Letter 38050

I need to rust spring steel on purpose  

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I work for a marking and identification company. I need to rust pieces of finished spring steel. We make printing dies to imprint on sparkplugs. We adhere a neoprene rubber die with glue to pieces of spring steel and have found over the years that rusting the steel first allows for a stronger, longer lasting bond. Our current method for rusting the spring steel takes approximately 3 weeks, and we really need to speed up the process, if possible, to a week or less. Currently we soak the steel pieces in water and liquid dish soap, changing the water every couple of days, for 2 weeks to remove the oil on the steel. Then we lay out the steel on newsprint and spray with water until we get the acceptable amount of rust, approximately 1 week. Any help would be greatly appreciated.

Pete Lamoureux
Marking and Identification specialists - Farmington Hills, MI, USA

I'm not sure that if you accelerated the process that the surface would exhibit the same adhesion that you achieve from your present process. But steel can be "rusted" nearly instantly by a process called black oxiding. My understanding, though, is that brass plating is the best treatment of steel to get rubber to adhere.

 
Ted Mooney, P.E.
finishing.com Inc. - Brick, NJ

My guess is that you need the surface roughness for the adhesion.
An alternative might be to soap and hot water clean,rinse, clean with eazy off oven cleaner, rinse and dry.
Abrasive blast (lightly) with 400 grit aluminum oxide, wash and dry.
You can get spot blaster for a few dollars now If you have an air compressor) which would work quite well.

James Watts
- FL

Try to use bleach and vinegar mixed together. (In a well ventilated area) Apply with an old paintbrush or spray bottle or just dip the steel in it. This will oxidize steel in a flash... Good luck

Craig Gilbreath
- Waco, TX, USA

Let's emphasize that "well ventilated" again, Craig . . . as in maybe only do it outdoors and upwind on a very windy day?

The reason the mixture oxidizes steel in a flash is that the vinegar, being an acid, neutralizes the caustic soda in the bleach which was holding the chlorine gas in solution, so that it can no longer hold it. The result of the mixing is a release of copious volumes of highly oxidizing, toxic, poisonous chlorine gas from the bleach. This is precisely what those warning labels on the bleach warn you not to do :-)

Ted Mooney, P.E.  finishing.com Brick, New Jersey

Have you tried dipping it into normal car battery acid. After dipping, just leave it exposed to the elements. Will be well rusted within about 3 days.

Charl Marais
- Johannesburg. South Africa

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