 Fluid writer has a reservoir to put a liquid into and a nib or a tip for writing or drawing. If your ink or paint dries inside, use some soapy water and a toothbrush into both ends. The bristles will get down inside there and clean it out. You may need to soak it in there a little bit first. Then you can replace it with whatever kind of ink or paint or masking fluid that you want. But my recommendation is don't let anything dry in there and then you won't have to deal with fussy cleaning to get it to work again.