Fill this document with neutral gray.

For that, go under the edit menu > fill

Then, add a monochromatic gaussian noise with an amount of 45.

Apply now a motion blur to get a brushed metal effect.

Keep the parameters you can see now on the screen capture.

We can notice a small default on the right and left edges of the plaque.

You will remove it by using the Crop tool (or press [C])

Use it like on the screen capture.

Double click in the selection or press on [enter] to apply.

We are close to the final brushed metal plaque, but it is not enough convincing. So we are gonna accentuate the brush traces.

For that, go under the Edit menu > curves or [ctrl + m]

We have created a metal plaque.

It is too regular ... isn't-it ?

Yeah it is :)

So you are about to age it:)

Create a new calque by clicking here, bah name it " clouds ". Tape [D] to re-initialize the foreground and background colors, then apply the Clouds filter under Render > Clouds. Change the property of the "clouds" layer like on the screen capture (Overlay mode)

Don't you think this metal is missing some highlights ?

No problem ! :)

Now you will use the sharpen tool and apply on different areas of the plaque, just like you can see on the screen capture.

Note : Here, I used a brush with a hardness of 0%

Now we are going to give it a hue orange (hmmm our plaque starts to rust ! :) )

For that, select the "clouds" layer then create an adjustment's layer by clicking on + [ctrl]. Then, select Hue/Saturation type.

Click OK ! :)

Set up the parameters like on the screen capture. If you don't like the Hue, Saturation or Lightness parameters, bahh change them :) . You are free to do it ! :)

Now you are happy, you have rusted it :)

You can make this hue a non-regular one by drawing of this layer with the pencil. The black areas of this layer are ignored while the white ones won't be ignored.

A la fin de cette étape vous devriez avoir un résultat semblable à celui-ci.

Good ! :) Now the art of rust is to manipulate the Dodge and Burn tools (O et shift + O).

Set up the Burn tool with the parameters of the screen capture (to get the options, double-click on the tool) :

- Exposure : 50%
- Tone : highlights

Set up the Dodge tool like this  :

- Exposure : 50%
- Tone : shadows

Save your image under another name (like rouille_v2.psd)

Flatten your image in your layer menu > flatten) or [ctrl + shift + e]

Then paint on the background layer with a brush of very low hardness so as to obtain a result similar to this one. For the central parts, you can use an opacity lower than 50%.

My advice : use the Dodge tool on the edges of the areas where you used the Burn tool so the transition will be more realistic.

Don't forget that a rusted metal plaque has lived, so it is scratched.

To scratch it, you will use the same tools and the tone mode will be midtones.:)

Now be creative! :)

Good, we are gonna make older paint traces :)

Create a new layer and fill it with black ([d] puis [ALT + Suppr]). Then, with the paintbrush tool, paint in white in random.

Duplicate it now 2 times, by sliding it on this icone .

Select the first copy, then apply the ocean ripple filter : filter > distort > ocean ripple).

Select now the second copy et apply again the ocean ripple filter. Keep these parameters ([ctrl + f]).

On the second copy, apply it 2 times.

We don't want the black areas on those 3 layers, let's get rid of it :

Go under the Select Menu > Color Range, Set it up just like on the screen capture, then click on the black part of the image. It will become white in the preview.

Click Ok, then hit [backspace] on your keyboard. The black is gone ! :) Then press[ctrl + d] to deselect.

Proceed the same with the 3 layers. Be sure to have only one layer active and visible each time you proceed. To do that, uncheck the eye icon on the other layers.

Now change the 3 layers mode into overlay. Opacity of the first layer must be 50%, the first copy : 25% and the second copy : 12%

Click on the background layer and apply a non-monochromatic gaussian blur of 5.

And you should get a result similar to this.