hello all i was just wondering im building the tamiya m113 and i was wondering what colour to use for the wash im painting it in tamiya olive drab i know the usual colour for the wash would be black and brown but would this show up as the olive drab is allready a dark colour also would i use the paint straight from the pot or would it need to be darker or lighter it will be applied using a spray gun thx.

iF YOU ARE DOING THE M113 for the Vietnam era using some lighter earth colours will help u show up the washes. The olive drab could be faded in the centre of panels and big areas with a lil whitened OD and then use the standard procedure with black , brown, or even Vietnam reddish brown and it will show pretty well. The washes and weathering on my sidof view are not to be crying out from far so working step by step and adding washes you ll come to the point you want. And remember less can easily turn to more , but more is non easily reversed!!!!!

thx alot m8 sounds good to me also you say apply some reddish brown well i try to only use tamiya acrylics which colour do you think would match it.

Washes are usually used to show up detail. Using an air brush will tint everything the same colour and not help make detail more pronounced. Using washes like this can be called filters also. If you have a high contrast between your base colour and faded panel centres, filters are great to to tie them together. Pre or post shading with faded centres really adds to a vehicle ... gives a lot of depth and is the basis for most weathering.
Panel washes and pin washes around seems and detail is better made with a brush. Followed up with a little dry brushing, even the smallest detail is easily seen and can give great effects.

Filters and washes need to be thinned very heavily. Filters can be as much as 98% thinner and 2% paint. Its more like dirty thinner than thin paint. Washes around detail I would make slightly thicker. I use tamiya paints for airbrushing also, but dont like them for washes or brush work at all. It can be done but I dont think its easy. I much prefer oil or humbrol enamels for washes. Use both with humbrol enamel thinner as thinner. Great results and I think is much easier. Washes are usually darker to show up panel lines and details, but on some models ... dark especially, dusty lighter colours are very effective.
The red brown dust that major-gose talked about is more specific to vietnam. If your M113 is located elsewhere the dust can be sandy or earthy tones. I prefer to use ground up pastels for this. The chalk type used in schools, not oil crayon type. This represents the real thing better.
Hope this helps some!