Phosphoric acid question

[RockHillWill]

The biggest advantage that I can see from several years of using the molasses, was that I was able to accumulate a large collection of copperhead and rat snakes as well as two families of raccoons and several hoards of bees. It stunk after setting for a few weeks and was difficult to remove the residue from inside of cylinder heads and hit and miss motor blocks.

The electrolysis method is primarily best used for in-line rust removal. Another advantage is that after you have removed the rust and it has collected on the anode/cathode?, you can reverse the wires to the power supply and make freshly machined parts look antique and original. This was a huge advantage when restoring the hit and miss motors.

[Joe K]

Originally Posted by ursus

Joe K just explained why my phosphoric acid treatments have failed to prevent future rust breakouts. I am going to keep a pot of water on the boiler for the next episode of derusting parts. Thanks for telling us the rest of the story!

Well, thank you for the vote, but don't expect TOTAL satisfaction. You're still starting with an electrolytic surface that has been DESIGNED by nature to take on oxygen.

I have been known to do the electrolytic derusting game just to make it easier to get things apart. One story described on the 'net concerns sea chests that had been immersed for two centuries - were a congealed mass of iron oxide - and were able to be restored to functionality after electrolytic and disassembly/reassembly.

I think electrolytic techniques are currently being used on the recovered "Monitor" steamship which was recovered sunken off the east coast where it had gone down in a storm shortly after it's historical meeting with the Merrimack.

But (that "but" again!) I have also been known to do a "flash blast" simply to cut into that electrolytic surface a little and "disrupt" the little chemical anchor sites. Something about blasting and how it "disorders" the chemical bond sites - maybe by exposing new surface which has yet to develop a chemical bond attachment point?

I think the electrolytic part did the major de-rusting. The blast was superficial and just for good paint anchor - and relieved a lot of the abrasive wear and tear and hazard of blasting and distorting sheet metal body parts.

No one method is the solution for EVERY problem.

Joe K

[BILL WILLIAMSON]

JoeK, I noticed you used the wurd, "BUT"------Chief tole me that whin the wurd, "BUT" is used, you supposed to DISREGARD EVERYTHING thet wuz said PREVIOUSLY!! WELL, thet's whut he tole me & Chief DIDN'T lie, ever.
Bill W.

[Joe K]

That "but" is there to give me "wiggle room." I would hate to send someone away thinking I have the solution to flash rusting.

No. Better to send them away with a thought that I don't know EVERYTHING.

At least not yet. Still learning...

Give me time...

Joe K

[BILL WILLIAMSON]

"MAYBE" I'm a space alien & secrete something STRANGE?? I can hold a shiny, just "laundered" Zenith carb in my hand & watch it RUST, right in front of my EYES?????? I'm NOT kidding, I even showed it to the Dog! Bill W.

[Mad Mac]

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Originally Posted by RockHillWill

The biggest advantage that I can see from several years of using the molasses, was that I was able to accumulate a large collection of copperhead and rat snakes as well as two families of raccoons and several hoards of bees. It stunk after setting for a few weeks and was difficult to remove the residue from inside of cylinder heads and hit and miss motor blocks.

Ha! I guess we are lucky having no snakes or raccoons here in New Zealand. And being on a farm, smells are not an issue for me either. But I have to disagree with you about molasses being difficult to remove, as it dissolves very quickly and easily in water (its just a form of sugar). I use a water-blaster which easily removes the molasses and also the black residue that is left behind after treatment.

[Tinker]

Originally Posted by RockHillWill

The biggest advantage that I can see from several years of using the molasses, was that I was able to accumulate a large collection of copperhead and rat snakes as well as two families of raccoons and several hoards of bees. It stunk after setting for a few weeks and was difficult to remove the residue from inside of cylinder heads and hit and miss motor blocks.

I always wondered about the smell. We had half 50 gal hard molasses for the horses. You could smell it from a ways away. I guess if you used it and then dumped it youd curb the critter factor. I think ill just stick to ospho for rust conversion. But might want to try it out when the right project comes along.

[tbirdtbird]

BTW I NEVER wash off the phosphoric acid that I spray on (that is how I apply it). I DO wipe it off, and then let the sun dry it off, or use a MAPP torch lightly to dry the part. You are creating a layer of iron phosphate with this process. Iron phosphate is INERT and will not react to atmospheric oxygen (meaning it will not rust). Look at the Handbook of Metals from the 40s and you will see all this documented. Even a surface rusted part can be fixated against more rust by using phosphoric acid; it will turn the red surface rust to a black color, which is rust that has been converted and is no longer active steel/iron looking for an oxygen to bond to. This process is called 'passivation', look it up. All metal in my shop is treated this way, even if freshly blasted. It creates the best possible surface to bond paint to. We are doing this right now to an entire '31 slant body we just had blasted. I did my '31 Deluxe touring this way 20 yrs ago and the paint job looks brand new.

When you cut your teeth in the salt and rust-crazed northeast, you have to learn this stuff by heart else your paint jobs will only last a couple yrs.

I have a section of a Model A frame that I blasted and then treated with phosphoric acid 20 yrs ago and it still has that battleship gray color it did when I first applied the acid. There is no rust on it at all.

[28RPU]

I put a rear fender in molasses and left it for about a month. It was heavily pitted rusty to start with. When I took it out and cleaned it off it looked like new gray metal, even the pits were clean. It has been on my truck in the garage for over a year with nothing on it to protect it and its still rust free and clean. I swear by the molasses method. Its gentle and thorough. If you put a lid on it then the critters won't bother it and it won't smell. I use a 55 gallon steel drum and put the lid back on. I have an engine block soaking in one now.

[Joe K]

Prep & Etch Instructions

Directions for use
FOR RUSTED SURFACES
(To Remove Rust) 1. Remove any oil, grease, & dirt from surface. Remove loose rust with a wire brush. 2. Apply product to affected metal full strength with a paintbrush, spray bottle or pump-up sprayer. Rinse applicator with water after use. Work the solution into rusted areas and allow product to dry overnight to fully neutralize rust. 3. Rinse or wipe surface with a damp cloth to remove any rust residue. 4. Paint treated surface within 48 hours of application to prevent formation of new rust. Two applications may be necessary to treat severe rust.

FOR TREATING METAL FOR PAINTING
(Phosphotizing) 1. Remove any oil, grease, & dirt from surface. 2. Dilute 1 part product with 3 parts water in a plastic container. 3. Apply product with a paintbrush, spray bottle or pump-up sprayer to metal. 4. Thoroughly rinse with water after 15-30 minutes. 5. Paint treated surface within 48 hours of application to prevent formation of new rust.

We were both correct.

Still learning though.

Joe K

[tbirdtbird]

the rinsing step is not necessary for bare metal. I have never rinsed and have used the stuff for >25 yrs. If you are removing rust, use steel wool to work the acid into the pores and pits, and keep spraying on new acid while wiping the old off with a white rag or towel, until the rag no longer shows rust. Then spray on a final clean coat of acid, wipe excess, and sun dry or dry with propane or mapp torch. The heat of drying drives the acid into the pores. For this final step rinsing again is not needed. You can do it, but it is not necessary and in my opinion weakens what you have accomplished with the acid.

[Pete]

"There are chemicals (oxygen scavengers) that can reduce
the entrained oxygen further, but mostly these are not too
safe for home use (hydrazine - a commonly used chemical -
has been found to cause cancer in rats) These also
scavenge oxygen from your skin causing chemical burns."

Boy, does it ever. It was a common oxidizer used to mix
with nitroethane in the mid 50's for top fuel dragsters.
Today's uses include rocket fuel.

Basically what we have been talking about here with
phosphoric acid is the Parkerizing process. One of the
greatest rust preventive processes ever discovered.
The Parkerizing solution usually has zinc added to give the
finish a light gray color. It will have manganese added to
give the finish a very dark gray color or iron added to give a
dark black color.
The process is very simple. The part to be finished is
warmed (usually dipped in hot water) then dipped in the
190-210F solution till the bubbles cease. Then washed in
190-210F water.
This is basically what Tbird is doing in post #30.

[Mad Mac]

These two panels from a 1942 Chev truck show the result of soaking in molasses for 3 weeks at 6:1 strength (they are different panels but still show the before and after effect).

[BRENT in 10-uh-C]

Originally Posted by Mad Mac

These two panels from a 1942 Chev truck show the result of soaking in molasses for 3 weeks at 6:1 strength (they are different panels but still show the before and after effect).

Wow, I had to re-read your response in quotations because after looking at your pictures I was thinking the molasses actually repaired some of the rust-out areas!!

[Mad Mac]

Here is a better example of how well molasses works. Before treatment this 1942 Chev petrol tank was totally rusted. After 3 weeks in molasses the only rusted areas were those that I could not submerge because my molasses tank was too small.

[wrndln]

Mad Mac,
What type of molasses do you use - the thick liquid stuff mostly sold in smaller bottles or the solid dry molasses sold in livestock feed stores you mix with water.
Rusty Nelson

[28RPU]

Originally Posted by wrndln

Mad Mac,
What type of molasses do you use - the thick liquid stuff mostly sold in smaller bottles or the solid dry molasses sold in livestock feed stores you mix with water.
Rusty Nelson

I don't know about Mad Mac, but I buy the dried feed and mix it with water.

[Tom Wesenberg]

Originally Posted by 28RPU

I don't know about Mad Mac, but I buy the dried feed and mix it with water.

Same here.

[Mad Mac]

Here in New Zealand it can be bought as a thick gooey liquid for farm use (its fed to cows) and costs only US 17 cents a pound .

[Tom Wesenberg]

For derusting smaller parts a guy in our club bought a crock pot at a garage sale and uses pure white vinegar in it. He said it only takes 2 or 3 hours to derust the bolts.