Introducing "age" to a digital oil painting.

I have some interest in adding a yellowing from aged varnish and cracking as well to a future work. Has anyone ever tried this? What techniques can I use? Are there any programs I can use to supplement Rebelle in these processes? 

Agwal

to add yellowing i would experiment with the
Blend Modes of Layers

for the Craquelé i would experiment with Structures
or Stencils in Rebelle

Thank you for the reply. We'll see what I can do with this information.

Here my "crack" brush

I don t know if this will work here, I made this quick for my work even tho I have no idea how to really create brushes.

This should work like a stamp aka just use mouse on art and clik to apply the crack. Work best with "hard light" layer blending mode.

If you use pen and use it like a bush it will just smudge and create a black goo this is why I use it with mouse and just click where I want the crack.

 Sorry I just seen I uploaded my older version, this one work a little better.

I got a really nice set of 'crackle' brushes for my Photoshop app a very long time ago and use them quite a bit! I made a template of sheet of crackles, 12 x 12 x 300 size and use it with various lighting and shadows to make it look raised on this wall art I created.

Beautiful crackles!!

Thank you for the responses! I did not see this. Those are amazing.

Here another crack stamp.