30 and 60% PA

I personally don't like either all that much as they also contain too much detergent (OK that does help wet the surface) that unfortunately also produces a residue when it dries - OK it can be washed off but then the steel starts rusting again.

In your application a detergent residue might not matter that much but if you want a really smooth finish then for $28/L I use the 85% PA (for food grade hydroponic use) from ebay see Phosphoric Acid 1L Food Grade Hydroponics,swimming Pool, Rust Removal | eBay This has no detergent in it but if needed you can always transfer some to a temporary container and add a couple of drops of dishwashing liquid. Just watch out, as 85% is pretty strong and will make a mess of any terrazzo etc. Also don't wash it off - let it dry and paint straight over the top.

thanks guys very helpful advice, looks like the Ranex as she has that already...lazy SIL bought it but got no further.

Originally Posted by Tonyz

thanks guys very helpful advice, looks like the Ranex as she has that already...lazy SIL bought it but got no further.

Luckily she has a self starting dynamo of a B-I-L to rely on then.

Make sure you chip or scrape of off any scale; PA loves a light coating of rust but can’t work its magic through layers of it. My preferred method is to hit it with a carbide scraper and some elbow grease.