Author Topic: Surface rust on exhaust pipes  (Read 639 times)

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Offline joolsuk

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Surface rust on exhaust pipes
« on: July 12, 2019, 12:18:54 PM »
I have some exhaust pipes that work fine and are robust but
have some surface rust on underside (as per pic).
Now I can cure that rust (phosphiric acid .......) but
what can I paint over it with ? (to protect )

I am not 're chroming them.

The area is not really visible but I think it needs to be attempted to be silver.

Any hand paint silver or chrome paint anyone recommends?

[ for info tis a rd250d 1977 and I am going for the 3 year old restore look]
1977 RD250D (mechanical restore)
1980 GS550E
1982 GPZ750R1 (Restore)
1980 GSX250E (mechanical restore)
2002 Stihl FS55 Strimmer (mechanical restore)

Offline striker1423

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Re: Surface rust on exhaust pipes
« Reply #1 on: July 12, 2019, 12:54:36 PM »
Polish as much of it off with chrome polish and 0000 steel wool. You will be surprised how much of it cleans off. To protect you can put a bit if oil on it, or even nail polish. 

But if determined to paint it I am not sure what paint to recommend.  I can just say how much my pipes cleaned up when I thought they were destroyed.
« Last Edit: July 12, 2019, 12:56:17 PM by striker1423 »

Offline joolsuk

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Re: Surface rust on exhaust pipes
« Reply #2 on: July 12, 2019, 01:26:33 PM »
Good plan but I think I have exhausted all abrasive methods
to make them better.
The rust is now solid and exhausts as good as i can get.
I agree with your method mind.

steel wool , metal polish etc for rest of them but this bit
needs covering now.

I'll look for chrome paint as it won't be seen .
Perhaps even a masked off section of hammerite .
1977 RD250D (mechanical restore)
1980 GS550E
1982 GPZ750R1 (Restore)
1980 GSX250E (mechanical restore)
2002 Stihl FS55 Strimmer (mechanical restore)

Offline Astute Greaser

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Re: Surface rust on exhaust pipes
« Reply #3 on: July 12, 2019, 01:38:59 PM »
Zinc Galvanising Spray Paint Silver 400ml
https://www.screwfix.com/p/no-nonsense-zinc-galvanising-spray-paint-silver-400ml/40801?_requestid=355669
The zinc is sacrificial to the steel and helps to stop the rust.

    Touch-Dry in 20-30 Minutes
    Good Filling Properties
    High Adhesion
    Petrol & Chemical-Resistant
    Weather-Resistant

Plus its cheap

Offline joolsuk

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Re: Surface rust on exhaust pipes
« Reply #4 on: July 12, 2019, 01:49:22 PM »
I like ! a lot

What prep you reckon? rub down a maskable rectangle
of rust and chrome. prime then use the galvanizing spray ?

what primer for sanded chrome ?

I tell you what would we or more like it I do without this site ?
1977 RD250D (mechanical restore)
1980 GS550E
1982 GPZ750R1 (Restore)
1980 GSX250E (mechanical restore)
2002 Stihl FS55 Strimmer (mechanical restore)

Offline Astute Greaser

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Re: Surface rust on exhaust pipes
« Reply #5 on: July 12, 2019, 08:17:17 PM »
If you've already removed as much rust and loose chrome and treated surface plus cleaned, then you don't need primer. It is primer, depended upon what you may which to top coat with. Personally I would just use the zinc spray if its on hidden underside. See how it lasts and if you're happy with colour. Its not chrome and will need doing again but it will preserve.

Offline joolsuk

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Re: Surface rust on exhaust pipes
« Reply #6 on: July 12, 2019, 08:29:45 PM »
Colour will be fine the question is will spray stick on
chrome?
I will mask a  rectangle and some of it will be Chrome and I will spray in that rectangle.

I understand it will be fine untreated rust but there will be a small sections of Chrome
« Last Edit: July 12, 2019, 08:32:31 PM by joolsuk »
1977 RD250D (mechanical restore)
1980 GS550E
1982 GPZ750R1 (Restore)
1980 GSX250E (mechanical restore)
2002 Stihl FS55 Strimmer (mechanical restore)

Offline striker1423

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Re: Surface rust on exhaust pipes
« Reply #7 on: July 13, 2019, 03:48:04 AM »
I would think it will stick to the chrome OK. Paint needs a mildly rough surface generally for good adhesion, but it shouldn't require a ton of  work to allow it to cover over dulled chrome, especially since cleaned rusty metal is generally rough enough. If it comes off parts of the chrome itself that won't matter as long as the exposed metal is covered up. Reapply once a year if needed and you should be good to go.

Offline joolsuk

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Re: Surface rust on exhaust pipes
« Reply #8 on: July 13, 2019, 07:20:31 AM »
Yes you are right .
I should and probably will get them 're chromed at some point
but alas now need to make it functional and preserved.
People would have to lay on the floor to see the fix......

After all its summer and this bike needs to be ridden .
Will post result.
1977 RD250D (mechanical restore)
1980 GS550E
1982 GPZ750R1 (Restore)
1980 GSX250E (mechanical restore)
2002 Stihl FS55 Strimmer (mechanical restore)

Offline joolsuk

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Re: Surface rust on exhaust pipes
« Reply #9 on: July 13, 2019, 04:41:06 PM »
I bought that zinc spray paint from screwfix.
masked a section worst hit by rust.
(had been treated with phosphiric acid)
180 sandpaper lightly rough up.

spray direct onto pipe.

You can hardly see where I have sprayed ! ;D

The spray is superb and i will do my rear brake and gear lever with this
but prime first.

Good call on that spray !!!!!!!!
1977 RD250D (mechanical restore)
1980 GS550E
1982 GPZ750R1 (Restore)
1980 GSX250E (mechanical restore)
2002 Stihl FS55 Strimmer (mechanical restore)

Offline joolsuk

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Re: Surface rust on exhaust pipes
« Reply #10 on: July 14, 2019, 02:05:03 PM »
The Zinc spray is so good I am doing the other exhaust , which basically
future proofs them and is not visible as on underside. Well impressed.


I am also doing these bits i was gonna send off for Zincing....
1 primer then the Zinc spray. Will inform.
1977 RD250D (mechanical restore)
1980 GS550E
1982 GPZ750R1 (Restore)
1980 GSX250E (mechanical restore)
2002 Stihl FS55 Strimmer (mechanical restore)

Offline Astute Greaser

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Re: Surface rust on exhaust pipes
« Reply #11 on: July 14, 2019, 05:42:43 PM »
The Zinc spray is so good I am doing the other exhaust , which basically
future proofs them and is not visible as on underside. Well impressed.


I am also doing these bits i was gonna send off for Zincing....
1 primer then the Zinc spray. Will inform.

You can prime if you wish and use the zinc as top coat.
However it is a primer in its own right and using a different primer, you are creating a barrier thus preventing the electric potential between the zinc and the steel. The zinc is meant to sacrifice to the steel. You may which to use a top lacquer coat to improve the wear resistance.
The zinc paint has an additional feature in that it is electrically conductive so good for regulator boxes or earthing points.
Parts I have done on bike and cars (battery boxes and like) over the years just got zinc spray as primer then lacquer on top.
Find quote
Zinc-rich paints
These are paints in which very high levels of fine zinc dust have been incorporated. Because of the very high pigmentation with zinc particles , the dry film is electrically conductive and so acts to some degree as a metallic coating. Zinc dust paints can be applied to any rust and scale-free steel surface by brushing, spraying or dipping. They are mainly used to protect factory steel work, ship’s hulls and parts of car bodies and also to repair damage to other types of zinc coatings.

Automatic grit blasting and zinc dust paint spraying equipment are widely used in steel workshops and shipyards to protect steel plates during storage before fabrication and until application of the final coating system.

Offline joolsuk

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Re: Surface rust on exhaust pipes
« Reply #12 on: July 14, 2019, 06:09:35 PM »
I didn't know that..... damn I primed the parts today.
(not the exhausts mind ).
Ill clear coat them.

I am thinking of using the zinc spray on the underside
of the fuel tank (cheaper,  than my silver and not seen)
(no primer of  course)
Ill prob use on the inside (the side not seen) of the 2st oil tank too.
1977 RD250D (mechanical restore)
1980 GS550E
1982 GPZ750R1 (Restore)
1980 GSX250E (mechanical restore)
2002 Stihl FS55 Strimmer (mechanical restore)

Offline Astute Greaser

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Re: Surface rust on exhaust pipes
« Reply #13 on: July 14, 2019, 06:47:53 PM »
I'm not purest or rivet counter.
Your bike, if you're happy and it preserves the metal work, so you can enjoy the performance, go for it.
We've all got a few wrinkles.
Cheers
-Mike

Offline joolsuk

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Re: Surface rust on exhaust pipes
« Reply #14 on: July 14, 2019, 08:34:09 PM »
I for sure am no purest and aim one was to get bike running perfectly.
That done , with time on my hands I can turn to looks.
I find this the boring bit but makes a hell of a visual difference.
But it must be as it was visually and to save the bike hopefully forever.
This ain't no donor bike !

I definitely do not need genuine yam silver paint (my bike is silver)
so that Zinc it is underneath of tank.....unless my Mercedes silver
has a reprieve.
Halfords Merc silver is a superb substitute to original.


- don't go away as I am gonna start the tank project
so assistance might be needed.

- wheels now done - will post pic of rear when I take off
masking tape.
1977 RD250D (mechanical restore)
1980 GS550E
1982 GPZ750R1 (Restore)
1980 GSX250E (mechanical restore)
2002 Stihl FS55 Strimmer (mechanical restore)