Garden Elements are untreated iron and if left untreated, they will form surface rust.
Painted Finish DIY
You may paint or clear coat your purchase with an exterior grade metal product to help prevent rust. Clean your iron with mineral spirits or paint thinner first for the best paint adherence. Follow the manufacturer's directions for a great finished product.
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Rusted Finish DIY
To speed up the rusting process, you can lightly sand the steel and/or apply a mixture of 4 parts hydrogen peroxide, 1 part vinegar and a pinch of salt. Allow it to sit for up to an hour and gently wipe. Repeat the process until your desired result is achieved. For garden elements, the finial will rust more quickly than the steel bar when exposed to the elements and doesn't require any treatment.
There are other ways to encourage rusting. We suggest a google or YouTube search if you're really interested in rusting your purchase.