Using Harpic 10x (Hydrochloric acid based) to clean downpipes...

[Grahamm]

(I've posted this in a few places on Facebook as well, so sorry if some people see this more than once.)

Ok, I've been recommending that people *don't* use Harpic to clean their downpipes because it is not good for stainless steel. (See https://www.bssa.org.uk/topics.php?article=30 for example)


 But, since I've got an old FZ6 engine in my shed (replaced after the big end failed) and it's got rusty pipes, I've decided I'm going to put my money where my mouth is and see what actually happens.


 So the idea is to clean Pipe 1 with Autosol, Pipe 2 with Harpic and leave it on. Pipe 3 with Harpic and wash it off with distilled water and possibly leave Pipe 4 as it is. Then I'll spray them all with a salt water solution (to represent riding on roads in the winter) and leave them for a while to see what happens.


ADDENDUM: To clarify, based on a couple of comments I've received, the idea is to see if they are *more likely* to corrode after the Harpic treatment than with eg Autosol.


 Does anyone have any (helpful!) comments on my scientific method? Anything else/ better I could try on Pipe 4 instead of leaving it as a control?


Useful suggestions would be welcomed.

[agricola]

I have heard that ali foil can be used to remove rust and improve the finish, with a little white vinegar

[Dudeofrude]

If the pipe is actually rusty then spraying a good dose of ACF50 and leaving it, as that is meant to actively neutralise rust 🤷‍♂️

[fazersharp]

If the pipe is actually rusty then spraying a good dose of ACF50 and leaving it, as that is meant to actively neutralise rust 🤷‍♂️

I do this in the winter after a ride onto the collector box and the "balance tubes - seem to be a problem point winter because the bike is likely to be layed up for a few weeks but the problem is on the pipes it burns off. I get to my firts set of traffic lights and it looks like the bike is on fire with all the smoke 
 
 And why are stainless steel pipes rusting ?

[agricola]

If the pipe is actually rusty then spraying a good dose of ACF50 and leaving it, as that is meant to actively neutralise rust 🤷‍♂️

I do this in the winter after a ride onto the collector box and the "balance tubes - seem to be a problem point winter because the bike is likely to be layed up for a few weeks but the problem is on the pipes it burns off. I get to my firts set of traffic lights and it looks like the bike is on fire with all the smoke 
 
 And why are stainless steel pipes rusting ?

My understanding is that they are made from a less expensive type of St Sl, and they take on a brownish, rusty looking tinge. Personally, Id never go anywhere near putting Harpic x10 on any bike of mine, for fear of getting it on other parts etc. Each to their own

[darrsi]

Use 2 pairs of rubber gloves and protective glasses!

[Grahamm]

And why are stainless steel pipes rusting ?

Stainless steel is only corrosion *resistant*, despite what the name suggests.

The point of this, though, is to find out whether using Harpic is, in the long run, actually a good idea or a bad one. I believe that using a hydrochloric acid based cleaner will leave them more prone to corrosion after use, that's what I'm trying to test.

It has been pointed out elsewhere that, for instance, it won't be a perfect test because there won't be hot gases running through the pipes, but since all the pipes will be under the same conditions, thet shouldn't entirely nullify the results.

So what I'm looking for is for any other problems with the methodology of testing, rather than better techniques for cleaning them etc.

 

[Grahamm]

Use 2 pairs of rubber gloves and protective glasses!

That's my normal attire...

[mtread]

Isn't autosol a polish, as well as a cleaner? So it will leave a protective barrier, which of course harpic won't? So not really a fair comparison?


I must admit I have used harpic on my Tiger. Triumph pipes are notorious for discolouring, and harpic restores them to their stainless state. But guess what, after rinsing and drying..... I then apply some autosol 


I certainly wouldn't risk not rinsing the harpic off!


So looks like you need a 5th pipe - Harpic + Autosol 

[darrsi]

OPTIGLANZ


http://foc-u.co.uk/index.php?topic=8580.25

[fazersharp]

A good simple test for stainless steel is to see if a magnet will stick, if it will not stick it is a good grade if it will stick then - not so good quality, and you can actually feel the strength of the stick on different grades.   

[Grahamm]

Isn't autosol a polish, as well as a cleaner? So it will leave a protective barrier, which of course harpic won't? So not really a fair comparison?

If you search for "how do I clean my downpipes", generally Autosol and Harpic are the two answers you get.

But the aim is to see which one is less resistent to corrosion after treatment.

So looks like you need a 5th pipe - Harpic + Autosol 

I'm thinking that, rather than leaving Pipe 4 as a control, I might do Harpic + Autosol.

[Grahamm]

A good simple test for stainless steel is to see if a magnet will stick, if it will not stick it is a good grade if it will stick then - not so good quality, and you can actually feel the strength of the stick on different grades.   

I believe that's not entirely correct.

316 and 304 (which is, I believe what the FZ6's pipes are made from) are, from what I understand, "non-Austenitic" stainless steel, ie they are magnetic, even though most grades of stainless steel aren't.

It is possible for the magnetic permeability of austenitic steels to be changed during processing. For example, cold work and welding are liable to increase the amount of martensite and ferrite respectively in the steel. A familiar example is in a stainless steel sink where the flat drainer has little magnetic response whereas the pressed bowl has a higher response due to the formation of martensite particularly in the corners.

https://www.bssa.org.uk/faq.php?id=24

Of course if you've got cheap "stainless" steel which is just plated, that's a different matter entirely...!

[pilninggas]

I used Harpic on my FZ1S' exhaust a few years ago. I too was interested to see if it sped up future corrosion.


It really does get them gleaming and it didn't seem to induce accelerated corrosion afterwards. Do take care though, it is hydrochloric acid [as stated above] and is pretty strong. Have goggles and a ready source of water on hand.

[darrsi]

I just used Harpic to clean my exhaust, I've used it before and it does work well.
As I'm not using the bike right now I saturated a rag with WD40 and wiped the whole exhaust with it afterwards.
No doubt it's going to smell a bit funky for a while when I do start it up next time. 

[ogri48]

a gallon of brick cleaner from the builders yard is a cheaper way to get hydrochloric acid. cement is strongly alkaline, so the acid cleans tools/bricks/slabs etc brilliantly. I used some to clean some badly cement grouted quarry tiles years ago, and where i accidently brushed against the old 15mm copper central heating pipes, they instantly looked as bright and shiny as new. I clean my trowel with it from time to time, but you have to straightaway not only wash the metal in water thoroughly, but also dry it and apply/wipe it over with wd40 or summat. if you dont, it actually rusts before your eyes in minutes. bizarre. if you clean a alu level with it you have to be even quicker, as it dissolves the aluminium. id clean the pipes with it occasionally taking the necessary steps afterwards, but i wouldnt make habit of it. Its kind of like ifyou t-cut paintwork...you gotta get good polish on it staight away or it will fade again very quickly because of the ammonia, hence ive only t cutted my van once in the five years ive had it, but i use a good polish (colour magic) every winter and lots of elbow grease to bring the original colour out

[Dudeofrude]

So did you manage to complete the experiment Graham?
I'm rather interested in the results as I removed my headers the other day so now have the opportunity to give then a proper clean.
Would be nice to get them as close to 'new' looking as possible

[fazersharp]

a gallon of brick cleaner from the builders yard is a cheaper way to get hydrochloric acid. cement is strongly alkaline, so the acid cleans tools/bricks/slabs etc brilliantly. I used some to clean some badly cement grouted quarry tiles years ago, and where i accidently brushed against the old 15mm copper central heating pipes, they instantly looked as bright and shiny as new. I clean my trowel with it from time to time, but you have to straightaway not only wash the metal in water thoroughly, but also dry it and apply/wipe it over with wd40 or summat. if you dont, it actually rusts before your eyes in minutes. bizarre. if you clean a alu level with it you have to be even quicker, as it dissolves the aluminium. id clean the pipes with it occasionally taking the necessary steps afterwards, but i wouldnt make habit of it. Its kind of like ifyou t-cut paintwork...you gotta get good polish on it staight away or it will fade again very quickly because of the ammonia, hence ive only t cutted my van once in the five years ive had it, but i use a good polish (colour magic) every winter and lots of elbow grease to bring the original colour out

I had a brick I needed to clean off some cement and harpic worked a treat. Thanks to your post Orgi48 

[ogri48]

  btw its ogri not orgi...

[fazersharp]

btw its ogri not orgi...

Thats the thing with users names you have to look very carefully when spelling them and sometimes have to scroll back down to find them 
Dudeofrude, I always read as Deffodude.
pilninggas - another tricky one to spell out from memory

[Dudeofrude]

btw its ogri not orgi...

Thats the thing with users names you have to look very carefully when spelling them and sometimes have to scroll back down to find them 
Dudeofrude, I always read as Deffodude.
pilninggas - another tricky one to spell out from memory

Haha I've used this alias online since about 2002. Its Dude Of Rude (actually got it from the front cover of a kerrang magazine about Fred Durst) but the amount of people that think its Dudeo Frude 😅😅

[Dudeofrude]

Well cant argue with the results of using harpic.... this is after a wash, decrease then treatment with the Harpic.
It's about the 5th time I've used it and I cant see any signs of abnormal corrosion.
They dont look a nice as I'd hoped but still a lot better

[fazersharp]

Your grass needs cutting 

[Dudeofrude]

Your grass needs cutting 

Your right but I missed the last brown bin collection so I have nowhere to put the cuttings till next week 😅

[vinnyb]

Your grass needs cutting 

Your right but I missed the last brown bin collection so I have nowhere to put the cuttings till next week 😅

https://www.popularmechanics.com/science/animals/a19550487/dont-mow-your-lawn-and-help-save-the-bees/