<VV> Derusting---Was "I was wrong..." Long

[J R Read_HML]

What the heck is Washing Soda - do you mean laundry detergent?

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Later, JR

----- Original Message ----- 
From: "WadeHalsey" <HiHal at adelphia.net>
To: <virtualvairs at corvair.org>
Sent: Saturday, May 14, 2005 5:53 PM
Subject: <VV> Derusting---Was "I was wrong..." Long


>
>>also, you can use normal table salt, but water
>>softening or sidewalk salt does MUCH better....and
>>it's cheaper too.
>>
> I have never heard of using table salt in any derusting solution! My notes 
> on the topic gathered over the years suggest using common WASHING SODA 
> instead. Following are my notes on the topic from this and other 
> forums-----Wade Halsey
>
>
> "Anyone restoring a rusty old car should learn about this type of rust 
> removal. It uses chemistry to make work easier. You will need a large 
> container to hold the solution, a battery charger such as a 10 amp, 
> sacrificial piece of steel, such as a section of stainless sink because 
> stainless lasts longer. Or use an old stainless pot or pot lid. You want a 
> piece of steel with a lot of surface area. Then some washing soda from the 
> grocery store.
> Fill the container with water and add one tablespoon of washing soda per 
> gallon of water, more soda is OK. Put the steel in the water and put the 
> red or positive (this is important) clip from the charger on the stainless 
> steel. Keep the clip out of the water since it is made of copper and will 
> disintegrate fast. Take the rusty part and put it in the mix and attach 
> the negative clip to it. If the clip goes in the water it's OK. Plug in 
> the charger and wait. Don't let the part and the stainless steel touch. 
> You will see bubbles start to come off the part within minutes. If you see 
> little bubbles it's working. Give most parts a day and they come out with 
> no rust. This process turns the rust into a black substance that you can 
> wash off with a stainless steel wire brush and a scrub pad. Wear gloves 
> while cleaning or the black stuff will stain you fingers. The rustier the 
> part the longer it needs to soak. This process will remove paint and all 
> the rust and will not damage the good metal. It is much gentler on the 
> metal then a wire brush on a drill and is a lot easier. When the solution 
> gets dirty dump it on your lawn. The grass likes the iron and gets real 
> green.
> The rust removal system works great. A note of caution. The bubbles coming 
> off the positive and negative electrodes in the solution are Oxygen and 
> Hydrogen. They aren't poisonous to breath but the Hydrogen gas is 
> extremely flammable. Do this process in a well ventilated area. Air it out 
> before you do any gas torch or arc welding operations.
> One problem is that once you clean the part with water and a scrub brush 
> you will need to dry it and be ready to paint it with a primer or it will 
> flash rust. Remember, you can leave it in the solution till you're ready 
> to clean it. This process will not hurt good metal only rust. I took a 
> rusty rim for three days and it looks new.  Jerry Mannix White 56 -
>
> Question: How does this solution affect other materials like rubber 
> bushings or plastic parts. In other words, do steel parts to be de-rusted 
> have to be completely stripped down? And one last question, what about 
> embrittlement of parts like springs? Is this method safe to use on 
> suspension parts etc?
> It doesn't.  This is basically (really there is a lot of other stuff going 
> on also, as it is a double compound replacement reaction) an 
> electro-chemical process that changes the ferric oxide (Fe2O3, scaly red 
> rust,) to ferrous oxide (FeO, black hard rust).  The solution sodium 
> carbonate and water is a buffered basic solution with a PH of  10.  So, if 
> an alkali (basic) mixture won't hurt it, it is ok.  It does not affect the 
> strength or hardness of the steel or iron, beyond that already done by the 
> original rust.  You are simply coating the part.  Anodizing aluminum is a 
> similar process although it is done through a chemically different 
> process.  Aluminum or any other reactive metal in this bath, will pit 
> extremely fast. Jim Davis
> You can use any steel but stainless steel lasts longer. Normal steel like 
> a cookie sheet will last about a month and corrode away. Get an old 
> stainless kitchen pot at a yard sale.  Don't use baking soda, WASHING SODA 
> makes a much better solution. Baking soda works but will slow the process 
> and you need to keep adding it to the solution you have. The purpose of 
> the washing soda is to create an electrolyte solution, washing soda is a 
> better conductor. It also costs less then baking soda. You won't hurt 
> anything by using baking soda but you may have a higher electric bill due 
> to the fact it will take longer to de-rust each part. With either solution 
> you use you have to change it or add more soda every few weeks to keep it 
> working ant top efficiency.
>
> I found this technique (sodium carbonate and electrolytic reduction) on 
> the antique stationary engine mailing list.  I was intrigued, but also 
> distrustful.  Surely it was corrosive, hazardous, or something similar. 
> All the chemical derusting techniques I had seen involved acids and 
> corrosion of good metal.  The stories thrown around suggested that this
> was not so with the washing soda method.
> I searched and found that museum conservators with irreplaceable ferrous 
> artifacts prefer this method precisely BECAUSE it does not allow any 
> corrosion of intact metal.  If done with Sodium Hydroxide (lye) instead of 
> with Sodium carbonate, it's actually capable of converting iron oxide back 
> into metallic iron.  (NOTE:  I DO NOT
> RECOMMEND USING LYE FOR THIS PURPOSE.  Its advantage over washing soda is 
> largely theoretical and it is vastly more DANGEROUS) For that matter, the 
> process does not remove the corrosion products; they are instead
> electrolytically reduced from rust to black magnetite, but they stay right 
> there on the metal until you rub them off with a stiff toothbrush or 
> something similar.
>
> The solution will have no effect on rubber, but may roughen the surfaces 
> of some plastics.
> Remember that the reaction is done in a reducing bath with an alkaline 
> electrolyte.  Hydrogen embrittlement is
> from exposure to acids.  (free hydrogen radicals attacking metal) 
> Admittedly, the electrochemistry alters the case somewhat, but emperically 
> I'd be willing to argue against measurable ion migration out of the metal 
> itself over the amount of time that derusting is performed.
> The areas to be derusted need to be free of anything that would inhibit 
> the solution making intimate contact with the
> metal itself.  Free flow of electrolyte past the surfaces is important in 
> maintaining a constant field strength and solution concentration over the 
> surface being treated.  Greasy metal is a bad idea. So is a significant 
> covering by anything else, although I've seen it do a fine job in removing 
> paint after immersion for a week or so.
> One other huge win of this process over any other rust removal procedure 
> I've found is that it reverses the swelling that binds rusty parts 
> together. The problem is caused by the simple fact is that rust is bigger 
> than the iron from which it came.  Accordingly, a rusty bolt swells in the 
> rusty hole in which it is threaded and no longer unscrews easily.
> The electrolytic reduction process turns the rust into magnetite, which is 
> both mechanically weaker and smaller than rust.  Usually you can unscrew 
> parts that have rusted together if they're carefully treated in the bath 
> for a while.  My test case for this was a pair of otherwise-good 140 HP 
> exhaust manifolds which had bolts screwed (and rusted) into the 
> drilled-out stud holes.  After cooking for about a week the bolts 
> unscrewed with moderate effort. Rad Davis
> Jim Davis wrote: Rad got me started with this a couple years ago.  It 
> works as  advertised.  Be patient a really rusty part will take 24 to 30 
> hours to  completely harden. For those young ones who have never hear of 
> washing  soda; it is sodium carbonate.  It that chemical we use in 
> swimming pools  to raise the PH. Jim Davis"
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