View Full Version : preventing rust before paint?

08-18-2001, 12:29 PM
Anyone else notice the index dates are off and that new topics aren't being posted?

I sent Neil an email. What up?

03-03-2006, 07:31 AM
OK, so how do you restoration guys do it? I've been using the electrolytic rust removal thing. It works great by the way, along with ultrasonic cleaning. I've been spraying on WD40 immediately after water rinsing to keep the surface rust from instantly appearing. If I can't get back to it quick I follow w/LPS3 inhibitor.
Now the question: What do you do after you cleanup prior to painting to keep the surface rust from appearing? The preventatives need to be cleaned off or the paint/primer won't stick. The rust appears before I have a chance to hit it w/primer. Small stuff's OK, but bigger pieces are giving me problems.
Cadwiz in LA

03-03-2006, 07:44 AM
if you are getting rust after you have cleaned with electrolysis it is possible you need to keep it in longermuch longer.
leaving it to soak for awhile with the charger on doesnt hurt the part.
you should get a black oxide on the part ,which is almost protective
- well for a while,i have a couple of things knocking around that i have not gone further with,still black, no red rust despite the humidity,and handling ect.
I then use naval jelly, followed sometimes by zinc paint,orzinc chromate.
for bright stuff,i had an old bayonet i cleaned up and coated with danish oil ,no rust yet.

03-03-2006, 08:00 AM
I don't think it's the initial cleaning step. I have the black stuff coming out of the bath, rinse and brush/scotchbrite under water. Rust is gone and I get a nice finish which I can protect with WD40 or longer w/LPS3. It's after this step when I want to paint that the problem develops. I clean off the WD40/LPS3 with something like acetone or alcohol so the primer will stick. As soon as I do this the surface rust starts appearing (as in set the rag down, reach for the primer, look back and light rust is forming). I'm in south Louisiana so it's humid which compounds the problem. I just figured putting primer over very light surface rust would eventually lead to further rusting and paint flake problems. I was hoping you restoration guys had some fancy trick to prevent this.

03-03-2006, 08:21 AM
Cadwz...I also built an electrolytic cleaner.
You mentioned that you have the most problems with larger pieces.
It sounds to me that you need to leave them in the tank longer (as was mentioned above)
Ive done some truck parts that where rusted beyond belief. Some went through the tank two or three times before rust stopped popping out.
When I get them where I think the rust is gone, I coat them with a POR-15 product called "Metal Ready". Let it soak until it turns grey and is totally dry. Some areas need multiple treatments.
I neutralize the Metal Ready with distilled water and dry it with heat right away.
I don't have the humidity problem that you do so I'm not certain if this will help.

03-03-2006, 08:49 AM
using a junk 12 volt battery charger i get the impression that it just doesnt put out
the current needed for big bits.

I understand some people use a dc welder to get the current up .

I am always on the look out for a bigger 12 volt source but never find one.maybe one of the big wheel around battery chargers would work, though if has any fancy control electronics they need by passed

last part i did was an iron coupling that attaches the wet exhaust to the manifold ogf a marine engine, it took 5 days and 2 nights ,at 12v 10 amps on abattery charger, before it was inert-ie no more rust.to give some idea of time , this part was maybe 4 pounds.

Norman Atkinson
03-03-2006, 09:04 AM
I think that the cure is to phosphate items.
Traditionally, car bodies were de-rusted with a mixture of hydrochloric( muriatic) acid and phosphoric acid.
This appears in many tradenames but try it.Go to a vehicle finishers shop rather than a store. Again, omit the WD 40 for this.
Immediately, you should start overcoating!


J Tiers
03-03-2006, 09:11 AM
The rust issue is NOT pits....

I know what he is saying, the rust forms in dustty orange sheets all over the part right away. Rust isn't forming where it was, it is forming on a super-clean surface. "Flash rusting".

I end up wiping off that rust and going ahead with painting. Seems to work fine, nothing has popped out with big blisters under the paint.

That does not seeem to happen with phosphoric acid cleaning. It takes longer for rust to form, if you dry out the part it won't be a problem.

Seems to form the phosphate coating that Norman refers to, which used to be a normal part of auto body painting, before galvanized sheeting was used.

03-03-2006, 09:31 AM
J Tiers has it: "flash rusting" on highly active, newly cleaned surface is the problem. So far I think I've had good results for overall "crusty" rust removal in the tank for a few hours with small to medium parts. Overnight on one stubborn larger piece. Fixing to dump a drill press head (frozen quill) in the tank which will likely take a few days. I have a big battery charger with no amp problems so far, but the head will be the biggest thing I've tried. I think what I was looking for was validation from someone that wiping off the fine layer of flash rust then painting was OK.
Thanks for the replys

Norman Atkinson
03-03-2006, 10:20 AM
J et al,
I was aware of depositing an actual metal coating. I suggested a classic treatment knowing that most of us cannot emulate something better. With tongue in cheek, I moved the reader away from proprietory brand names and stuck for the basic gubbins!
So, kind sir, forgive the old fella'
Reading over my notes and others too, might I add that using a hot air gun will effectively dry out the phosphated coating prior to coating and give better rust proofing.

I did go off at a bit of tangent but this
rust proofing is not merely whopping a set of coats of primer, undercoat and finish.
Not in places where the metal moth has held
sway for a time. It gives me the opportunity to mention " lead loading" which I explained to my good friend BillyBoy a while back. Maybe the info is still around on file but most of us have to resort to a plastic filler to hide the pitting.Digressing, I am filling my very neglected Quorn Tool and Cutter grinder for a more posh coat or two of jollop.
It is important to add that many plastic
fillers are far from waterproof and consequently, can allow further rusting.
For my part, I rust proof, phosphate and then prime- and then fill- rub down and re-prime before the finish coats are applied.
Digressing further, I spray a mist coat of contrasting paint which shows up the hills and hollows after rubbing down.

Anyway, I hope that this adds a bit to the fund of knowledge for some.
Kind Regards


03-03-2006, 03:14 PM
Try using the acid to clean, rinse in water then immediately immerse the part in No-Rinse Tri Sodium Phosphate (TSP) or there is a no rinse TSP substitute at most paint places. You can take the part out of the TSP, compress air dry and you are ready for paint. The TSP will not promote rusting as opposed to the water creating the oxidation with the metal (iron oxide = rust). Just use gloves so your finger print oils does not get on the part.
It works for me. Does anybody else do this?

03-03-2006, 03:17 PM
<font face="Verdana, Arial" size="2">Originally posted by NORMAN ATKINSON:
J et al,
"... I am filling my very neglected Quorn Tool and Cutter grinder for a more posh coat or two of jollop."

Jollop? Huh? Norm I don't know you but I wish I did. You crack me up!

Lew Hartswick
03-03-2006, 05:29 PM
Two things occurr to me: 1 A small room with a
de-humidifier in it. 2 move to New Mexico where
the RH is usually around 6 to 15%. No problem.
:-) ...lew...

03-03-2006, 05:32 PM
I also protect sandblasted finishes with WD40 and just shoot the finish coat right on with no other cleaning. If the WD40 has "dried" where the surface is no longer wet, the paint or clear coat seems to stick just fine.

I cold blue a lot of stuff so I sand blast, dip in the cold blue, dip in alcohol to remove most of the water and finally spray with WD40. Right before top coat, I blast the part with compressed air to eliminate any trapped WD oil from crevices. If I want a more durable coat than the WD40, I spray urethane over it - I can't speak to your choice of top coat but you might want to try this method on a small piece.

Norman Atkinson
03-03-2006, 05:41 PM
I am now aware that the word " Jollop" has moved out of the English Language and has become the name of a dog who is apparently companion to someone called Engie Benjie.
Couldn't be more serious. You can buy
" Jollop" things for kids.
I've been Googling and identified a North East of England telephone number relating.
For JT, I should add that it refers to a place called British West Hartlepool.
Again, as JT is of Huguenot extraction, British West Harlepool was the scene of a shipwreck of one of Napoleon's Navy.
Only one person survived the storm and was captured and tried and duly hung as a French spy.
Later, it was discovered that the survivor was none other than the ship's pet monkey.

See what you lot missed!


03-03-2006, 05:51 PM
Simple answer. The part won't rust while it is wet, it needs oxygen and water. Keep the part wet as you clean it and as a last step rinse it with boiling water. Boiling water is deoxygenated. This will warm the part enough that no moisture will condense, even at the microscopic level. The part will quickly dry because of the retained heat but will still be warm enough to prevent rust from condensation for a short while, plenty of time to give it a shot of primer.

03-03-2006, 06:01 PM
For short term protection I've used a liquid phosphoric acid product...I can't remember the brand name at the moment. I would try a liquid product or something like this:


Forrest Addy
03-03-2006, 10:13 PM
You problem is the surface of the metal is somehow charged with rust promoting cooties by the rust removaal process. If you are treating the metal with an acid pickle you have to passivate it imeediately after. As it happens a hot solution of powdered laundry detergent with its high percentage of sodium carbonate scrubbed into the metal surface with a stiff brush works eliminates these rust promoting cooties (residual acid ions) as anythng you could get from a commercial metal treatment supply house.

For the last ten years I've been following up the hot degergent dip with a phosphoric acid metal prep solution like Jasco Metal Prep. This etches the metal a trifle, provides a rust resistant surface, and improves the paint grip. In an unheated shop, resistance to rust improves from mere seconds when fresh from the pickle to days after the passivation, to months with the metal prep.

All this is worked out by the paint, metal cleaning, and prep industry for generations. You can find some excellent advice if you Google under metal prep, rust prevention, and similar search objects.

03-03-2006, 10:43 PM
I use three drums.One for the electrolisis,one for a plain water rinse and the final is filled with Surprep 5 rust converter cut 10:1 with water.I just rinse the parts then dunk in the Surprep solution.Once it dries the parts will keep indoors indefinately.

03-03-2006, 11:39 PM
Darin beat me to it!

I skip the dips and put a 1/4 cup of phosforic acid in the electrolysis tank (5gal). I use the cheap Jebco, Jesco or something like that "metal prep" available at Home Depot, et al.

Don't over do it or your amps will skyrocket.

J Tiers
03-04-2006, 12:47 AM
<font face="Verdana, Arial" size="2">Originally posted by NORMAN ATKINSON:
Only one person survived the storm and was captured and tried and duly hung as a French spy.
Later, it was discovered that the survivor was none other than the ship's pet monkey.

See what you lot missed!


That was no monkey, that was my grandpappy's grandpa's second cousin!

He just looked, talked, and smelled like a monkey.... reckon that's because he stayed behind when we left http://bbs.homeshopmachinist.net//biggrin.gif

07-03-2007, 11:37 AM
My query is addressed mainly at you experts in, near or with connections with North East England:
I am told that the only solution to rust forming on / in my Cavalier rear wheel arches is to go for "lead loading", but that this may not be economic in view of the value of the car. Does anyone know anyone who does this in the North East? I am not a metal expert myself!


J Tiers
07-03-2007, 01:20 PM
Dunno, but I noticed the original poster seems to be from Louisiana.

That in and of itself is rust-creating.

Dry does not rust at least not fast. Humidity rusts.

I try to dry off parts right away, towel and hot air.

Humid areas will rust the metal and not a durn thing you can do but move.

UK is wet too, right?

07-03-2007, 10:07 PM
I fully understand your problem. It is related to where you live Clinton LA. Hot and Humid . Have same problem here Sport La but not as bad. Only solution is gray primer I buy it buy the 6 pack at wal mart. Face it metal rust down here.