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Lanchester 1953
Joined: 05 May 2016 Posts: 34
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Posted: Thu May 12, 2016 6:23 pm Post subject: using phosphoric acid |
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I have started de rusting with some phosphoric acid, but what is the right procedure?? do I let it dry and then paint, or wipe it with a wet cloth after it dries? should I dilute it? it is 80% and quite oily consistency . so far the rust has gone grey just like promised. |
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MikeEdwards
Joined: 25 May 2011 Posts: 2471 Location: South Cheshire
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Posted: Thu May 12, 2016 6:52 pm Post subject: |
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I've always painted it on, let it do its stuff, wire brush it, then wash it off and dry with a heat gun if necessary. Often I'll have to wire brush and re-apply quite often, depending on how bad the rust spot is. I did some on a tailgate a few weeks ago, I re-applied probably four or five times but it went from a rust spot to a pitted, but perfectly clean, area. |
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kevin2306
Joined: 01 Jul 2013 Posts: 1359 Location: nr Llangollen, north wales
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Posted: Thu May 12, 2016 7:41 pm Post subject: |
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I once had an old lister engine I was refurbing. Most of the bolts etc were crusty so I threw them in a bucket of phosphoric acid that I bought online, ready to use in a handy container.
Shortly after that I totally forgot about them until weeks after. Went to get them out to find the majority of the bolts had dissolved and were beyond use.
Great stuff but be careful and set a reminder somewhere
Kev |
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colwyn500
Joined: 21 Oct 2012 Posts: 1745 Location: Nairn, Scotland
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Posted: Thu May 12, 2016 10:47 pm Post subject: |
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kevin2306 wrote: |
Shortly after that I totally forgot about them until weeks after. Went to get them out to find the majority of the bolts had dissolved and were beyond use.
Great stuff but be careful and set a reminder somewhere
Kev |
Kev, those bolts couldn't have been steel. Phosphoric is very effective and I think it is the best rust REMOVER, but it stops after the rust has been "eaten".
Mike Edwards describes exactly my experience. Even better is if the item is removable and can be dropped in a bath of diluted acid.
Currently I am dipping some extremely rusty cowlings for an air-cooled engine and whilst some holes are appearing in the sheet-steel pressings, this is because there is no steel left in a few pitted areas.
I would say this is the best discovery I ever made in car restoration, which is why I go on about it so much. |
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MikeEdwards
Joined: 25 May 2011 Posts: 2471 Location: South Cheshire
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Posted: Fri May 13, 2016 10:04 am Post subject: |
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I must say that when it comes to dipping removable parts, I've been using Citric Acid and I think (though I couldn't say I've done proper tests, as I'm trying to get stuff done at the moment, rather than experiment) it works better than Phosphoric. Funnily enough I've never tried using citric to paint onto panels - I did read once that mixing it with wallpaper paste powder makes it into a gel that can allow it to be used in that way.
I took some headlamps to be plated recently, and on discussing the rust removal the chap told me he used Hydrochloric to de-rust before plating, so once I've got a bit more time I'll be trying that. |
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Lanchester 1953
Joined: 05 May 2016 Posts: 34
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Posted: Fri May 13, 2016 10:16 am Post subject: |
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colwyn500 wrote: | kevin2306 wrote: |
Shortly after that I totally forgot about them until weeks after. Went to get them out to find the majority of the bolts had dissolved and were beyond use.
Great stuff but be careful and set a reminder somewhere
Kev |
Kev, those bolts couldn't have been steel. Phosphoric is very effective and I think it is the best rust REMOVER, but it stops after the rust has been "eaten".
Mike Edwards describes exactly my experience. Even better is if the item is removable and can be dropped in a bath of diluted acid.
Currently I am dipping some extremely rusty cowlings for an air-cooled engine and whilst some holes are appearing in the sheet-steel pressings, this is because there is no steel left in a few pitted areas.
I would say this is the best discovery I ever made in car restoration, which is why I go on about it so much. | that sounds a bit like when certain people have dunked stuff in a caustic soda bath, only to find it had vanished later! I knew a person who cleaned his paintbrushes in caustic. It will remove aluminium powder from files, though. |
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kevin2306
Joined: 01 Jul 2013 Posts: 1359 Location: nr Llangollen, north wales
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Posted: Fri May 13, 2016 10:49 am Post subject: |
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colwyn500 wrote: | kevin2306 wrote: |
Shortly after that I totally forgot about them until weeks after. Went to get them out to find the majority of the bolts had dissolved and were beyond use.
Great stuff but be careful and set a reminder somewhere
Kev |
Kev, those bolts couldn't have been steel. Phosphoric is very effective and I think it is the best rust REMOVER, but it stops after the rust has been "eaten".
Mike Edwards describes exactly my experience. Even better is if the item is removable and can be dropped in a bath of diluted acid.
Currently I am dipping some extremely rusty cowlings for an air-cooled engine and whilst some holes are appearing in the sheet-steel pressings, this is because there is no steel left in a few pitted areas.
I would say this is the best discovery I ever made in car restoration, which is why I go on about it so much. |
they were old but being engine bolts I dont know what they were made of.
it was quite funny at the time to be honest
kev |
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petermeachem
Joined: 23 Sep 2013 Posts: 358 Location: Chichester Sussex
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Posted: Fri May 13, 2016 2:45 pm Post subject: |
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Phosphoric stops metal rusting until you get round to painting. Mine has been sat in the garage for a year or more, hopefully my health will improve to the point where I'll be able to progress it.
I used something called milkstone remover, used in dairies and very cheap from agricultural suppliers. Also does a cracking job on the kettle |
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Kleftiwallah
Joined: 27 Oct 2016 Posts: 222 Location: North Wiltshire
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Posted: Sat Apr 15, 2017 1:27 pm Post subject: |
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I was restoring my 1st Bonneville and I threw bits of carburettor in phosphoric acid. The following day there was just an assortment of brass fittings among the grey sludge! BEWARE
Cheers, Tony. |
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47Jag
Joined: 26 Jun 2008 Posts: 1480 Location: Bothwell, Scotland
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Posted: Sat Apr 15, 2017 1:55 pm Post subject: |
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Even molasses (treacle actually) will chew through steel if left long enough. I used a newish wood chisel to scrape crud off and I dropped it into the soup. I forgot all about it until the following spring and was draining the container when out fell a gnarled i.e. eating of metal with a plastic handle that I recognised.
Art |
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OuBallie
Joined: 02 Mar 2013 Posts: 225 Location: South Norfolk next to Suffolk
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Posted: Sun May 28, 2017 2:21 pm Post subject: Hydrochloriic fumes WILL rust bright metal |
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MikeEdwards wrote: |
I took some headlamps to be plated recently, and on discussing the rust removal the chap told me he used Hydrochloric to de-rust before plating, so once I've got a bit more time I'll be trying that. |
Mike,
Plus anyone else thinking of using this acid.
PLEASE, PLEASE DO NOT! use the stuff in an enclosed area as the fumes WILL RUST bright steel overnight.
I found this out to my cost in the 1970s, when every one of my machine tools was covered in surface rust, when I was dipping parts in the acid, in the garage.
Geoff - Mud Shields repaired, photos soon. _________________ Too many hobbies, not enough time!
1935 Austin Seven Ruby ARQ
1957 Austin A35 2-door
1967 Morris Minor 2-door
2007 Fiat Doblò MultiJet (It carries the spares etc)
Model Engineering |
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OuBallie
Joined: 02 Mar 2013 Posts: 225 Location: South Norfolk next to Suffolk
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Posted: Sun May 28, 2017 2:23 pm Post subject: Hydrochloriic fumes WILL rust bright metal |
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MikeEdwards wrote: |
I took some headlamps to be plated recently, and on discussing the rust removal the chap told me he used Hydrochloric to de-rust before plating, so once I've got a bit more time I'll be trying that. |
Mike,
Plus anyone else thinking of using this acid.
Please DO NOT use the stuff in an enclosed area as the fumes WILL RUST bright steel overnight.
I found this out to my cost in the 1970s, when every one of my machine tools was covered in surface rust, when I was dipping parts in the acid, in the garage.
Geoff - Mud Shields repaired, photos soon. _________________ Too many hobbies, not enough time!
1935 Austin Seven Ruby ARQ
1957 Austin A35 2-door
1967 Morris Minor 2-door
2007 Fiat Doblò MultiJet (It carries the spares etc)
Model Engineering |
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MikeEdwards
Joined: 25 May 2011 Posts: 2471 Location: South Cheshire
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Posted: Sun May 28, 2017 6:58 pm Post subject: |
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Thanks for the warning. I haven't got around to doing anything with it, or if I have, it's also good at wiping memories. |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4105 Location: South Cheshire
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Posted: Sun May 28, 2017 9:25 pm Post subject: |
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Hi
Phosphoric acid can be used diluted to 40% to act as a rust converter. I use it on every bit of steel that gets painted, even steel that looks perfect, the link is to an MGA body shell that had been professionally stripped just a few weeks earlier, the point being that corosion starts straight away. http://www.oldclassiccar.co.uk/forum/phpbb/phpBB2/viewtopic.php?t=6134&postdays=0&postorder=asc&start=15
I clean the residue (Iron Phosphate) off with panel wipe, as this also ensures any moisture is removed, and then paint immediately.
Don't leave it too long before painting; whilst the Phosphate coating will provide some corrosion protection, it is porous and moisture in the air will re-start the corrosion process , albeit slower and possibly not visible to the naked eye.
Dave |
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Brad1380
Joined: 28 Mar 2017 Posts: 5
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Posted: Mon Feb 26, 2018 9:07 pm Post subject: |
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I derust in a tank with washing up powder & a 12V supply.
Works well, would post a photo but Photobucket is broken. |
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