can you use it just for/replacing tips, or do they only work over the full nail?

if so, which is best? the powder or the tips?

Not quite sure what you're asking, but coloured powder can be used anywhere on the nail you like, you can design alsorts with coloured powder.
Or are you talking about just the white powder? I use my white powder on the free edge, I don't used white tips, but I also usedthe white for 3d designs. HTH

sorry if i wasnt clear enough. i was asking if you can use coloured not white powder, if being careful to apply just on the tip, to create a coloured tip, whereas put clear (for eg) powder on the rest of the nail, hence colour french tip. i hope that makes sense to everyone

Yes I use Ez Flow powders for this . You can sculpt it like white powder. x

thank you Judy for your help. another question which do you prefer to use? powders or normal glue on tips?

Totally depends on whether you like sculpting or prefer to use tips. Have you seen Geegs Ruby Slippers turorial? If not here's the link, brilliant step by step.
http://www.thenailgeek.com/nail-art-...step-step.html.

HTH

Uh i see