I am not sure if this is the right place for my post but anyway....

I have a mk3 fiesta with original rs running boards and arches (made from plastic) a fibre escort cosworth front bumper and a fibre rear bumper (not sure what it s called). My problem is that the arches are coming off they had some sort of black sealer to hold them to the body that is coming ondone. I know they have rivets or screws and they won t fall off but they look scruffy like this and i want to fix them

What is that sealer called? or is just normal metal black sealer?

Also is it instant dry? or you need to fix the arch to the body with masking tape or something?