I'm repainting a wall and as per instructions I've washed down the
wall with sugar soap solution. However, I'm having a very difficult
job removing all traces of the soap.

I've rinsed the wall down with a damp sponge several times, but
there's still a residue of soap left. It's not visible when dry but
when you wipe the wall with a clean cloth, foam appears showing that
there is still soap there.

Does this matter? Can I go ahead and paint or should I remove all
traces of sugar soap? And if so, how?

thanks,

n