Banana and jarndice: my experience with acrylics showed me that once dried, an acrylic is impervious to even its own brand-specific thinner. Maybe I am wrong about that. Here in the 'States, I (and some other modelers I see weekly) get a strong detergent called "Super Clean": so far it has stripped enamel or acrylic paint off plastic without harm. SINCERE DISCLAIMER: I am not making any guarantees as to the effectiveness or harmlessness of Super Clean; just my experience has been so. I first bought Super Clean via Amazon and paid w-a-a-y to much for it. Now I find it at "big box" stores (Home Depot, Menard's, Lowes are names here in the 'States) and even (flinch) Walmart.