I got a machine in today, a little one, couldn't pass it up. Major cosmetic issue is it sat too near a concrete pour or something and got spattered a long time ago, and, like most construction machinery, never got cleaned off. It doesn't affect the function but I don't like it and want to remove it. Stuff is tenacious! I want to remove the concrete but leave the paint, decals etc. alone. Any ideas? I've only tried 409 and a rag and the edge of a credit card so far.
GWE
If you're *patient*: get some 9% vinegar and apply using a "pad" of fabric or paper to let it soak in/on. The stuff is mild enough to not bother oil-based enamels but will eat the cement. Reapply/refresh as needed. [You can also use the stuff to clean your coffee maker. ]
If you're *not patient*: try using either a router or a Dremel (with a router attachment) and a flat-ended diamond bit. Adjust the height so that the bit _does not_ extend outside the baseplate. [The objective is to knock off the particles *without* making contact with anything else.]
Once you've knocked off the high points and big chunks, it's time to gather up your patience and apply the 9% vinegar with a "pad".
Muriatic acid. It's what the masons use to clean up mortar. It shouldn't affect the paint, but you might want to do a trial in an inconspicuous spot.
Bob
Acid: CLR (mild) or muriatic (not mild).
Funny how portland cement sticks to stuff and lasts forever where it isn't wanted. But your driveway is just falling apart.
Ever notice how intersections are just full of spilled concrete where the overloaded trucks come to a stop? And they say it doesn't stick to asphalt.
Hey Grant, what about that stuff that eats calcium deposits off your shower head? Oh, BTW, I figured out how to make that grinder spin faster. I just spin it up with a drill motor. And you said it couldn't be done. So there. Eric
OK, I'll bite, what's CLR?
I cannot imagine any paint that can stand up to HCl, either. This is a painted surface with complicated decals which can't come off and aren't easily replaced. Even if the paint could stand up to muriatic, I very much doubt the decals would.
Grant
I routinely de-rust with muriatic/HCl. There is often some paint on the rusty piece and I've not noticed that the acid has affected it. If there has been an effect, it was very minor. But I still suggest a trial.
Well, the acid can be very aggressive with some materials, but totally benign with others. It really does depend. I would not be at all surprised if it did not affect the paint or the decals. But I can't say for sure.
Bob
When I had my floor poured for my shop the guy was super sloppy and splashed concrete all over the side of my metal building. I was angry and he offered to sand it off and repaint it which I know would not have turned out nice. He did say that the concrete companies used "something" to clean off their trucks and didn't think it affected paint but didn't know what it was. I searched the internet and found some similar "something". I called the company and they said it would cost me $80 to ship a gallon because it was considered haz. I told the guy my sob story and he said "hold on a second..." He came back and said quietly that it was just muratic acid and a detergent. He told me to try the acid in a hidden spot. I did and it worked great. I used a plastic bristle brush that the acid melted but it didn't take much brushing. I also hosed it off with water as I went.
Bleach ? HCL ?
It will eat the lime out and maybe frag the stuck on stuff. Maybe some on a paper towel and let it sit over night.
It might mess up the paint. Depending on the paint.
Might cover paint with oil or grease then it should be easier on it.
Martin
Follow your hunch. HCL (Muriatic) will do serious damage.
Harold
A commercial name, Calcium, Lime, Rust. An acidic cleaner, probably at Walmart.
On Wed, 15 Jun 2005 02:57:00 -0500, the opaque "bw" spake:
It's quite similar to LimeAway, which should also work. Then again, a gallon of muriatic acid was only $3.65 from the farm store here, and it works well on stubborn toilet rust stains.
---------------------------------------------- Never attempt to traverse a chasm in two leaps
Smear Vaseline all over the paint and decals, and just dab the acid onto the concrete with a Q-tip. Don't get any Vaseline on the concrete.
Cleaning the Vaseline off, while leaving the paint and decals, is, of course, left as an exercise for the reader. ;-)
Good Luck! Rich
The time for the oil/grease was BEFORE the concrete was poured.
The problem with using HCL for such an application is that it will encourage anything ferrous this in the proximity to rust, even when it never makes intimate contact with the acid. When I refined, I used it by the drum. In spite of the fact that I kept a negative pressure in the lab at almost all times, there wasn't anything ferrous that didn't have surface rusting, even stainless. It is correspondingly hard on aluminum, zinc and other metals. Personally, I wouldn't use it on anything I cherished. It does make a great rust remover, but it doesn't limit itself to oxidized iron. Given enough time, it will completely dissolve steel.
Harold
On Mon, 20 Jun 2005 01:43:46 -0700, the opaque "Harold and Susan Vordos" spake:
Isn't that why it's neutralized after treatment, Harold?
What is your preferred derusting method now?
What do you think of Salt 'n Vinegar water?
-------------------------------------------- -- I'm in touch with my Inner Curmudgeon. --
Yeah, but you can't always neutralize everything that has the potential to be exposed. I think that's my point. I'd recommend using HCL only under very strange circumstances. Removing zinc (galvanizing) might be one of them. One of the things I didn't like very well about HCL is it isn't uncommon for it to single out spots and erode holes. I don't understand why, but I've sure as hell seen it. It does take a long time, but deep rusting would present the perfect opportunity.
Hard to say, for there are always exceptions, but my preferred method tends to be my blast cabinet. If I want rust off something that doesn't lend itself to blasting, and I had to turn to chemicals, I'd next use phosphoric acid. I've used it on steel doors and can't think of a better way to go. It not only removes rust and limits the ability to reform, but prepares surfaces for better adhesion when painting. Auto body guys know it as metal prep..
I've never tried it, but I will probably use that method when I start melting rusted steel scrap for casting. Eliminating rust before melting yields better quality iron (steel is inoculated properly to convert to iron).
Harold
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