Putty problem.

Hello fellow modelers.

I have a problem with a project that I'm currently doing. I'm using Mr. White Putty to fill in panel lines. I sanded it down and it looks perfect, but after awhile the panel lines started to show again. How long do I have to leave the putty on before sanding it down? Is there a better way to fill in panel lines? Feedback please!

Cheers!

Some types of putty shrink as they dry, it sounds like you have one of those, if that is the case it doesn't matter how long you wait it will still shrink slightly.
In this case it's a safer bet to build up several thin layers of putty.

Place some more putty over the area and allow a day for it to cure, then sand it smooth. You may have to do this more than once to fully fill the panel line.
Don't forget to prime over the putty too to check for an even surface.

There are 2 ways to fix this.
1: What freakray said.
2. If the lines are just ghost lines, then you can use Mr. Surfacer 500 or someother filler primer. Spray it on.. then sand it down after 7 hours.
It sounds that the putty isn't fully cured when you start sanding.. and Mr. White putty is a 1 part putty so.. it cures by evaporating it's solvents. Like freakray said you should give at least 24 hours to be sure. Use a dehydrator if you have 1. The thicker the putty the longer it will take for it to cure.
Here is a link that might help you Body Mods How To by GTmike400
(http://www.kbkustoms.com/how2/GTmike/BodyModsHowTo/bodymods2.htm)

HTH
Steve

If you have a big panel line, just use styrene stripes or rods to fill the gap. It sands easily and doesn't shrink, and takes paint just like the rest of the body.

Thank you for all the suggestions. I will try and leave the puttied surface to cure longer before sanding it down. I was thinking of using the two part epoxy putty from tamiya to redo the panel lines, though it applies too thick. Anyway, I'll see how this second time around will come out. Thanks!