Rose, that is a good analogy and I am from New England. So no cultural issues lol. But I was taught that when you are saved and ask for forgiveness youre all set. And because you are saved, you are clean... I don't know maybe it just needs sometime to settle in for me to understand it enough to accept it as true. I also don't have a Catholic bible, so you might feel what I have is incomplete, but it's what I have always had so I have some "catching up to do" if you want to say.
I've been told the same thing you were, that once we're saved, we're washed in the Blood and we don't need anything else. But that doesn't stand to reason. Unless we die within seconds of being saved, we're going to sin again. We're going to need to confess our sins and somehow, the stain of all that sin needs to be dealt with. So the concept of "once saved, always saved," really doesn't work unless you want to see it as a license to commit any sin in the book. (And we all know people who've used it that way, too) That can't be right.
The Catholic interpretation is more that Our Lord's death made it possible for our sins to be forgiven and that we can go back, as necessary, to confess our sins. The cross doesn't force us to be saved; it gives us the option and we need to make that choice every day.
I have another analogy. I've used cotton diapers quite often for my seven kids. Occasionally I've had a few that I've soaked and bleached and worked at, but they are stained for the duration. They're clean
, but they're discolored. Our souls can be like that after certain sins, or after a lot of any sin. Over time if we really turn away from sin, this life might slowly wash the stain away, but we will likely still reach the end of our lives with a somewhat discolored soul.
Purgatory is God's gift to us so that we can go to Heaven fresh and clean.