Hi Gang,
A friend once told me of a way to mix Windsor and Newton ink with washing up liquid and water to produce a shading effect on vehicles and uniforms,now, like an idiot i`ve forgotten what it was !.
I recently tried to do it again on a kit but only succeeded in turning the whole thing black !!.
Can anyone out there put me out of my misery by telling me what the ratio should be ?

While probably I cannot tell you the exact ratio, I presume the whole mix should be very-very thin, more like a sligthly tinted thinner than thinned paint. It is a good rule of thumb to keep washes very light and thin every time, since it is much easier to apply a second coat than removing any previous one.

c[ ]

Winsor & Newton ink? Really? It contains shellac and it's not light-fast - I'm not sure I'd trust it on a model, much though I love it.

Shellac is thinned with denatured alcohol. NOT WATER, so I wouldn't use water to thin it.

Winsor & Newton recommend thinning with distilled water. I use tap water and it's fine. But I only use it on paper, not models!