Sludge washes for F-15E seat. Appologies in advance

make the sludge wash.

5 parts water
2 parts acrylic
3 parts detergent

apply liberally on your panel lines.
let dry.
use damp cotton buds or cloth and remover the excess sludge outside of the panel lines.
re-apply sludge wash to areas that need it (not enough color in the panel, etc).
again remove excess sludge.
re-do until satisfied.
done!

Ok I've just Futured the seat, and let it cure. I have artists acrylics in burnt and raw umber. What do I do next?

QUOTE: For an acrylic wash you can use artists water colour mixed with water and a few dropps dish washing liquid.This of course should only be applied over an ennamel gloss coat .

I use artist's acrylics for a wash over Future (another acrylic) exclusively.

You can you artists oil paints thinned with mineral spirirts but this should only be applyed over a cured( 48 hrs )acrylic gloss cote. For an acrylic wash you can use artists water colour mixed with water and a few dropps dish washing liquid.This of course should only be applied over an ennamel gloss coat .I find an acrylic wash is easier and more forgiving to use than an oil wash but i like the affects of an oil wash much better. Apply with a fine tip brush letting it run into recesses and around raised detail .When its dry you can clean up the excess with a lint free cloth or a wider paint brush using the appropriate thinner. It fairly simple really and a great way to pop out detail.

do you have to use acrylics?

Specifically what part don't you understand? Take a look at this page on my site:
http://www.craigcentral.com/models/wash.asp
It's for panel line washes, but the technique is pretty much the same.