This from the Ritter-Easley list:

From: "Ray & Leigh"
To:
Sent: Monday, August 25, 2003 8:20 PM
Subject: [MB] de-rust


I have been following a discussion on the welding list (Hobart) that the following process is used to de-rust pieces.

Use a plastic container appropriately sized to the rusty piece; fill with> water and add 1 Tblspn of Arm & Hammer washing powder (calcium carbonate?) per gallon of water. Using a battery charger attach an old mower blade or carbon sheet to the anode (neg) and place in the solution while attaching the cathode (red) to the rusty piece. Let site over night or 4 hours: No more rust.

PS - Instead of POR-15 they suggest phosphoric acid.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

hmmmm.i wonde if i could find a bucket large enough to hold my 1980 300sd.there is a hydro substation nearby

"PS - Instead of POR-15 they suggest phosphoric acid"

The 3 part process for using POR15 has you use the Metal ready as the second step. Metal ready IS phosphoric acid

Dave

__________________
1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car

Phosphoric acid is commonly sold as "Naval Jelly."

Remember, this technique sounds like it's for bare metal that won't be painted. Arm + Hammer washing powder is probably baking soda, sodium bicarbonate. It's a base which is noncorrosive to metal and would neutralize acids. But the best rust preventions are still those that involve covering the metal so oxygen cannot attack the Fe and turn it into Fe2O3 (or other formulas depending upon the oxidation state of the steel originally). In other words, primer and paint! Cover any/all bare exterior metal!

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

Washing soda is sodium carbonate (baking soda is sodium BIcarbonate. Both are mild (realitively) bases. Good for neutralizing acids like battery acid (sulphuric).

__________________
Bill Streep
San Antonio
'57 190SL (toy)
'08 S5500 (mine)
'09 CLK550 (wife's)
'06 SLK350 (daughter's)
'11 GLK350 (daughter's)
'03 CLK310 (spare)

Electrolytic "re-rusting" has been around for a long time, the use I'm familiar with is removing rust and corrosion from old woodworking tools.

Won't restore the surface texture, however, it will still be pitted and rough, but it will be all iron, not rust.

Wash the carbonate electrolyte off at once, though -- when the current is removed, it will PROMOTE corrosion!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Baking soda? Hell, best anti acid on the market. After the tacos, Just a small teaspoon in a glass of water and no more acid. Beats tums, rollaids and other over the counter acid nuturalizers. Good for cleaning metals also, and teeth and . . .