classic car forum header
Classic cars forum & vehicle restoration.
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
Register     Posting Photographs     Privacy     F/book OCC Facebook     OCC on Patreon

Metalwork/rust treatment
Goto page 1, 2  Next
Post new topic   Reply to topic    Classic cars forum & vehicle restoration. Forum Index -> Bodywork & Paint Restoration
Author Message
rcx822



Joined: 31 Dec 2010
Posts: 112

PostPosted: Tue May 31, 2016 12:38 pm    Post subject: Metalwork/rust treatment Reply with quote

I've read a few posts and articles on dealing with rust already, but if anyone can point me to any more good ones I'd be grateful.

With using phosphoric acid to remove rust, is there any way of thickening it or using an alternative, so that it can be used on vertical surfaces and small areas that could be done "in situ" ?

When treating inside of box sections, so I understand that there's no way to clean and derust in there? So are the anti corrosion agents really strong enough to stop the spread of rust if they are blindly sprayed on uncleaned surfaces that may already have flaking paint or surface rust in there? Maybe it depends on how bad things are in the box sections?

I always thought that rust had to be entirely removed to stop it spreading but somehow all these classics are being preserved when I'm sure they all have box sections that rust from the inside.

I looked at e-coating but there's quite a few posts online saying that seams would start rusting just a few years after e-coating. I also think there's only one plant in the UK and they have a 135cm height limit which I'm well above.
Back to top
View user's profile Send private message
Phil - Nottingham



Joined: 01 Jan 2008
Posts: 1252
Location: Nottingham

PostPosted: Tue May 31, 2016 6:19 pm    Post subject: Reply with quote

If anyone found one that worked it would be suppressed. Bare and even new steel has inherent tendencies to rust any post manufacturing application is doomed to failure especially in the damp & wet UK

Modern cars (=2000 on) have really excellent paint protection that stops the wafer thin steel corroding. A modest chip/scratch in its tough but flexible coating leads to rapid corrosion although with less tendency to creep underneath but it will do eventually. Older cars have much greater thickness but far inferior, if any at all corrosion protection

In the 50 years I have tried everything - the best way is too cut out corroded steel and replace with new. This still will rust however - I ham on 3rd & 4th times repairs with either method
_________________
Rover P2
Rover P4
Rover P5 & P5B
Land Rover S2 & S3
Morris Mini Traveller Mk2
Back to top
View user's profile Send private message Send e-mail
MikeEdwards



Joined: 25 May 2011
Posts: 2463
Location: South Cheshire

PostPosted: Tue May 31, 2016 7:10 pm    Post subject: Reply with quote

I've read that mixing phosphoric acid with wallpaper paste can be a good way to make it work on vertical surfaces, but I've never tried it. One of the packaged products comes as a gel, that worked quite well for me but I can't remember the name of it.
Back to top
View user's profile Send private message Visit poster's website
Bitumen Boy



Joined: 26 Jan 2012
Posts: 1733
Location: Above the snow line in old Monmouthshire

PostPosted: Tue May 31, 2016 7:28 pm    Post subject: Reply with quote

MikeEdwards wrote:
I've read that mixing phosphoric acid with wallpaper paste can be a good way to make it work on vertical surfaces, but I've never tried it. One of the packaged products comes as a gel, that worked quite well for me but I can't remember the name of it.


One thing that does work is using it to stick tissue paper to the panel - just with the wetness of it - then building up the thickness as necessary. Cheapy loo roll or similar works fine.
Back to top
View user's profile Send private message
Lanchester 1953



Joined: 05 May 2016
Posts: 34

PostPosted: Wed Jun 22, 2016 9:57 pm    Post subject: Reply with quote

put some phosphoric acid in an old hand spray gun like a bug spray for plants and squirt it as a mist. You can also use an air pressure spray to blow it inside panels, chassis sections, doors etc. Then either paint over or spray with Waxoil, or any other sealant.
Back to top
View user's profile Send private message
Miken



Joined: 24 Dec 2012
Posts: 544

PostPosted: Tue Oct 18, 2016 8:22 pm    Post subject: Rust treatment (yet again) Reply with quote

This may be of interest.
I found this picture of a bit I cut off and discarded from my old Morris when I was renovating the front wings. You can see that part of it has been shot blasted'
Before I cut it off, the entire wing was sprayed with this product:

http://www.frost.co.uk/por15-prep-metal-ready.html

Normally shot blasted steel will, quite literally, rust before your eyes if you take it outside on a damp day. I found this off-cut in my garden where it had lain in all weather (admittedly it was summer) for about 7 weeks. There is hardly any new rust formed on the blasted area apart from the edge where I hack sawed it off. Apologies if this sounds like and advert, but I was genuinely surprised and please to find the part had been protected so well.
Mike


Back to top
View user's profile Send private message
rcx822



Joined: 31 Dec 2010
Posts: 112

PostPosted: Fri Oct 28, 2016 1:18 pm    Post subject: Reply with quote

Quote:
This may be of interest.
I found this picture of a bit I cut off and discarded from my old Morris when I was renovating the front wings. You can see that part of it has been shot blasted'
Before I cut it off, the entire wing was sprayed with this product:

http://www.frost.co.uk/por15-prep-metal-ready.html

Normally shot blasted steel will, quite literally, rust before your eyes if you take it outside on a damp day. I found this off-cut in my garden where it had lain in all weather (admittedly it was summer) for about 7 weeks. There is hardly any new rust formed on the blasted area apart from the edge where I hack sawed it off. Apologies if this sounds like and advert, but I was genuinely surprised and please to find the part had been protected so well.
Mike


Thanks I took a look at this product. I've read about zinc phosphate, which this uses, it's used as temporary rust prevention. I'd be interested if it's presence adversely affect the adhesion of the primer that would then go on top.

In the end I've decided to go with Jotun epoxy primer and topcoat. It's similar to Epoxy Mastic 121 but much cheaper as it's sold for industrial purposes. Only problem is that manufacturer says it should be applied by airless spray which is a problem as airless sprayers can't have the spray coverage set low and have big hopppers so are no good for painting car parts that are relatively small. But people are ignoring this, thinning it out, and applying with a LSPV spray gun set to 50psi (i.e. double what LSPV should use), which appears to work.
Back to top
View user's profile Send private message
colwyn500



Joined: 21 Oct 2012
Posts: 1745
Location: Nairn, Scotland

PostPosted: Fri Oct 28, 2016 8:18 pm    Post subject: Reply with quote

[quote="rcx822"]
Quote:


Only problem is that manufacturer says it should be applied by airless spray .


In most applications it's actually better to apply epoxy by brush because it needs a relatively thick coating in order to allow it sufficient time to cure. It also allows the paint to be pushed into awkward areas or crevices.
Airless allows high volumes and minimal thinning.
Thinners obviously make it spead thinly with the risk that it will simply dry by evaporation before it gets the chance to cure and properly bond tothe metal surface.
Back to top
View user's profile Send private message Send e-mail
rcx822



Joined: 31 Dec 2010
Posts: 112

PostPosted: Fri Oct 28, 2016 8:50 pm    Post subject: Reply with quote

colwyn500 wrote:

In most applications it's actually better to apply epoxy by brush because it needs a relatively thick coating in order to allow it sufficient time to cure. It also allows the paint to be pushed into awkward areas or crevices.
Airless allows high volumes and minimal thinning.
Thinners obviously make it spead thinly with the risk that it will simply dry by evaporation before it gets the chance to cure and properly bond tothe metal surface.


Finally an explanation why they don't recommend air spray!
What if I brush on and then sand smooth before top coat? I tried brush but the finish showed brush strokes. Jotun says topcoat can be sprayed.
Back to top
View user's profile Send private message
colwyn500



Joined: 21 Oct 2012
Posts: 1745
Location: Nairn, Scotland

PostPosted: Fri Oct 28, 2016 9:59 pm    Post subject: Reply with quote

rcx822 wrote:

What if I brush on and then sand smooth before top coat? I tried brush but the finish showed brush strokes. Jotun says topcoat can be sprayed.


It is impossible to brush on the epoxy without it dragging and leaving brush-strokes. It is also very important to give it at least two coats and the second needs to be done relatively promptly, say withing about 12 hours of the first. This is because if the curing process goes on for too long, an external layer will prevent full adhesion. This applies equally to any additional coats of conventional air-drying paint that you obviously intend to to put over the epoxy.
So sanding out any brush marks is a good idea because it also breaks down that layer allowing the next coats to adhere properly. The sanding should be done imediately prior to overpainting otherwise a new, cured coat will form.
I would go with a relatively light sanding with something like 320 grit and use a good high-build primer to take out any remaining imperfections. Apart from the fact that epoxy is not the best product to sand down, there is the risk that you may oversand the epoxy and reduce its effectiveness.
I have found that over most of my car body which was painted with epoxy over bare steel treated with phosphoric acid and then wiped down with a "desalting" liquid, it is almost as if it hs been galvanised.
I used a conventional spray but with a big nozzle and just enough of the correct No. 17 thinners to get it out of the gun.
Back to top
View user's profile Send private message Send e-mail
rcx822



Joined: 31 Dec 2010
Posts: 112

PostPosted: Sat Oct 29, 2016 9:05 am    Post subject: Reply with quote

Good sounding advice Colwin. How did you learn this?

I bought the winter grade paint as it gets cold some nights. Winter grade can be applied in colder conditions. Also got ano infrared heater and connecting it to a thermostatic switch to keep the temp above 10 degrees.
Back to top
View user's profile Send private message
colwyn500



Joined: 21 Oct 2012
Posts: 1745
Location: Nairn, Scotland

PostPosted: Sat Oct 29, 2016 3:57 pm    Post subject: Reply with quote

rcx822 wrote:
Good sounding advice Colwin. How did you learn this?

I bought the winter grade paint as it gets cold some nights. Winter grade can be applied in colder conditions. Also got ano infrared heater and connecting it to a thermostatic switch to keep the temp above 10 degrees.


Very Happy I'm good at reading product information sheets and there is a lot on the "Rustbuster" website.
I also found that experience backed up all of the directions and I did make the odd mistake at first. Rolling Eyes
Back to top
View user's profile Send private message Send e-mail
rcx822



Joined: 31 Dec 2010
Posts: 112

PostPosted: Sat Oct 29, 2016 4:17 pm    Post subject: Reply with quote

I read the Jotun application guides and it didn't say a lot of that though. Rust busters don't have an application guide at all! No specification on time between coats, min temperatures etc. They seem a lot more casual about it. That's why I went for Jotun, they are far more specific and also much cheaper.

Rust busters did say that their Epoxy Mastic 121 can be heated to thin it. I'm thinking of buying one of those little single electric pods, could use it to heat paint and also for heating caustic soda for decreasing small parts prior to zinc plating or painting.
Back to top
View user's profile Send private message
colwyn500



Joined: 21 Oct 2012
Posts: 1745
Location: Nairn, Scotland

PostPosted: Sat Oct 29, 2016 7:30 pm    Post subject: Reply with quote

rcx822 wrote:



Rust busters did say that their Epoxy Mastic 121 can be heated to thin it. .


You did the right thing because I read that Rustbuster may be a repackaged Jotun product anywayalthough i can't verify that I just keep dowloading product sheets to gather info and Jotun are great at that.
Back to top
View user's profile Send private message Send e-mail
rcx822



Joined: 31 Dec 2010
Posts: 112

PostPosted: Sat Oct 29, 2016 7:42 pm    Post subject: Reply with quote

Meant to say I'm thinking of getting a mini electric hob to heat paint and for hot degreasing.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Classic cars forum & vehicle restoration. Forum Index -> Bodywork & Paint Restoration All times are GMT + 1 Hour
Goto page 1, 2  Next
Page 1 of 2

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
OCC Merch link
Forum T&C


php BB powered © php BB Grp.