What is the safest way to keep ants away from hummingbird feeders?

https://www.pestremovalguide.com/10-easy-ways-to-keep-ants-out-of-hummingbird-feeder/

I've tried two things that seem to work. One is to spread a thick patch of Vaseline on the shepherd's hook (if that is what you are using). Make it a thick layer and I spread it out about an inch. It lasts for quite awhile, even in full sun. The other which I had some success with is double sided tape. You have to change it often though, as the adhesive doesn't seem to last as long when in the sun.

i have my feeder hung with a shepherd's hook and i don't have any ants. not sure if the hook is the reason or not.

The safest and cheapest way is to use chalk. Ordinary white chalk. Ants will not cross over chalk lines.