Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Did I Remove Enough Rust?
Q. I have recently purchased a wrought iron console which needs a little rust removal and repainting. I sanded, cleaned with a wire brush, a tack cloth ⇦[this on eBay or Amazon affil links] , soap and water. While there is no flaking paint or raised rust anymore, the rust colored spots remain.
Should the piece be without any rust color on it at all? Is this even possible? If so, sanding just isn't going to do it because I sanded hard for hours and did remove a tremendous amount of rust and totally smoothed the finish of the piece..Once I get the answer to the rust problem, do I need to prime the piece before painting? What is the authentic color of old wrought iron? Was it flat black, or more of an iron/grey/black color?
Sandi S [last name deleted for privacy by Editor]- Raleigh, North Carolina
2001
A. One way of removing oxidation would be to dip the piece in an acid solution. However, following this step you must not allow the piece to be exposed to air prior to finishing. Blackening can be accomplished by purchasing a blackening compound for steel traps at a sporting goods store. An old-fashioned way of accomplishing this is to boil the red tips of the sumac tree and immerse the piece in liquid while it is boiling. I used this process to blacken traps when I was younger and it worked well and inhibited rust formation.
Brian DeBadts- Rochester, New York
2001
A. Remove the remainder of the rust with a commercial rust remover like naval jelly.
Rinse well and allow to dry thoroughly. Paint with Rustoleum or similar material. These contain chemicals that inhibit further oxidation.
- Utica, New York
2001
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Ed. note: see letters 26857, 32772, and 33964 for additional discussions on this topic.
Q. I want to refinish my mother's outdoor wrought iron table and chair set. It is rusty and flaking. What is my first step? What kind of paint do I use? What is the difference in finishes between powder paint and spray?
Thank you for any help.
Jennifer D . [last name deleted for privacy by Editor]- New York City, New York
2001
Q. I have recently rescued a set of 4 wrought iron chairs and wrought iron & glass table from a scrap heap. The finish is a sage colored verdegris. I would like to paint it a different color but am unsure about the best way to prepare it for painting.
Any suggestions regarding what to do as well as what not to do would be most appreciated.
Karen L [last name deleted for privacy by Editor]- Columbus, Ohio
Q. I would like to paint an interior black wrought iron railing with an ivory color. Are there certain paints that work better for this than others? oil or latex ok? Are there any special prep techniques I need to use?
Thanks,
Tom F . [last name deleted for privacy by Editor]- Apple Valley, Minnesota, USA
Q. De-rusting canal boat. I need to remove/convert rust on a narrowboat I am painting. The boat is new so only surface rust is present. can you please confirm what is the best product I should use (e.g., acids) and in what form. thanks for your help - Mike
Michael John Lewinhobbyist - Peterborough, UK
2006
Q. I am attempting to refinish a very rusted iron bookcase.
Bookcase is constructed of 1/4" round iron "bars" separated approximately 2". as this is my first project of this type any/all help would be appreciated ... especially in the stripping phase.
- houston, texas
August 23, 2008
A. Hi, Michael. I'd start by sanding away the heavier and looser rust and then, as mentioned by George B., naval jelly ⇦this on eBay or Amazon [affil links] is a good starting point as it will convert the powdery red rust to adherent black rust. Then you can simply use Rustoleum or Krylon paint for metal. Good luck.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
August , 2008
Q. I have 76 steel brackets for shelving I plan to erect. The brackets are rusty so I have soaked them for a few weeks in three parts water to one part vinegar ⇦in bulk on eBay or Amazon [affil links] , and then in pure vinegar for a few days but the brackets discolored soon after taking them out. Two brackets that I took from the water/vinegar solution were placed in motor oil for a few days and they have not discolored weeks after the treatment. Would the oil treatment affect their being painted? When you etch metal with vinegar do you immediately cover it with Rustoleum primer and paint or do you first neutralize the surface with baking soda and water before painting it? I need to know how to proceed since I have many rusty materials and tools to restore. Thank you for your assistance.
Daniel Alarcon- Plant City, Florida, USA
July 2, 2015
A. Hi Daniel. Rust is a reaction of steel with water or moist air, so oil will prevent it, but oily things can't be painted. So you should oil tools and similar things which don't get painted, but don't oil your brackets.
The ideal pretreatment before either painting or oiling is phosphatizing, and naval jelly ⇦this on eBay or Amazon [affil links] is the consumer's approximation of phosphatization. vinegar may or may not have been needed, but at this point I would take the brackets out of the vinegar, quickly rinse them, and quickly treat them with the naval jelly. Then you can paint them. Next time try the naval jelly without the vinegar. Good luck.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
July 2015
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