Absolutely - just not with soap, lanolin will prevent a good adherance for paint. I noticed on the start of your build that you hadn't cleaned the sides before you started soldering. I use one of those inch diameter fibre brushes, no use for getting rid of excess solder but really good at cleaning brass. Not cleaning the brass sides can lead to problems in soldering, not all etched sides are cleaned of their etching fluid.
Cleaning after finishing a soldering session is a must, make it part of your modeling regime/session. It will pay dividends. If you want to know how there are plenty of suggestions on this site just search for them.
Mike