I like the bubbling paint effect, very realistic.

Castle, 

Great job, very realistic!

Hey, did your little bundle of joy show up yet?

Looks great! I'd say you've got a pretty good handle on it.

Very well done so far, something I try to think about when I weather or try to rust something up , if it is greased or oiled unless it sets for a very long time in a corrosive environment ( high humidity or salt air)  corrosion will have a hard time taking hold. Idler wheels, return rollers, road wheels are all on bearings and packed with grease. The grease will ooze out over time and use causing a thin film. My train of thought just derailed. I still think your rust job looks great.

It's not bad--a little reddish, and maybe a bit random on the seat wall...you should add more patches and streaks. If there's rust anywhere, it usually means there's rust in a lot of places.

DOOG if you think about it ALL rust in photos here look a bit too red. i think it's a camera thing, even with dropping it into photoshop. 

CASTLE i have been working on a sand base using terrarium sand for a  1/35 T-72. while messing with it and the rocks i sometimes brush painted the sand which got messy but was an interesting texture. i wonder if that might be an option for some heavily eaten away areas. i too like the bubbling effect.

I'm hardly an expert but I like the results. 

Getlemen, thank you kindly for the feedback . The rust does look a bit reddish in the photo as noticed by Doog, in reality it is a bit darker. I will add more streaks and other rusty areas, when I am done changing diapers, catch a bit of a sleep and finished rocking the baby, shopping while Mrs C. is looking after the baby...this also answers hogfans's question .

Armornut, that is a good tip re. greasy areas. I will try to make this tractor look like it has been in service for a long time and not maintained well either.

Cheers...

Your welcome sir.

 You don't have to feed Beck for rust.
I like it, the second picture looks better.

 I think a bit of streaking and a different lighting angle
will improve your results and cure the redness of the picture without having to feed Beck.
 

 You're already changing diapers, trying to catch a bit of a
sleep and rocking the baby, even shopping while Mrs C. is
looking after the baby...

                            Beck won't starve.