Here is what to do about rust

grhanka · 03-31-2022, 07:10 PM

If you ever worked in an outdoor steel industry, you might have known this as "Ospho." It's phosphoric acid, and it converts rust into a hard black crust. Just spray it on the rusty bits every week or three. It works, and you can get it at Home Depot.

zero_dgz · 03-31-2022, 07:22 PM

I use the same stuff (albeit in a big jug from Tractor Supply specifically labeled as "rust prep").

This is only step 1 of the solution. It will indeed convert rust to a paintable surface. The key word being paintable. You will never win the battle against rust unless you paint the surface after application of this stuff since the final product it creates is not sealed against further moisture intrusion. This is the very important step 2. I use either VHT epoxy paint or just regular old Rust-Oleum, depending on the item.

Once you properly paint the surface after application you should not have to do it every week or three, you should not have to do it ever again.

ChillRider · 04-04-2022, 10:58 AM

Yup, I know about this stuff, also sold as "rust converter", often containing tannic acid as well. It works very well for certain kinds of rust, it even turns certain types of steel black immediately even when there's no visible rust (esp. if applied immediately after grinding/wire brushing, with others not as much, esp. thin, rusted sheets.

I second the need to paint treated stuff as soon as possible. Also, and that's a big weakness, don't be tempted to use it on parts that get hot, e.g. exhaust pipes. It may appear to work vey well and turn into a thick, black coating with no effort, but ferro-organic compounds it creates will simply flake off at even moderate amounts of heat.

03-31-2022, 07:22 PM	#2
zero_dgz Join Date: Jan 2020 Posts: 252	I use the same stuff (albeit in a big jug from Tractor Supply specifically labeled as "rust prep"). This is only step 1 of the solution. It will indeed convert rust to a paintable surface. The key word being paintable. You will never win the battle against rust unless you paint the surface after application of this stuff since the final product it creates is not sealed against further moisture intrusion. This is the very important step 2. I use either VHT epoxy paint or just regular old Rust-Oleum, depending on the item. Once you properly paint the surface after application you should not have to do it every week or three, you should not have to do it ever again.
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04-04-2022, 10:58 AM	#3
ChillRider Join Date: Jun 2020 Location: A small country with a funny name Posts: 164	Yup, I know about this stuff, also sold as "rust converter", often containing tannic acid as well. It works very well for certain kinds of rust, it even turns certain types of steel black immediately even when there's no visible rust (esp. if applied immediately after grinding/wire brushing, with others not as much, esp. thin, rusted sheets. I second the need to paint treated stuff as soon as possible. Also, and that's a big weakness, don't be tempted to use it on parts that get hot, e.g. exhaust pipes. It may appear to work vey well and turn into a thick, black coating with no effort, but ferro-organic compounds it creates will simply flake off at even moderate amounts of heat.
	0