Using phosphoric acid on sheet steel
 

Hi all,

I have a steel BBQ which I am looking to derust using phosphoric acid. The acid is very runny and the BBQ far too big to dip it into a container of acid. I was wondering what the best method of "soaking" the BBQ in the acid so it would remove the rust. Some thoughts I had were.
1. put kitchen roll soaked in the acid on the surface
2. somehow thicken it (e.g. cornflour or something)
3. continually scrub it with a brush soaked in it

Anyone have any ideas / thoughts?

thanks

Lee.

Using phosphoric acid on sheet steel
 

On 23/08/2019 13:14, Lee Nowell wrote:
Hi all,

I have a steel BBQ which I am looking to derust using phosphoric acid. The acid is very runny and the BBQ far too big to dip it into a container of acid. I was wondering what the best method of "soaking" the BBQ in the acid so it would remove the rust. Some thoughts I had were.
1. put kitchen roll soaked in the acid on the surface
2. somehow thicken it (e.g. cornflour or something)
3. continually scrub it with a brush soaked in it

Anyone have any ideas / thoughts?

thanks

Lee.

Any of these work. Kitchen roll is good if you have a local area that is
particularly corroded.

Using phosphoric acid on sheet steel
 

On Fri, 23 Aug 2019 05:14:44 -0700, Lee Nowell wrote:

Hi all,

I have a steel BBQ which I am looking to derust using phosphoric acid.
The acid is very runny and the BBQ far too big to dip it into a
container of acid. I was wondering what the best method of "soaking"
the BBQ in the acid so it would remove the rust. Some thoughts I had
were.
1. put kitchen roll soaked in the acid on the surface 2. somehow thicken
it (e.g. cornflour or something)
3. continually scrub it with a brush soaked in it

Anyone have any ideas / thoughts?

The rust eater products used to come as a gel with a brush.
Fine for small to medium spot treatment.

You don't say how much rust there is to treat.

Worth considering using some strong plastic sheeting to rest the BBQ bits
on whilst you are treating them. Acid tends to rot most things it comes in
contact with, especially clothing.


Cheers


Dave R


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Using phosphoric acid on sheet steel
 

On Friday, 23 August 2019 14:39:58 UTC+1, David WE Roberts (Google) wrote:

Worth considering using some strong plastic sheeting to rest the BBQ bits
on whilst you are treating them. Acid tends to rot most things it comes in
contact with, especially clothing.

.... and teeth. Many fizzy drinks contain a significant amount of
phosphoric acid. Dentists use concentrated phosphoric acid to etch
the surface of cavities so as to improve the adhesion of composite
filling resins.
It also makes an excellent flux for soldering to stainless steel.

John

Using phosphoric acid on sheet steel
 

On 23/08/19 14:39, David wrote:

Worth considering using some strong plastic sheeting to rest the BBQ bits
on whilst you are treating them. Acid tends to rot most things it comes in
contact with, especially clothing.

It's not the rotting which would concern me - it's the splashing of the
ferric phosphate (formed when the rust reacts with the phosphoric acid).
Any porous surface, including clothing, wood, stone, etc will get
stained and such stains will never be able to be removed completely.

--

Jeff

Using phosphoric acid on sheet steel
 

On Friday, 23 August 2019 13:14:47 UTC+1, Lee Nowell wrote:
Hi all,

I have a steel BBQ which I am looking to derust using phosphoric acid. The acid is very runny and the BBQ far too big to dip it into a container of acid. I was wondering what the best method of "soaking" the BBQ in the acid so it would remove the rust. Some thoughts I had were.
1. put kitchen roll soaked in the acid on the surface
2. somehow thicken it (e.g. cornflour or something)
3. continually scrub it with a brush soaked in it

Anyone have any ideas / thoughts?

thanks

Lee.

Save your money next time, use HCl. HCl leaves a surface that rusts very quickly, it must be dried & coated right away when rinsed off.


NT

Using phosphoric acid on sheet steel
 

On 23/08/19 18:58, Chris Hogg wrote:
On Fri, 23 Aug 2019 18:38:47 +0100, Jeff Layman
wrote:

On 23/08/19 14:39, David wrote:

Worth considering using some strong plastic sheeting to rest the BBQ bits
on whilst you are treating them. Acid tends to rot most things it comes in
contact with, especially clothing.

It's not the rotting which would concern me - it's the splashing of the
ferric phosphate (formed when the rust reacts with the phosphoric acid).
Any porous surface, including clothing, wood, stone, etc will get
stained and such stains will never be able to be removed completely.


Hmmm...ferric phosphate is practically insoluble. That's not to say
that you wouldn't get bits of ferric phosphate flaking off the treated
sheet, but I doubt it would stain. And to do it properly, you should
wire-brush or otherwise abrade the steel first to remove loose bits.
The whole idea of treating rust with phosphoric acid is that the acid
reacts with the rust to give an insoluble, fairly impermeable skin on
the steel.

Indeed. There is little doubt about the "black" ferric phosphate being
completely insoluble. However, the Wikipedia article for ferric
phosphate says that the dihydrate has a solubility of about 0.67g/100ml,
which would be enough to make a stain mark. But how and under what
circumstances it is formed I haven't been able to establish. I might
have a play with some phosphoric acid rust remover and rusty nails to
see if the solution left on the surface of the blackened nails can stain
porous surfaces.

--

Jeff

Using phosphoric acid on sheet steel
 

Get it done by a company?
Buy a new one.
Brian

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"Lee Nowell" wrote in message
...
Hi all,

I have a steel BBQ which I am looking to derust using phosphoric acid. The
acid is very runny and the BBQ far too big to dip it into a container of
acid. I was wondering what the best method of "soaking" the BBQ in the acid
so it would remove the rust. Some thoughts I had were.
1. put kitchen roll soaked in the acid on the surface
2. somehow thicken it (e.g. cornflour or something)
3. continually scrub it with a brush soaked in it

Anyone have any ideas / thoughts?

thanks

Lee.

Using phosphoric acid on sheet steel
 

On Fri, 23 Aug 2019 05:14:44 -0700 (PDT), Lee Nowell
wrote:

Anyone have any ideas / thoughts?

Brush on, cover in clingfilm?


Thomas Prufer

Using phosphoric acid on sheet steel
 

On Fri, 23 Aug 2019 18:38:47 +0100, Jeff Layman
wrote:

On 23/08/19 14:39, David wrote:

Worth considering using some strong plastic sheeting to rest the BBQ bits
on whilst you are treating them. Acid tends to rot most things it comes in
contact with, especially clothing.

It's not the rotting which would concern me - it's the splashing of the
ferric phosphate (formed when the rust reacts with the phosphoric acid).
Any porous surface, including clothing, wood, stone, etc will get
stained and such stains will never be able to be removed completely.

?? As suppled phosphoric acid was clear. I can't recollect having my
clothing or cleaning materials stained.

It turns your fingers black after a while, but it's not permanent.

Not sure how it would work with a barbecue though. Phosphoric acid is
not used to remove rust. It is a rust "converter". The stuff turns the
oxide coating into a phosphate, preventing further corrosion. Whether
this would be effective on a sheet mild steel barbercue, I wouldnt
like to predict.

The adverts in the 70's told fibs incidentally, it does nor "turn rust
into good metal" :-)

AB

Using phosphoric acid on sheet steel
 

On Fri, 23 Aug 2019 12:08:58 -0700 (PDT), wrote:

On Friday, 23 August 2019 13:14:47 UTC+1, Lee Nowell wrote:
Hi all,

I have a steel BBQ which I am looking to derust using phosphoric acid. The acid is very runny and the BBQ far too big to dip it into a container of acid. I was wondering what the best method of "soaking" the BBQ in the acid so it would remove the rust. Some thoughts I had were.
1. put kitchen roll soaked in the acid on the surface
2. somehow thicken it (e.g. cornflour or something)
3. continually scrub it with a brush soaked in it

Anyone have any ideas / thoughts?

thanks

Lee.

Save your money next time, use HCl. HCl leaves a surface that rusts very quickly, it must be dried & coated right away when rinsed off.


NT
You must be some kind of masochist.

HCL is evil.

Maybe outside on a windy day with a full chemical suit etc.

AB

Using phosphoric acid on sheet steel
 

On 23/08/19 21:02, Jeff Layman wrote:
On 23/08/19 18:58, Chris Hogg wrote:
On Fri, 23 Aug 2019 18:38:47 +0100, Jeff Layman
wrote:

On 23/08/19 14:39, David wrote:

Worth considering using some strong plastic sheeting to rest the BBQ bits
on whilst you are treating them. Acid tends to rot most things it comes in
contact with, especially clothing.

It's not the rotting which would concern me - it's the splashing of the
ferric phosphate (formed when the rust reacts with the phosphoric acid).
Any porous surface, including clothing, wood, stone, etc will get
stained and such stains will never be able to be removed completely.


Hmmm...ferric phosphate is practically insoluble. That's not to say
that you wouldn't get bits of ferric phosphate flaking off the treated
sheet, but I doubt it would stain. And to do it properly, you should
wire-brush or otherwise abrade the steel first to remove loose bits.
The whole idea of treating rust with phosphoric acid is that the acid
reacts with the rust to give an insoluble, fairly impermeable skin on
the steel.

Indeed. There is little doubt about the "black" ferric phosphate being
completely insoluble. However, the Wikipedia article for ferric
phosphate says that the dihydrate has a solubility of about 0.67g/100ml,
which would be enough to make a stain mark. But how and under what
circumstances it is formed I haven't been able to establish. I might
have a play with some phosphoric acid rust remover and rusty nails to
see if the solution left on the surface of the blackened nails can stain
porous surfaces.

I just tried it with Loctite 7503 Rust Remedy. The stuff is a greyish
solution and stains by itself - never mind any rust! I did it by
touching the surface of cotton material and a piece of 15x38 pine with
the solution 15 seconds after applying it to the rusty surface. The
solution remaining on the converted "rust" left stains which were a lot
darker. BUT it took me some time to find that Loctite 7503 contains
tannic acid. There is no phosphoric acid in it at all!

So if anyone would like to repeat this with phosphoric acid and report
back, it would be interesting to see the result.

--

Jeff

Using phosphoric acid on sheet steel
 

On 24/08/19 09:40, Archibald Tarquin Blenkinsopp Esq wrote:
On Fri, 23 Aug 2019 18:38:47 +0100, Jeff Layman
wrote:

On 23/08/19 14:39, David wrote:

Worth considering using some strong plastic sheeting to rest the BBQ bits
on whilst you are treating them. Acid tends to rot most things it comes in
contact with, especially clothing.

It's not the rotting which would concern me - it's the splashing of the
ferric phosphate (formed when the rust reacts with the phosphoric acid).
Any porous surface, including clothing, wood, stone, etc will get
stained and such stains will never be able to be removed completely.

?? As suppled phosphoric acid was clear. I can't recollect having my
clothing or cleaning materials stained.

It turns your fingers black after a while, but it's not permanent.

No stain is permanent on the surface of skin as the cells are shed after
time, but the fact there was a stain at all is interesting. Have a look
at my reply to myself (to Chris Hogg's comment). If you've got something
rusty and phosphoric acid, it would be of interest to repeat what I had
tried3.

Not sure how it would work with a barbecue though. Phosphoric acid is
not used to remove rust. It is a rust "converter". The stuff turns the
oxide coating into a phosphate, preventing further corrosion. Whether
this would be effective on a sheet mild steel barbercue, I wouldnt
like to predict.

I would assume the ferric phosphate formed is heatproof to some extent.
I doubt it would stand up to any scraping though!

The adverts in the 70's told fibs incidentally, it does nor "turn rust
into good metal" :-)

Why am I not surprised?...

--

Jeff

Using phosphoric acid on sheet steel
 

"Archibald Tarquin Blenkinsopp Esq" wrote in message
...
On Fri, 23 Aug 2019 12:08:58 -0700 (PDT), wrote:

On Friday, 23 August 2019 13:14:47 UTC+1, Lee Nowell wrote:
Hi all,

I have a steel BBQ which I am looking to derust using phosphoric acid.
The acid is very runny and the BBQ far too big to dip it into a
container of acid. I was wondering what the best method of "soaking"
the BBQ in the acid so it would remove the rust. Some thoughts I had
were.
1. put kitchen roll soaked in the acid on the surface
2. somehow thicken it (e.g. cornflour or something)
3. continually scrub it with a brush soaked in it

Anyone have any ideas / thoughts?

thanks

Lee.

Save your money next time, use HCl. HCl leaves a surface that rusts very
quickly, it must be dried & coated right away when rinsed off.


NT
You must be some kind of masochist.

HCL is evil.

Maybe outside on a windy day with a full chemical suit etc.

You have never had a ****ing clue. It's routinely used to clean new
brickwork,
cleaning surplus mortar off the face bricks. No chemical suit ever used.

Lonely Psychopathic Senile Ozzie Troll Alert!
 

On Sun, 25 Aug 2019 07:15:22 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:

You must be some kind of masochist.

HCL is evil.

Maybe outside on a windy day with a full chemical suit etc.

You have never had a ****ing clue.

Oh, ****! And this innocent little thread was Rodent-free, so far! tsk

--
Marland answering senile Rodent's statement, "I don't leak":
"That¢s because so much **** and ****e emanates from your gob that there is
nothing left to exit normally, your arsehole has clammed shut through disuse
and the end of prick is only clear because you are such a ******."
Message-ID:

Using phosphoric acid on sheet steel
 

On Sat, 24 Aug 2019 15:30:10 -0700 (PDT), wrote:

On Saturday, 24 August 2019 10:43:25 UTC+1, Archibald Tarquin Blenkinsopp Esq wrote:
On Fri, 23 Aug 2019 12:08:58 -0700 (PDT), tabbypurr wrote:
On Friday, 23 August 2019 13:14:47 UTC+1, Lee Nowell wrote:

Hi all,

I have a steel BBQ which I am looking to derust using phosphoric acid. The acid is very runny and the BBQ far too big to dip it into a container of acid. I was wondering what the best method of "soaking" the BBQ in the acid so it would remove the rust. Some thoughts I had were.
1. put kitchen roll soaked in the acid on the surface
2. somehow thicken it (e.g. cornflour or something)
3. continually scrub it with a brush soaked in it

Anyone have any ideas / thoughts?

thanks

Lee.

Save your money next time, use HCl. HCl leaves a surface that rusts very quickly, it must be dried & coated right away when rinsed off.


NT
You must be some kind of masochist.

HCL is evil.

Maybe outside on a windy day with a full chemical suit etc.

AB

You certainly would need to do something that size outdoors :)
HCl is a joy to work with, results are almost instant. Last job I used it on the rust was gone in about 3 seconds, I wiped it off as I went to avoid excessive fume buildup (indoors).


NT

HCL is not nice. The finish is good, as you say.
Unless you then follow up with a lot of washing and tratment, the rust
will be back in no time.

Phosphoric acid is quick and I have had no trouble with fumes,
although I have stood next to a colleague who was finding the fumes
uncomfortable, yet I could genuinely smell nothing.

AB

Using phosphoric acid on sheet steel
 

On Saturday, 24 August 2019 10:43:25 UTC+1, Archibald Tarquin Blenkinsopp Esq wrote:
On Fri, 23 Aug 2019 12:08:58 -0700 (PDT), tabbypurr wrote:
On Friday, 23 August 2019 13:14:47 UTC+1, Lee Nowell wrote:

Hi all,

I have a steel BBQ which I am looking to derust using phosphoric acid. The acid is very runny and the BBQ far too big to dip it into a container of acid. I was wondering what the best method of "soaking" the BBQ in the acid so it would remove the rust. Some thoughts I had were.
1. put kitchen roll soaked in the acid on the surface
2. somehow thicken it (e.g. cornflour or something)
3. continually scrub it with a brush soaked in it

Anyone have any ideas / thoughts?

thanks

Lee.

Save your money next time, use HCl. HCl leaves a surface that rusts very quickly, it must be dried & coated right away when rinsed off.


NT
You must be some kind of masochist.

HCL is evil.

Maybe outside on a windy day with a full chemical suit etc.

AB

You certainly would need to do something that size outdoors :)
HCl is a joy to work with, results are almost instant. Last job I used it on the rust was gone in about 3 seconds, I wiped it off as I went to avoid excessive fume buildup (indoors).


NT

Using phosphoric acid on sheet steel
 

On Sunday, 25 August 2019 00:14:47 UTC+1, Archibald Tarquin Blenkinsopp Esq wrote:
On Sat, 24 Aug 2019 15:30:10 -0700 (PDT), tabbypurr wrote:
On Saturday, 24 August 2019 10:43:25 UTC+1, Archibald Tarquin Blenkinsopp Esq wrote:
On Fri, 23 Aug 2019 12:08:58 -0700 (PDT), tabbypurr wrote:
On Friday, 23 August 2019 13:14:47 UTC+1, Lee Nowell wrote:

Hi all,

I have a steel BBQ which I am looking to derust using phosphoric acid. The acid is very runny and the BBQ far too big to dip it into a container of acid. I was wondering what the best method of "soaking" the BBQ in the acid so it would remove the rust. Some thoughts I had were.
1. put kitchen roll soaked in the acid on the surface
2. somehow thicken it (e.g. cornflour or something)
3. continually scrub it with a brush soaked in it

Anyone have any ideas / thoughts?

thanks

Lee.

Save your money next time, use HCl. HCl leaves a surface that rusts very quickly, it must be dried & coated right away when rinsed off.


NT
You must be some kind of masochist.

HCL is evil.

Maybe outside on a windy day with a full chemical suit etc.

AB

You certainly would need to do something that size outdoors :)
HCl is a joy to work with, results are almost instant. Last job I used it on the rust was gone in about 3 seconds, I wiped it off as I went to avoid excessive fume buildup (indoors).


NT

HCL is not nice. The finish is good, as you say.
Unless you then follow up with a lot of washing and tratment, the rust
will be back in no time.

the metal needs coating quickly, leaving it to dry is too slow. There's only time for a quick rinse, a lot of washing guarantees rerusting.

Phosphoric acid is quick and I have had no trouble with fumes,
although I have stood next to a colleague who was finding the fumes
uncomfortable, yet I could genuinely smell nothing.

AB

HCl is agressive in that respect, but I find it no problem to manage.


NT