PATRICIA BLACKMUN is up the ladder by 11, on the north side of a brick and stone split level in North Arlington. Birds chirp in trees almost level with her head and drown the rasp of her scraper as she prepares a window for caulking. Paint chips fall into the hair of people below.

Blackmun comes down and stands in the wet grass, hands in the back pockets of her jeans, inclines her head and squints into the sun, smiling. This is the first sunshine in almost a week, and in the last few days Blackmun had painted the shutters she'd taken home in anticipation of that anomalous monsoon. The windows are next: scraping, caulking, glazing, then the painting.

Blackmun supports herself and two children as a housepainter, an independent who "got in through the back door."

"Seven years ago I painted my own house, and a neighbor came over and admired the job so I painted hers, too, and it's been word-of-mouth business since then."

She regularly hires three or four helpers, none of them professional painters: as often as not, vacationing schoolteachers. She arranges her schedule to work indoors in winter, outdoors in the warm months and hike mountain trails in summer.

"I hiked the Appalachian Trail over the last yree years: about 1,000 miles in the first year, 600 miles the next and the last 400 or so last summer. This year I'll probably do the Lake Placid trail in upstate New York."

She climbs the ladder and resumes scraping while she expatiates on the fine points - like how many layers of old paint can be allowed to accumulate before the dread "moisture buildup" sets in, causing cracks and bubbles on the outside and wreaking rot and ruin on the wood underneath.

"That's something we don't know yet, because paints change so much. The old paints used to be chalky, almost like whitewash. The paint would wash right off a house, which I think was an excellent idea. Now paints are improved, and that doesn't happen any more."

"If I had a choice, I'd go back to those old paints, which washed off every few years. Then when you painted again, you'd be actually painting on the wood, and it felt good and looked good.

"I use latex all the time now, unless someone insists on oil-based paint.

"But the first thing you've got to do is get up there and scrape. Take all the loose paint off and caulk all the holes. You should clean your gutters too, then scrape and prime them with a galvanized undercoating."

She comes down the ladder for a cigarette.

"Now you're ready to start your windows. Scraping, caulking and new glazing if the old glazing is bad.

"How long the caulking will last depends on how it's put on. If it's put on smoothly, with no air bubbles, it'll last a heck of a long time. But if it's done fairly sloppy, like in most cases - just put on with a gun, and not gone over again - mm-mm," she frowns.

"Whether you have sand or not depends on the surface. With this kind of exterior work: no, unless you've got ridges or corners, which can peel.

"Next you're ready to paint. Hopefully with something decent, not a cheap brand.

"A department store brand, if it's their best of the line, is usually excellent paint. Almost any company: If you use their best, it's good paint. But they all have what they all 'realty products,' you know, lower-line products: no good.

As for painting stone and brick - "I don't recommend that at all. I have never done it for the first time for anyone. If they come to me and say gee, they want to do it, I do my best to talk them out of it. I've repainted stone and brick. Even with the brick it's a difficult job if the brick starts sanding, which happens after some years.

"I think it's a mistake to paint stone or brick. Why go to that expense every five or six years when it's a surface that's designed not to have such an expense?

"One of best ideas for people who are going to paint their own houses, I think, is the idea of one side every year. It keeps the expense down, and every four years the house has been completely repainted. It never looks weathered; it never looks bad.

"It's a good thing for a homeowner to do himself, because painting a whole house at once is a really massive job. It can take you whole vacation, or every night for two months when you get home from work.

"The different ages of the paint jobs on each side of the house don't really show up. Most of the houses I've done this on, I've done it in white. Some other colors might fade more."

Although price depends on several variables, Blackmun gives as a representative figure the $15-20 she will charge for the French windows she's working on now.

Her reputation among customers is so imposing that many of them grant her broad discretion, even to this extreme:

"One of my customers was in Europe when I painted his place. He left me a key, said, 'While I'm gone, please paint the apartment. Thank you.' And that was it. He didn't even know me. But that's the kind of word-of-mouth business I do with people."