Improvising Tips and Tricks

[Fox]

Sorry if this is a bit of a necro but it's a handy weathering technique:

Give the entire model a metallic basecoat and wait for it to dry.
On areas you're going to apply weathering, spray/paint a light application of an inbetween color between the metallic basecoat and the final color (about a 50/50 mix). wait to dry
Apply sand mixed with elmer's glue to areas where you want to be weathered.
Spray the desired model color over the sanded model.
it
Once dry, simply flake off the sanded areas. This creates the appearance of battle damage/paint flaking/etc. exposing the primer layer and the initial top coat of the model. While this technique is generally used for car and tank models, it winds up looking quite nice on mecha.

I've heard of a similar weathering method, using grains of salt instead of sand. It's used more for rust effects and discolored metal.

Back in the day I just dab in some gray acrylics for the peeling paint

It's what i do even until now. I'm too much of a chicken to even try any other techniques.