Evaporust Warning

[mr_houston]

I want to pass along a mistake I made using Evaporust this week, so you don’t do the same.

I recently bought this beautiful Craftsman razor. I does have black rust on the toe.

Following my usual practice, Step 1 is to remove any active rust. I typically use Evaporust to make sure to get into deep pits, etc. However, I didn’t want to soak the whole blade (esp. the spine) and then have to polish any remaining black residue from the ER. So, I just soaked the toe with the blade leaning at an angle. I left it in for 36 hours.

It turns out that the website says to fully emerge your rusted item in ER, but doesn’t say why. Here’s why. ER will create an etched line at the point of ER and the air. You can see the line and where it ate away the bevel edge.

I’ve confirmed the problem elsewhere - LINK

 

[alex1921]

Yes, I had the same thing happen to the tang of a razor years ago when I tried Evaporust.

 

[Frank Shaves]

Sorry to hear/see! Did the Evaporust remove enough steel that you can feel the line between the two sections with your finger?

 

[mr_houston]

Not with finger, but slightly with fingernail.

 

[Frank Shaves]

^
I now understand how this stuff removes rust and pitting. I will stick with my wet/dry sandpaper.

 

[Gamma]

Works via selective chelation. Obviously, different metals can/will behave differently.
The 'water line' issue is a known thing. Seems like the 'line' area goes through repeated instances of oxidation, and oxidation removal and so on. The instructions are clear, they tell the user to immerse the item. .
I can't imagine needing to treat a blade for 36 hours with checks every 30-40 minutes. longest I've ever gone is maybe 3 hours.
There is a video where someone left old tools soaking in ER for 8 years. They didn't dissolve.
Doing 'spot work' with rust removers is always sketchy.

 

[Legion]

Well...

Looks like a good candidate for a shorty.

 

[duke762]

Whoa... good info to keep in mind!

 

[Frank Shaves]

Thanks for the explanation, Keith (@Gamma). I have always wondered how these types of products work.

Do metal polishes like Mothers also work in this way or are they just abrasives in paste?

It seems as if the polishes will continue to remove metal indefinitely if you don't use your eyes, say "Enough!" and stop.

 

[Gamma]

I don't use Mothers. Usually use Simichrome or Wenol.
Neither of those two are chemical-action rust removers.

A lot of rust removers are acid type - like CLR. I think Naval Jelly is too.
NJ has a time limit of something like 15 minutes. I have had blades in CLR for much longer. Typically, these products are used by with frequent inspection to see when 'done', and then the item and the bath gets neutralized. It's not supposed to be 'set it and forget it' until whenever.

Evaporust isn't an acid but still needs to be monitored. I don't know if any of those products are all that 'good' for spot work on showy items tbh. Once a spot or a line or a mark is 'burned in', getting rid of it is really difficult.

 

[Frank Shaves]

^
Thanks, Keith (@Gamma)!

 

[Legion]

Thanks for the explanation, Keith (@Gamma). I have always wondered how these types of products work.

Do metal polishes like Mothers also work in this way or are they just abrasives in paste?

It seems as if the polishes will continue to remove metal indefinitely if you don't use your eyes, say "Enough!" and stop.

They are an abrasive in a paste. Having said that, the pastes are not always PH neutral, so you don't want to leave it on the steel for an extended time. The abrasive might be something as simple as finely ground pumice, which is hard enough to remove surface tarnish and oxidisation, but is not going to remove much actual steel in a hurry.

Most rust removers are generally not removing rust. They are converting it with an acid, like phosphoric or tannic acid, turning the active iron oxide into more neutral iron phosphate.

Because these solutions are acidic, that's why you get the "water line", where the acid is reacting with the water in the atmosphere where the two meet.


I remember when I worked in a lab years ago, and there were drums of heavy organic solvents in use. Once the drums were partially used you had to pump out the air, or introduce another gas, so that an acid layer would not form on the surface of the solvent and eat the drum. Same principle, I guess.

 

[eKretz]

Not sure if any of you are familiar with "gage blocks." These are highly lapped, extremely flat (within millionths of an inch - .000006" on average) dimensional blocks of hardened high carbon steel used in machine shops. I did a test with one of my old ones by submerging it in EvapoRust for several consecutive days, pulling it out and measuring it with a micrometer every 24 hours. The micrometer I used resolves to .00005" and showed zero dimensional change throughout the full test. So I guess the lesson here is: RTFM. Don't partially submerge your parts, and you'll likely be fine.

EvapoRust is *very* slightly acidic as I understand it, but only just so. Its pH is somewhere around 6 if I recall correctly.

 

[Gamma]

Evaporust is not acidic. It's ph neutral.

It removes rust by converting the iron in the iron oxide 'rust' into solution and a second reaction that converts that new solution into iron sulfate.

It can remove iron from iron oxide, but can't remove iron from steel.

It's important to understand the difference between how ER works vs acid based rust removers. It can make a difference in choosing a product for a specific task. Also helps to understand what is going on when stuff like what the OP went though happens.

ER non acidic and non alkali.
The 'water line' in the OPs blade was not caused by acidic or alkaline action. Likely due to the level receding due to evaporation or exhaustion and repeated cycles of oxidation, chelation, etc.

Mothers is PH neutral I think. Simichrome is alkaline. Not sure about Wenol. Online rumors claim that some metal polish pastes contains oxalic acid (rust remover) but I've never seen it listed on any msds/sds sheets.

 

[mcee_sharp]

Argh, sorry to see/hear that.

It seems like something that would be completely out of my playbook if I delve into restos :\

 

[Darth Scandalous]

Online rumors claim that some metal polish pastes contains oxalic acid (rust remover) but I've never seen it listed on any msds/sds sheets.

I think Brasso has oxalic acid. Not a paste though and I've never used it on steel. BKF uses oxalic acid but that's not really what I'd call a polish.

Edit: yes, Brasso does. BRASSO® Metal Polish - https://rbnainfo.com/product.php?productLineId=189

 

[Tanuki]

I have a lot of native oxalis growing in the yard. Perhaps I can do green-certified rust removal with the leaves.

In addition to oxalic acid, I suspect Brasso has some very fine abrasive in suspension, just based on the deposits in the threads of the extremely old can i have.

 

[Gamma]

@Darth Scandalous
I was actually targeting pastes specifically because the rumor usually pops up in forums discussing Mothers paste.
Yeah, it's in a lot of other products. In potatoes too, a common old-school fix for rust on cast iron.

 

[Darth Scandalous]

I have a lot of native oxalis growing in the yard. Perhaps I can do green-certified rust removal with the leaves.

In addition to oxalic acid, I suspect Brasso has some very fine abrasive in suspension, just based on the deposits in the threads of the extremely old can i have.

Pumice is listed on the SDS. We had a bunch of sorrel this year, made a nice tangy pesto.

@Darth Scandalous
I was actually targeting pastes specifically because the rumor usually pops up in forums discussing Mothers paste.
Yeah, it's in a lot of other products. In potatoes too, a common old-school fix for rust on cast iron.

Gotcha. I was just thinking through the products I have in my house.

 

[johnmrson]

I knew that there was a reason I use a buffer and greaseless compound.