Outcome:

 

1. To start:

 

Get your canvas:

 

 

2: Go to filter>render>clouds>difference clouds, I used defaults, but you can mix it up if you want.

 

Should have something like this:

 

 

3. Now get your brush. (I used Galaxy - Big, a default gimp one. You may use a different one or your grunge brushes.)

 

Start smudging it, should get:

 

 

4. Get a new layer, make it black:

 

 

5. Then make a big supernova in your focal point. Filters> Light and shadow > supernova.

 

Maybe something like this?

 

 

6. Smudge your supernova layer a bit, like this:

 

 

7. Set on overlay. Duplicate a few times till it looks good.

 

8. Now go Edit>CopyVisible, then paste.

 

9. With your new layer, go to Filters>Distort>Video. Click ok.

 

You'll get this:

 

 

10. Set this layer to overlay

 

11. Now, with you brush erase little bits of your lines on that layer. Like so:

 

 

12: Now smudge around those parts so you get something like this.

 

 

13. Make a new layer (transparent) and with your vine brush outline your grunge focal bit:

 

 

14. You might think, what the hell am I doing. Now, check your brushes menu, that its on the vine brush. And there will be a little slidey thing with spacing next to it, pull it right to the left, all the way to one, now start smudging.

 

15. Should have like this:

 

 

16. Now go to Filters>Enhance>Sharpen and put it between 80-90 should have this.

 

 

16. Now, set this to overlay. Then get the vine layer, and go to color>colorize. Select your hue. That will be your base colour. Im using b&w though.

 

17.

 

18. If your light points are too big, go to your smudged supernova layers, and smudge into the centre of the supernova's direction.

 

 

 

I know my first outcome and second outcome are different caus I lost my tutorial for that one on top.

Nice smudged background. But I wouldn't call it a grunge though. ;)

This doesn't seem to be grunge, but nonetheless good sig tut.

It's close to grunge, but the smudging makes it more of a smudge sig. It's a good tutorial for a good background though :thumbup:

Quite a nice tutorial, I'm sure it will help some beginners out. It's a grunge-ish background I'd say, but I imagine you could make it look more like a real grunge background by smudging with different brushes.