Spray on rust

[ptk]

In the basement ceiling of our 100-year-old house, there are steel beams where the plaster has come off. I have knocked off the plaster, and you can see that the beam has corrosion, which explains why the plaster is coming off along the beam.
1) Is there a substance to spray directly on the beam that protects without having to sand off the rust before replastering?
2) If not, what should I sand with to complete the task as quickly as possible?

 

[swirve]

Depends a bit on... But it's probably good to remove the rust, a rotating steel brush is usually good for removing most of it and then finish with some rust eater. Then rust protection primer and finishing paint.

 

[ptk]

Depends a bit... But it's probably good to remove the rust, a rotating wire brush is usually good to remove most of it and then finish with some rust converter. Then rust protection primer and finish paint.

What is a rust converter?

 

[swirve]

What is a rust eater?

https://www.biltema.se/bilvard/bilunderhall/rostskyddsmedel/rostatare-235-ml-2000017147

 

[ricebridge]

What is rostätare?

A scam product that is barely available for purchase anymore.

 

[[old rusty]]

A scam product that is hardly available anymore.

Unclear what you're buying but not my experience..

Phosphoric acid works great on rust.
Or if you want to pay a lot for the acid, you buy Carosol Rust Eater or similar.

 

[ricebridge]

1) Is there a substance to spray directly on the beam that protects without needing to sand off the rust before I repaint?
2) If not, what should I sand with to complete the task quickly?

1) No.
2) Flap disc (google it) that you attach to an angle grinder is best in my experience. Expect one of these per 1-2 meters depending. A rotating steel brush that you attach to a drill also works but takes much longer, and is usually best for deep cleaning where the flap disc can't reach.

 

[ricebridge]

Unclear what you are buying but not my experience..

Phosphoric acid works great on rust.
Or if you want to pay a lot for the acid, you can buy Carosol Rostätare or similar.

When I have used rust removers — and quite a lot of it over a couple of years — the rust has happily gobbled it up and continued rusting. So I don't care much for it.

 

[AndersS]

When I've used rust eater — and quite a lot of it over a couple of years — the rust has happily chewed through it and continued to rust. So I don't think much of it.

But surely you primed and lacquered after? I use Hammerite's products, they last a long time.

 

[[old rusty]]

When I've used rust eater — and quite a lot of it over a couple of years — the rust has happily eaten it up and continued to rust. So I don't think much of it.

Interesting.
My experience is the opposite. Usually provides a pretty good base for further surface treatment.

Then again, I mostly use it where blasting isn't possible (or I'm too lazy), so in places that later get undercoating treatment, which stops most rust on its own.

 

[ptk]

1) No.
2) Flapdisc (google it) which you attach to an angle grinder is the best according to my experience. Expect to use one per 1-2 meters depending on the circumstances. A rotating wire brush that you attach to a drill also works but takes much longer and is usually best suited for deep cleaning where the flapdisc can't reach.

Thanks!

 

[Lostmoose]

I have very good experiences with Isotrol.

 

[ricebridge]

But you have primed and lacquered afterwards?

Of course.

 

[AndersS]

Of course.

Switch to Hammerit and it doesn't have to be Hammarlacken. But if it's on cars, it might be different, nothing seems to work really well there.