Issue in UV Map while texture painting

Hi to everyone,
I’m new of Blender (just only one month) and as attached, while I was painting a MESH (see red circle), the color also goes out (see red arrows), drawing random lines.
I don’t exactly know if it depends on my PC or by a wrong set, but I cannot get rid of this mess in every UV Unwrap I do for each different draw.
Someone may help me ?

Attachments


You need to supply a link to your blend file for others to be able to check it out. You can upload it to http://www.pasteall.org/blend/ and reply with the download link

Sorry, I uploaded right here : http://www.pasteall.org/blend/33329

Huge faces with a lot of vertices around (more than 4 actually) are called n-gons and they are bad in finished modeling. Sometimes you can get around by using n-gons only on flat surfaces and having ring of faces going around them in the same flat plane.
This of course is a bit tedious manual process for the figure you have. I have used Solidify modifier with 2 additional Materials to get face rings, J key to connect vertices to cut n-gons in smaller ones.
If you do not intend to render backside delete back faces- this will leave more texture space for the visible part.

UVs do not like if there is no space between so called islands - unwrapped group of faces or if such islands are overlapping. Adjust Margin value on T-panel bottom or F6 popup window immediately after unwrap.

After this painting does not show any artifacts:
http://www.pasteall.org/pic/81306

Thanks for your help, sincerly I have not understood your process but I’d like to let you know that, with BLENDER 2.70A I got rid of this issue without doing anything but, with 2.71 ->2.72b the issue remains…

Good to know, thanks.
While in some 2.70 i could not see anything being different, 2.69 was doing just fine, as you say.
Still, UVs without bleed margin and ngons left are issue for the recent versions.