How to make a rust backround image?

Question

I‘m trying to make a 1:1 rust/abstract background image in Photoshop. I have tried it, so far, with Filter > Render > clouds + different clouds + curves.

The picture below is an example:

Answer 1

"Paint it!" is a good option and it's already suggested by others.

Just in case you are not going to obey it here's some separate tricks to try with effects.

Your example has many colors which may need many layers. In the next image I have only one actual layer. The white background presents nothing, it's there only to make my brown layer visible. You replace the white with other layer or layers.

The solid color layer has got a layer mask. Filter render clouds is applied to the layer mask, the colors are, of course, black and white. The clouds appear as varying transparency of the color. Apply to the mask Curves. Tight tresholding curve makes sharp edges:

You may want smaller details. Noise helps generating them. Here's one way. Add some noise to the mask and apply to it Gaussian blur. A new tresholding generates small dots. Version A:

Version B:

Blurring the noise before tresholding makes the grains bigger. If you want large areas of dust-like texture at the edges of the solid areas, posterize the layer mask after blurring to 3...4 levels, but do it before adding noise. Treshold after adding noise. The next image uses it. It's taken from another attempt with different clouds:

Sometimes you may want apparent thickness. Layer style Bevel&Emboss makes it:

The thickness is removed. But the paint color itself has got some variety:

The "variety" is randomly selected filters: noise, artistic dry brush, contrast boost and sharpening.

And finally: Here's a version which has 2 layers eroded with cloud masks and other shown tricks. The background has only some embossed graininess.

There's no limit how much you can add by trial and error. The method is like gambling - it can succeed if one is able to stop at the right moment. Too many details make each other invisible. In the image above the blue has complex pattern, but it's nearly unnoticeable among the complex other textures. In the next image the same dull blue jumps up because the background (blurred clouds) is simple enough. The blurrines somehow forces the eyes to snap to the sharp details.

Check also old cases in GDSE. Some of them may have just what you want. Make a search for erosion, stain, rust, dust (just one term per search to get something).

Answer 2

What follows isn't a full tutorial, just the basic steps. I did this fairly roughly and quickly for demonstration purposes, but you can take more time and care.

Make a grunge brush or find one online. In the Bursh Settings, add some Shape Dynamics for angle and size jitter, Scattering, and Noise to randomize the brush.

Select two shades of brown for the foreground and background colour, and use Filter > Render > Clouds. You want something like this to use as your background layer. I sampled these colours from the original using the eyedropper tool.

On a new layer, with a lighter foreground colour such as blue, paint some random splodges with your new brush. (Again I sampled the colour) Use different sizes, add a layer mask, and use that to delete some areas, like holes, and apply the layer mask, then apply the Unsharp mask filter to solidify it.

Repeat for other colours of paint until you have as many layers as you want.

Go find a nice grunge texture on the web, or take a photo of one yourself. And set add it as a layer on top of all the others, desaturate it, and set the blending mode to Darker Color.