Tamiya Acrylics are actually a Laquer based Acrylic, which is why many of use use Mr Color self leveling thinner.

Vallejo and others are water based, if using water to thin follow their instructions and use distilled water for great results.

Brush painting Tamiya Acrylics was a chore until I saw a advert for their retarder and boy that cured my brushing headaches.