Naval Jelly

[zahc]

Sometimes I want to chemically remove rust. I know there is evapo-rust, but it's expensive. Can I just use phosphoric acid? What concentration?

[RoadKingLarry]

What are you de-rusting?
I've used several methods over the years. Biggest PITA set up was electrolysis but I got damn good results.
I've used the WD-40 brand rust remover soak, worked fine, clean up was a bit messy.
I've also used just plain old white vinegar and it worked about as well as the WD-40 stuff and a damn sight cheaper.

[Regolith]

Project Farm did a test of some common rust removers.

https://www.youtube.com/watch?v=6-MC_ZEXQbw

TL;DW:

Best out of the tested products seems to be Muriatic Acid, Krud Kutter, Evapo Rust, Naval Jelly, and white vinegar, in that order.

Muriatic acid seems to work well if the item is durable, but it can cause etching, eats away non-metal bits, and doesn't protect item long term. Naval Jelly seems to be the choice for when you need something that won't flow. CLR & Coca-Cola were deemed useless or not worth bothering with.


 He didn't test phosphoric acid (except for the small amount in Coca Cola).

[zahc]

In my experience muriatic acid CAUSES rust, I don't doubt it probably removes rust too...on the other hand, I thought some acids would leave a mild oxide protection layer kind of like mill pickling.

Right now I need to de-rust a bearing bore. I'd rather remove the rust chemically before trying sandpaper or anything like that. I will try vinegar.

[Nick1911]

I really like Evapo-rust.  It is expensive, but man, it does a nice job.

[Regolith]

In my experience muriatic acid CAUSES rust, I don't doubt it probably removes rust too...on the other hand, I thought some acids would leave a mild oxide protection layer kind of like mill pickling.

It completely strips the part down to fresh, bare metal, without any protective oxide layers. That's probably why it seems to cause rust.  I think he mentioned you need to paint/blue or whatever the part almost immediately after using it.

[Jim147]

It completely strips the part down to fresh, bare metal, without any protective oxide layers. That's probably why it seems to cause rust.  I think he mentioned you need to paint/blue or whatever the part almost immediately after using it.

Yes that's what it does. We had a tank of it in the machine shop. Dunk clean but rusty part in tank and let it bubble away. Rinse with hot high pressure water then dunk in tank of rust inhibitor.

[fifth_column]

I haven't tried it, and more setup is necessary, but I've heard good things about electrolysis. I'm debating setting something up like this guy has:

https://www.youtube.com/watch?v=V-prcdrvb_E

[zahc]

An overnight bath in a Ziploc bag of vinegar worked really well, rust is all disappeared and leaving a thin film of black smut.