Floor to ceiling book case

[Jupiter01]

Thought it may be helpful to post some pictures of the type of gaps I want to fill.

 

[Jupiter01]

Can I have some advice on whether I should prime first or fill/caulk?
Also, do I rough the surface up with some sandpaper before I prime?

Thanks for your advice

 

[Deleted member 174758]

MDF certainly needs to be sealed before finishing. End grain (I.e exposed cut edges) will need more coats of primer than flat surfaces. Denib between coats of primer with something like maroon Scotchbrite (Scotchbrite like materials available from Machine Mart and some DIY stores). It is generally better to work up through the grits of sandpaper before priming, to at least P320 if you want a smooth finish. Vacuum you or wipe off areas with a tack cloth or lint free rag dampened with white spirits or the like between grades of paper for better results

 

[Jupiter01]

UPDATE: finished up this evening and really happy with the results. I’ve had so much help from all of you and once again, really appreciate it.

Wanted to share some pics from the project.

 

[Deleted member 174758]

A job to be proud of. Well done!

 

[Jupiter01]

You in particular, have helped me immensely @JobAndKnock