Phosphoric acid for rust on chrome parts

[jetmechmarty]

I have some very nasty looking chrome fenders, so I decided to do some experimenting.

This is a junkyard fender off of an XS1100 Special. It's the sacrificial lamb.

Rusty enough?

I put about 5 gallons of water into the bucket. Then I added 2 cups of phosphoric acid. Do it that way to reduce risk of splashing acid. Then, I added the chrome fender. It is a weak solution, so that I could maintain control. That fender remained in solution for 24 hours thereabouts.

Straight from the bucket. No scrubbing, just a hose rinse.

The rust has been removed. Here it after a quick once over with chrome cleaner and Meguiar's Quick Wax.
The acid did not appear to damage the chrome. It cleaned up well without any significant work. I'm going to leave it out on the porch for a while and see how it holds up. As bad as it is pitted, I'll be throwing it away.

This XS650 fender just went into the bucket. I hope it's usable after it's done cooking.

 

[jetmechmarty]

Fender bottom. It got most of it. All I had to do was leave it longer. The moisture is WD40. It flash rusts.

 

[Grimly]

It's good stuff.

 

[FLEA]

if you look at most rust convertors they are a percentage p/acid often 8-12 percent only at a large price for a small bottle . buy it direct from chemical co .. pool maintaince co etc its 80 percent pure at a lot cheaper price .. ie small bottle rust convertor here is 17 bucks .. 4 lts at 80% 70 bucks .. has to be no more than 80% or its a solid .. dilute with water when using , the less dilution the faster it works ... great stuff BUT using strong can cause paint discolouration in streaks with your surrounding paint work .. DONT use a cheap brush if brushing it on , the brissles will fall out and stick to what your working on ,use a good quality brush , it will wash off .. prices and location are in aust will be different elsewhere (hows that for a disclaimer)

 

[jetmechmarty]

I have what is left of a gallon of acid. It was very cheap. I’ve had it a long time.
I’m at about 5% solution, so it’s slow. I’ve derusted fuel tanks with it. Works great. I did this to see if chrome would stand up to it.

 

[Jim]

I use muriatic acid from Ace Hardware for about 15 bucks a gallon. Muriatic acid is actually hydrocloric acid. Not sure why the name change but... whatever. It's a 28% solution. Fill a rusty tank with it and it's clean as a whistle an hour later. But... it's nasty stuff. A respirator and face shield are mandatory. Is the stuff you're using as nasty as that Marty? If not I might give it a go.

 

[WideAWAKE]

Jim - this is what you want - pretty much no fumes. I have to use it in small closed off rooms all the time. No issues.

I use it all the time to clean rust - a diluted version works great in the ultra sonic as well.

off topic but if anyone is using an ultra sonic and isn’t bagging their parts, your missing out haha. No need for filthy water and you use less cleaning solution.

 

[FLEA]

was good to see the effect on chrome , have never been game , have a couple of guards than may now be done shortly

 

[Tomterrific]

Phosphoric acid is what gives cola its sharp taste. It also leaves iron phosphate over the surface so the part doesn't rust as fast as it does with HCL. It is used to Parkerise gun parts. Phosphoric is the best!

Where can we get it?

Tt

 

[ThatXS650Guy]

I use MSR (Milk Stone Remover) with water in a 5 gallon bucket. Works great and mild enough to get on your hands w/out freakin out.

 

[nj1639]

I'll reiterate,
Always add the acid to the water.
For memories sake I use A to W, A+W, A+W Rootbeer.....Yummm, good.
Never W to A, W+A, Waaaah! Bad.
lol

 

[cra-z1]

My next door neighbor uses a bathroom cleaner called the works for small chrome stuff and works great. You can buy it as a liquid in the dollar stores for a buck if you only need a small amount. Not sure what the chemical is in it but I was amazed with the results. Soak it for an few hours or less and rinse well. Rust melts away. Put it back in the bottle for future use.

 

[jetmechmarty]

I use muriatic acid from Ace Hardware for about 15 bucks a gallon. Muriatic acid is actually hydrocloric acid. Not sure why the name change but... whatever. It's a 28% solution. Fill a rusty tank with it and it's clean as a whistle an hour later. But... it's nasty stuff. A respirator and face shield are mandatory. Is the stuff you're using as nasty as that Marty? If not I might give it a go.

I respect it as if it is that dangerous, however, I don't detect fumes when I open it. In a rusty XS650 Special tank, 2 cups diluted in water will destroy the rust overnight. Right now, I have that 650 fender in solution since yesterday afternoon. Two cups of the above are is diluted into at least 5 gallons of water. I have control this way.

For those reading this that may have a question, acid will eat steel. If your solution is strong, you can destroy a fuel tank or other parts quickly. For light rust, I recommend Metal Rescue, Evoporust, or something similar. My experiment involves heavily rusted parts with chrome plating. I really wanted to see if chrome would tolerate it.

Yes, I've used muriatic acid as well. I prefer this one, but I don't remember why exactly. Both do the job. Both need to be respected.

 

[jetmechmarty]

Where can we get it?

Tt

Hardware store. I expect Lowe's and Home Depot have it.

 

[Jim]

This guy is right proud of his stuff...

 

[jetmechmarty]

This guy is right proud of his stuff...

View attachment 174915

@Tomterrific could have easily been the one who guided me to this stuff in the first place. We've been communicating on the Micapeak XS650 email list for about 20 years!

I'm sure $8-$12 per gallon is the price of this stuff. Metal Rescue is a little over $20 per gallon. That's my choice if they're the same price point.

 

[jetmechmarty]

This must be the new label. $14-$20. Read the label and make sure it's still phosphoric acid before you buy it.

 

[jetmechmarty]

85% at Walmart for $45. That's enough to last an extremely long time. It's food grade phosphoric acid.

 

[Jim]

Well, ya talked me into it Marty. I'm never in a hurry when de-rust parts and I dislike having to "suit up" every time I use my hydrocloric tank... so I'm gonna give the phosphoric a try.

 

[jetmechmarty]

Well, ya talked me into it Marty. I'm never in a hurry when de-rust parts and I dislike having to "suit up" every time I use my hydrocloric tank... so I'm gonna give the phosphoric a try.

I just checked my 650 fender. It's over 20 hours and still cooking. My concentration is very low. Full strength, my guess is the Prep & Etch would had wrecked it by now. I have a lot of irons in the fire, and with the low strength solution, an hour or three isn't going to make much difference. Plus with this stuff you can put it in a big tub for large parts. My bucket would cost about $150 to fill with Metal Rescue. Bear in mind they are not the same thing.