I've had a few people ask me how I achieved this rusted effect for my book cover. Unfortunately, I didn't take photos while I was doing. Fortunately, there are several ways to get a similar effect and other people have made videos.
You could probably achieve this look with water-based products, but the steps would be different. The techniques here are based around acrylic paints.
I'll write down the exact steps I took and products I used, but you can get to a similar look if you have:
a dark surface--for instance, black cardstock or paper covered with black gesso or black paint
Yellowy Green OR Teal paint
Orange, Yellow, and Brown Paint OR reddish-brown and yellow paint
Optional: Something to add pebbly texture and something to add glimmer or sheen
Optional: Ephemera and embellishments, such as chipboard, resin, stickers, etc.
Links to various method tutorials:
Cheap & Easy
Dave Lowe Design Faux Rust Painting -Quick, Easy and Cheap video
Creating Faux Rust ~ DIY with Iron paint and cinnamon
More complicated, but cooler
Terri Sproul's Rusty Metal Technique video
Shoshiplatypus Rust Effect video
Stillman & Birn Zeta Sketchbook Hardbound (5.5x8.5in/14.0x21.6 cm)
UmWow Chipboard: Layered Squares, Layered Clouds
Golden Fluid Acrylics:
Iridescent Micaceous Iron Oxide
Quinacridone Burnt Orange
Hansa Yellow medium
Golden Coarse Pumice Gel
Polymer Medium gloss
Paper clock cut-out
Pattern paper flower with resin center
I used make-up sponges to apply the paint and a palette knife to apply the coarse pumice gel.
My Stillman&Birn sketchbook has a black cover, but a hatched texture so I primed it with clear gesso.
Once that dried I painted the cover with Micaceous Iron Oxide. I like it because it has some tooth, and also a metallic glitter.
Once the Oxide paint was dry, I painted on the teal. The teal is pretty opaque, so I left small areas bare, and spread it thinly in other areas. This I also let dry.
I used Polymer gel to glue down the chipboard, flower, and resin embellishments, and then spread Coarse Pumice gel at random. I layered it around and partially over the embellishments, and let it set for a couple of hours.
For the last step, I sponged on quite a bit of Quinacridone Burnt Orange, and small areas of Hansa Yellow medium (which I worked into the Quin Burnt Orange). I left lots of the teal and some of the Micaceous Oxide showing.
For the back, I repeated these steps, except that I didn't add any embellishments or coarse pumice gel. (The back isn't quite done. I ran out of Quin Burnt Orange.)
I also repeated the process on a two-page spread in the book, sans embellishments or coarse pumice gel.
So that's it! Have fun rusting your bright and shiny new stuff, lol!