If you happen to find some rusty old boules, don’t throw them away. They can be restored to playable condition. Here is a La Franc SB carbon-steel boule that I accidentally left outside in the summer heat and rain. It is covered in a thick coat of orange rust.
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This was not a disaster. A few minutes with a wire brush, and a few more minutes dragging the boule around on the ground to simulate a few days of play, and the boule was restored to playable condition. The boule on the left (see photo, below) is the restored boule. The boule on the right (from the same set) was kept out of the weather. The restored boule is darker in color and has a rougher surface (which I like), but otherwise the two boules are basically the same.
Click to view larger image. 
In this case, all I needed was a wire brush. If you have a boule for which that isn’t enough, then soak the boule in distilled white vinegar for a day or two. The acetic acid in the vinegar will soften the rust so that it can easily be scrubbed away. (If I’d used a vinegar soak first, I probably could have saved myself a lot of elbow grease with the wire brush.) Afterwards, remove the vinegar by thoroughly rinsing the boule with water, or with a weak solution of baking soda to neutralize the acetic acid.
A quicker solution is to use hydrochloric acid, which can easily be found (as muriatic acid) in stores that sell swimming-pool maintenance supplies. But I would recommend that only for extreme cases.
There are also products called rust converters that don’t remove rust, but chemically convert it to a hard, black, stable material called iron tannate. Rust converters are often used to restore and preserve iron-based historical artifacts such as old swords. For more information, Google (or search amazon.com or Youtube) for “rust converter“.
Note that it is also possible to use a short vinegar soak to blacken boules.
The moral of the story is that if you come across some rusty old boules, don’t write them off. They can be restored to playable condition. Depending on your taste, they may even be better than they were before they got rusty.
All About Petanque 
I have the same boules! Our terrain is by the sea and our climate is very humid and warm to hot all year. We play twice a week every week but only if we aren’t getting the rain this region is famous for. Suffice to say rust is a consideration.
I keep a Ziploc bag with a lightly oiled microfibre cloth in it. I give my boules a very quick wipe over with this cloth before stowing them away and especially if they got damp at any stage.
Did you know you can make your SB boules black again and very easily. A soak or wipe over with a very weak acid solution (vinegar, lemon juice, dilute hydrichloric acid etc) will change the outer molecular layers of your boule to magnetite (black colour). Quickly wipe with an oiled cloth afterwards to help seal in the colouring
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Hi kimbo (Kim Badcock, of the Mission Beach Petanque club in Australia), Thanks for the tip!
I bought a jug of white vinegar and left the other two boules to soak overnight. In the morning they were really black. When I washed them off, a lot of black came off on my hands. The boules were left with a deep uniform matte gunmetal grey color. There was a small shiny spot on the bottom, where they had been sitting on the bottom of the container. If I do this again, I’ll try sitting the boules on something porous like a bit of sponge or a wad of paper towel.
In this picture, the rusty boule is in front, and the two vinegar-blackened boules are at the back. The boule at the left has been played with more than the boule at the right, so it is more scratched-up.
Click to see larger image.
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I found a set of really rusty cloutee style at a vide Grenier recently. White vinegar removed heavy rust but left boules quite dark. Cheap tomato ketchup removed more. Imagine what I could have done if I’d used Heinz!
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Great! I googled around and discovered that the vinegar (acetic acid) in ketchup makes it an effective rust remover. A nailed boule will have lots of little crevices between the nails. Bob Vila’s web site suggests that after treating metal objects with acid (vinegar, ketchup, etc.) it is a good idea to rinse the objects in water and then immediately soak them for about 10 minutes in a mixture of ½ gallon fresh water and ½ cup baking soda. This will neutralize any remaining vinegar trapped inside the crevices. After about 10 minutes, rinse the items in warm water, and dry them.
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Hi, I am not sure if this is the right section to post but do you have any reviews (or come across any) on the OBUT MAINTENANCE PRODUCT ? Is it just normal WD-40 in a different container ? I am a bit concerned as one of our players is allergic to some chemicals in regular WD-40 and we have no idea what is in the Obut formula.
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Sorry, I have no idea what is in the Obut Maintenance product. But, frankly, I’m very skeptical about the need for any such specialized product. Boules are simply steel balls. The easiest way to clean them after play is soap and water and maybe a stiff brush (a toothbrush maybe) for caked-in mud. To protect them from rust in a very humid climate, I think Kim Badock’s idea (see the first comment) is easy and practical — “a Ziploc bag with a lightly oiled microfibre cloth in it. I give my boules a very quick wipe over with this cloth before stowing them away and especially if they got damp at any stage.” Any kind of light machine oil from your local hardware store should work fine. Another trick is to store them in a bag with some dry rice… the rice will absorb moisture in the air, helping to keep the boules dry and rust-free.
In addition, I think using a petroleum-based product at close range in a spray form is a bad idea. This is not the kind of product whose vapors you want to be regularly inhaling.
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Thank you for the alternative ideas and tips 🙂
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