[i:62c44e63cc]"assalaamu alaikum,
say somebody painted their walls with paintbrushes that had boar bristles would this make the wall najis? if people subsequently touch the wall with wet hand or lean on it with wet clothes does this make them unclean too?"[/i:62c44e63cc]

Boar bristle brushes are absolutely filthy. If the brush is dry then the filth does not transfer over however if they are wet then the filth does transfer over. Dipping the such a brush into paint make the paint impure. The impure paint would be spread over the wall making the wall impure.

Whilst the paint is wet, any material coming into contact would also become impure. When the paint dries then the impurity can not be transfered unless the paint becomes runny and wet which is not often the case.

I hope this answers your original query