Pinterest 'Pin It' hover for CERTAIN IMAGES ONLY

Hi
As per the topic title, I want to be able to add a Pinterest ‘Pin It’ button on hover to specific post images only.
I know there are lots of plugins which add the Pinterest button to every single image, and that some of them have a shortcode which allows you to hide it on chosen images if desired, though I would prefer to add the hover myself to specific images only, rather than have to remember to take it away each time I write a post.
Any advice greatly appreciated.
Thanks.