How to get rid of flas rust

[JimG1098]

Hi gang. Started media blasting the truck Project is going well. I am learning as I go. I blasted the engine, but I do not have the water pump installed. I put a garden hose in the water outlet of the engine to start it and move it out side,. Hence, I have some rust where the water splashis on the newly blasted engine.. Also, parts of the frame. What do I use to get rid of the rust. Also, Some spots I cant reach with the blaster. What degreaser should I use, so that paint will stick Then, What should I use to prime the engine befor paint. There have been lots of stuff mentioned, But I just dont know. Can I use the same stuff on the frame? Thanks, Jim G 1098

[AXracer]

You could use Naval Jelly on the flash rust, but that would mean rinsing with more water.
I'd probably use a rust converter instead.
I used Simple Green straight from the bottle in a spray bottle and a parts washing brush followed by a hot water rinse to remove grease. If the rinse water sheets off rather than beading up, the grease is gone. Be sure to scrape any caked on buildup off first.

Paint the engine with the same paint you would the body. Etching primer, epoxy primer, catalized single or two stage paint. Allow to dry for several days before starting engine.

[fatfenders]

You could use a metal prep product for the flash rust. Just acid you dilute. Picklex is a brand I see the pros talking about on paint forums. I've never used it. Modern epoxy primers stick so well that most painters I know don't even metal prep anymore before they prime. Everyone used to use the etching primer AX mentioned. It works well, but is thin and a pain to use without runs.

[AXracer]

You can get "Picklex" much cheaper by going to the pool supplies dept at Wally world and buying a container of "ph down" crystals aka sodium bisulfate, sodium acid sulfate or sodium hydrogen sulfate. Dissolve 1/2 cup in a gallon of water for your working solution. The solution is pretty acidic, so wear rubber gloves and a face shield when working with it. rinse off skin and clothing that received splashes with plenty of water, especially if the skin starts to itch or turn red.

[BlueOvalRage]

I've been using Ospho and have been exceedingly happy with the results. It's a phosphoric acid solution and chemically neutralizes the rust and protects the metal. It's also great if you have a bare section that you don't want to paint or primer for some time. It'll keep it from flash rusting in the mean time. I buy it at Ace hardware. About $12 a quart, but it's as thin as water, so it goes a loooong way.

[fatfenders]

Originally Posted by BlueOvalRage

I've been using Ospho and have been exceedingly happy with the results. It's a phosphoric acid solution and chemically neutralizes the rust and protects the metal. It's also great if you have a bare section that you don't want to paint or primer for some time. It'll keep it from flash rusting in the mean time. I buy it at Ace hardware. About $12 a quart, but it's as thin as water, so it goes a loooong way.

Thanks rage, I was trying to remember that brand name. They don't have it at my local store but I didn't check an Ace. Sounds like the stuff I used to buy from 3M at the paint store. It was phosphoric acid at twice the price.

Stuff AX posted probably work just fine too, even though it is a different type of acid. A chemist I is not. Have you ever used it for this purpose AX?

[JimG1098]

Thanks gang, you guys and girls on this forum are the very best.

I'll get on it this weekend

Jim G 1098

[Dr G]

Being somewhat new to rust, I find these threads very interesting, yet somewhat confusing.

All my life, if you had a rusty part, you'd whip out a can of Rustoleum, and you were in business.

Then somewhere along the way I heard about POR-15, and have used that on a few parts, though probably not correctly.

Now I learn about rust inhibitors, rust preventing primers, epoxy primers, acids etc... Phew!

I can appreciated that if you have rusty suspension part you want to preserve, then the materials and methods used might be different than for, say, a rusty fender. But at this point it is not clear to me when and where to use these various products.

I'll just keep reading and learning.

Gustave

[fatfenders]

Originally Posted by Dr G

Being somewhat new to rust, I find these threads very interesting, yet somewhat confusing.

All my life, if you had a rusty part, you'd whip out a can of Rustoleum, and you were in business.

Then somewhere along the way I heard about POR-15, and have used that on a few parts, though probably not correctly.

Now I learn about rust inhibitors, rust preventing primers, epoxy primers, acids etc... Phew!

I can appreciated that if you have rusty suspension part you want to preserve, then the materials and methods used might be different than for, say, a rusty fender. But at this point it is not clear to me when and where to use these various products.

I'll just keep reading and learning.

Gustave

Gustave,

When I have my choices, I always remove rust with a media/sand sandblaster, or sometimes a DA sander. Covering up rust with rustoleum is OK for a wheelbarrow, but not my truck. Nothing against rustoleum. I like it well enough for fuel tanks, bottom of the truck etc. Undercoat sticks to it particularly well. We could type for hours on the subject. This thread is about bare metal that was cleaned, and then got wet so it has surface rust in hard to get at places. An acid bath will clean it up and re-prepare it for paint. You can also try to encapsulate rust with POR-15. It is not a method I will ever use, but there are some fans on this forum.

Next time you want to clean and repaint something, don't be afraid to start a thread. We'll give you more opinions that you know what to do with.

[AXracer]

Dewayne,
yes, I have used it. We used it in the jewelry studio all the time for removing heat oxidation and flux from soldering on non ferrous metals (we never mixed ferrous and non ferrous metals in the same solution if you did a chemical reaction would copper plate all the pieces in the solution). In the jewelry studio it is refered to as "pickle" and we kept a crock pot full of the heated solution on each bench. I've also used used it for removing rust on iron and steel and even dissolving broken wire drill bits out of a piece of gold or platinum I was drilling. It will etch the steel pretty quickly so it is used cold as a wipe or dip and rinsed ("killed") with a baking soda solution. For that reason never soak a machined part such as a wheel cylinder without protecting the machined surfaces. It will remove the rust from a cast exhaust manifold in an hour or two (protect the flange surface with a covering of duct tape) so don't leave parts soaking unattended for long periods. It's cheap enough to make a large bath of it. Dispose of down the drain followed by plenty of cold water, it's also a good drain cleaner. If you want to save the mixed solution, put it in a sealed airtight plastic container. Yes, I was a chemist in a previous life.


Dr G,
Rustoleum was and is a fine product, but it doesn't really change the rust, just gives it a somewhat moisture resistant coating (many paints are not moisture resistant). Rust, or iron oxide is very hygroscopic (absorbs moisture from the air) and is therefore self perpetuating even when overcoated with paint. Unless completely and entirely removed the rust will continue to grow and soon pops thru the coating. As soon as the coating is broken, the rust grows vigorously from that point. Salt is also very hygroscopic and readily stick to rust, so it helps form a bridge for moisture penetration and reaction. Bottom line is you can't stop rust by covering it up.
Sanding a rusted surface helps, but unless you sand away a layer of metal deeper than any pits or pock marks you leave rust in those recesses and it eventually returns. Wire brushing is better than sanding, but only if the wires are fine enough and stiff enough to reach the bottoms of the pits, so it is unlikely to be 100% sucessful in removing existing rust. Sand blasting is better yet assuming the media is friable (breaks into finer particles on impact) enough to form fine enough particles to reach into the bottoms of the smallest pits and the pressure is high enough to knock out the iron oxide (but not so high as to warp the metal). Any metal that has been sandblasted, sanded or wire brushed exposes a lot of surface area to the air so must be handled with clean cotton or rubber gloves and immediately covered on all sides with a rust and/or moisture inhibitor such as a catalized epoxy primer or chemical treatment until painted.
There are a few different products on the market that react chemically with the metal and/or iron oxide to offer temporary to semipermanent rust inhibition.
Ospho or other phosphoric acid based products are a temporary protectant. They combine with any iron oxide that has come in contact with moisture to form a more oxidation resistant compound. This protection can be wiped or washed off the surface, so should be used for short periods of protection or in conjunction with sealing the parts airtight in a plastic bag or wrap (try the new Glad "press and seal" wrap it really does readily seal air tight and is pretty tough).
POR is billed as a "rust encapsulator" AFA I can gather it combines a rust inhibiting layer similar to rustoleum with an airtight polymer surface coating. I have not used it but it seems to get good reviews from those who have. Hasn't been on the market long enough to determine the long term effectiveness. It is not promoted AFAIK as a finished surface undercoating under standard paints, so you would still need to use a different product for exteriors of body panels etc.
Rust converters is another class of products that are water thin and wiped on a rusty surface that has first been stripped of loose scale. It chemically reacts with any remaining iron oxide it contacts to form a hard black compound that is no longer iron oxide and does not have IO's hygroscopic nature nor does it continue to oxidize. It has no affect on clean oxide free metal. It requires no rinsing or "killing" and after drying for 24 hrs it can be painted over with primer or paint, it actually promotes adhesion of those coatings. This is the most effective and permanent product/process out there and can be used on both underpanels and exterior surfaces without affecting paints. This is the class of products I use. I buy it under the Red Devil brand in a plastic squeeze bottle with a fuzzy nylon applicator stuck to the outside in the painting chemicals area of Lowes and Home Depot. It's not real cheap but goes a long ways so is price effective.
PS: wear rubber gloves when using converters, they will also react with the iron compounds in your skin forming a similar black coating on your fingers that is difficult to remove.

[BlueOvalRage]

It would be of little value on a large assembly like the OP's, but for smaller parts, I swear by rust removal via the electrolysis method. Google it for a detailed desciption. It has been documented in several places on the net. It's easy, mess-free, and the only biproduct is rusty, soapy water. It basically consists of a plastic container large enough to submerge all of or at least half of your part, a battery charger, some sacrificial scrap metal and a water/washing soda solution. It duplicates the electrical process that causes rust in reverse and converts it back to a steel compound in the form of a black coating. This coating washes right off with a scotch brite pad under hot water. It'll also strip most paints and undercoating, too. After the part is cleaned and derusted, I coat it with Ospho and it's ready to paint. If the electrolysis followed by Ospho won't kill it, then the part is probably too rusted to try to save.