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topic 14857

Remove blue discoloration from motorcycle exhaust?


Q. The chrome plating on motorcycle exhaust systems discolors to a dark blue in almost all cases. This is assumed to be due to the heat effects and oxidation. It has been expressed in some circles that the bluing is due mainly to the copper underplate and should be eliminated if the copper was not used and the nickel was applied directly to the steel. What do the experts think?

Bob Denney
avionics - Tampa, Florida

September 4, 2009

Q. Dear all,

We have a motor bike modifying unit. Most of our customers object to silencer and exhaust pipe bluing (those were Ni/Cr plated). After running over a 1000 km, plated silencer colour changed to dark blue.
We want to know how to avoid it. Is there any specific process design for above-said parts while plating. Please help us.

M. Ravi shanker
product designer - Chennai, Tamilnadu, India


Q. I would like to remove some of the bluing that has occurred on my motorcycle's single wall exhaust tubing near the engine heads. Is there a product that will remove the bluing? Chrome polish doesn't seem to touch it.

Michael Hunt
- Virginia Beach, Virginia


A. Learn to love the blue look. Yes there are many commercial products like "Blue Job" [linked by editor to product info at Amazon], "Blue Buster" [linked by editor to product info at Amazon], "Blue Away" [linked by editor to product info at Amazon], and more which claim to remove it--but repeatedly abrading a surface with any product will destroy the chrome luster.

If anyone wants to advertise their product here or anywhere, they're welcome to. And if anyone has GENERIC suggestions we'll be happy to have them, but please recognize that this kind of thread catches the eye of every product salesperson, and we're soon buried in spam that readers don't want to read, and we don't want to edit and post ... and then when we won't post the spam, they pretend to be satisfied customers and post glowing reviews, and there's no way for us to tell honest testimonials from fictitious plants :-)

Sorry but this website is essentially anonymous and it's just not the place for product testimonials. Apologies.

Ted Mooney, Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey


A. To simulate this process you can use a battery charger [linked by editor to product info at Amazon] , a piece of copper tubing, some fiberglass cloth to cover the tubing, and some watered down Muriatic Acid [linked by editor to product info at Amazon] about 2 parts water to 1 part acid. Wrap the fiberglass around the tubing. Hook up the negative clamp to the tubing and the positive to the muffler. Turn on the battery charger to start mode, about 60 amps at 12 volts setting, and then dip the fiberglass into the acid and rub the area to be cleaned. The blue magically disappears. IMPORTANT: wipe off with water and wash right away. Try this on a scrap piece if you can first.

John Button
- Springfield, Michigan


Q. I am a motorcycle owner whose chrome exhaust is bluing terribly. I'm interested in learning more about the answer typed by John B ofSpringfield, Michigan. It seems incomplete and, since it appears that the procedure could be dangerous - with battery charger and acid and all - I was wondering if all the facts are disclosed and how often the process must be repeated, if at all.

Jim M [last name deleted for privacy by Editor]
motorcycle enthusiast - Pollard, Arkansas


A. Yes, it's dangerous to use muriatic acid if you're not trained in its use. Further, it can destroy the chrome plating, leaving only the underlying nickel plating. If you want a second opinion, I don't think it's a good idea.

Ted Mooney,
Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey


RFQ: What about finding perhaps a metal shop or some other business that may do the procedure for a fee?


Jim M [returning]
- Pollard, Arkansas
^- Sorry, this RFQ is outdated
     View Current RFQs


A. Muriatic acid will not destroy chrome in watered down concentrations. In fact, I use it all the time to remove scuffed cylinders in engines where aluminum has transferred from pistons to cylinder walls to remove the aluminum and leave the chrome liner unharmed. It works very well and I have never seen, or heard, about Muriatic acid eating chrome. That said, I would think that using it to remove bluing on the pipes as he suggested would be worth a shot. It sounds feasible what with the current flow and the acid reacting with the current. I will be trying it on some old blue pipes I have to see if it works. Stay tuned.

Steve Swatson
- Winn, Maine, USA


A. Hi Steve. Thanks. Muriatic acid is exactly the material that plating shops use for quickly stripping chrome, without electricity. If you have the time for one of's longest and most rambling threads, but one of our most informative and entertaining, see letter 12044 How to make hydrochloric (muriatic) acid :-)

Yes, if something is diluted, it won't do as much as it did as fast as it did when not diluted; but if I wanted to avoid stripping the chrome, I don't think I would pick the material known for stripping it best.

Ted Mooney,
Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

November 13, 2008

A. Here's the key to cleaning STAINLESS STEEL exhaust headers with bad bluing NOT CHROME. It has certainly worked for me. Mix 2 parts water to 1 part Muriatic Acid. Paint this solution on header with cheap paint brush. (Caution! Muriatic Acid is a form of Hydrochloric Acid and can burn skin. (Please be responsible here and wear rubber protective gloves [linked by editor to product info at Amazon] and goggles [linked by editor to product info at Amazon].) This mixture will remove yellowing and other crap on SS exhaust but not bluing. Leave on for about 10 minutes. Afterwards, wash thoroughly in soapy water, hose off and let dry. Then get a can of "Blue Job" [linked by editor to product info at Amazon], and USING APPLICATOR CLOTH included (Some sort of catalytic reaction here.)put a thick coat of Blue Job goo on all areas you want to look better. Leave this stuff on to dry for at least 12 hours! Afterwards, get an SOS Pad and attack the header. With some elbow grease and effort you can get the stainless steel exhaust header looking like new again! To keep the pipes from bluing again get some VHT high temperature silver spray ceramic coating and spray the INSIDE of your exhaust headers after you have cleaned them out with Gunk or carb cleaner. WARNING! Again, do not do this procedure with CHROME PIPES as the Muriatic Acid and SOS Pads will strip the chrome off the exhaust headers.

Jesse Stuart
- Daytona Beach, Florida

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