Yes this is the risk with oil based weathering media, and why all weathering methods need practice (I use cheap train-set quality cars) before trying them out on valuable models.
It might be that chalks, of the desired color and shade of the car itself, might mask the effects of the oils but this itself is a technique that takes practice on perhaps scrap styrene before being attempted.
Dave Nelson
Maybe a thin wash of white over it.
Steve S
I use acrylic terra cotta when I weather (fade) boxcar red / oxide cars. I have not used it in a situation as yours, but that is what I would try. If it doesnt work, it's easy to get off. A pic would help in a better answer perhaps..
Tony
EK Sub in HO Scale
Hi,
I applied a wash of Oil base raw Sienna and thinner. appears too dark
on a box car red, I applied thinner to take off the thinner, but it
didn't work. Any suggestion how I can lighten up the wash? I
thought about using chalk.
Thanks,
Chris