Our ITLA Scale Model components can be easily brush painted with water based acrylics and still retain their laser etched details. The secret is to use as little paint as possible to colour the part... almost using a "dry brush" technique to apply the opaque base coat.
In the examples pictured, we used simple craft store water based acrylics... a grey and a silver to provide the initial colour on each part.
After the base coat is dry, we again use brushed on water based acrylics to add additional layers of weathering colour. As shown below we created a couple "washes" using raw umber and orange to represent rust in various shades to age the ductwork.
That's it, and it only took about 5 minutes! These techniques are very simple to use... give it a try and use your imagination or prototype photos to add a variety of colours.