primer over old paint?

[joysday]

I am scraping and repainting an old deck. I can only scrape off about 70% of the old paint. What's left is in small irregular streaks here and there. Is it okay to put the primer right over this old paint since I can't possibly paint around it -- I guess the other option would be to use a paint remover? Any advice welcome!
Joy

[marksr]

Unless the paint is chaulky there is no need to prime it, but it won't hurt anything. Remember the better the prep and quality of material the longer the paint job is apt to last. :)