Q: I have an old house with an old door that has been painted over and over and looks horrible. It is on the side of the house that faces east, which does not help, as the door gets baked at sunrise. What is the best way to sand a door like this and repaint it so it might look decent for a while?

Arlington, Va.

A: An old door on an old house very likely has lead paint, so your first step isn’t sanding. You need to remove the old paint if you want a smooth finish, and sanding is not the way to start when lead paint is involved.

Stripping paint, even when it doesn’t contain lead, is a messy task. One option is to turn the entire job over to a company such as Antiques & Furniture Restoration in Sterling (703-437-7446; refinishing.org), which hand-strips, sands where necessary and applies new finish. Yasser Haridi, the owner, said the price usually comes to about $2,200. He uses Polarion X sealer and paint from M.L. Campbell (mlcampbell.com). These are two-component acrylic-polyurethane finishes, which Haridi said result in an especially smooth, durable finish. He has the paint custom-tinted at the factory to match whatever color customers choose.

If spending a few thousand dollars to repaint the door isn’t in your budget, you have other options. One is to take the door to a company such as ChemStrip in Upper Marlboro, Md., (301-420-9112; chemstripmd.com) to have the door stripped, then either paint it yourself or hire a painter for just that step. ChemStrip immerses doors or other objects in a vat filled with a chemical stripper, which takes off all the paint, and then neutralizes the wood so new finish will stick well. Mara West, the owner, said stripping interior doors starts at $175, and exterior doors start at $275, with additional charges for glass or elaborate trim. After seeing a picture of your door, she estimated the cost at $325-$350. Unless you pay a rush fee, stripping usually takes three to four weeks — or six to eight weeks if you want the company to apply new finish. You would probably be looking at temporarily installing plywood over the opening in your house.

Also, even though ChemStrip would remove all the paint, if you wanted to do the repainting yourself, you might still need to do some prep work. Doors exposed to a lot of ultraviolet light from the sun often have a peach-fuzz texture once the paint is off, West said, and you would need to sand that to get a smooth surface. If you don’t feel equipped to remove and transport the door and temporarily cover the opening with plywood, you can hire a handyman service for that.

You can also hire a painter to strip and repaint the door at your house, or do the work yourself. Either way, one benefit of this approach is that you could probably eliminate the need to keep the door off its hinges overnight. Any painter who works on houses built before 1978 must be certified and use lead-safe procedures or be working under the supervision of a certified renovator. You can check whether a painter or other contractor is certified by using the search tool at a website maintained by the Environmental Protection Agency, EPA.gov/lead. (The site also has links for states that maintain their own lists.)

If you do the work yourself, you should follow the same procedures that a pro needs to use, which you can read by searching online for an EPA publication, “Steps to Lead Safe Renovation, Repair and Painting: October 2011.”

Two requirements especially apply to stripping paint from a door. If you or a painter use a heat gun rather than a chemical stripper to soften the paint so it can be scraped off, the setting needs to be below 1,100 degrees Fahrenheit. Lead vaporizes at that temperature, which allows it to spread through the air and contaminate a wide area. (You don’t need anything even remotely that hot, because paint softens at 400 to 600 degrees.) And if you do sand to get a smooth surface, mist the area and use wet-dry sandpaper so the dust doesn’t become airborne. If you use a power sander, it needs to be connected to a vacuum with a HEPA filter, which captures superfine dust.

If you do the work yourself, you’re also responsible for disposing of the residue safely. Local requirements vary, so check with your waste disposal company or municipal hazardous waste agency. In Arlington, the Department of Environmental Services maintains a Household Hazardous Materials/Electronics Collection Recycling Center at the Water Pollution Control Plant, 530 31st St. S. It’s open without the need for an appointment from 9 a.m. to 3 p.m. on Saturdays, or you can make an appointment for drop-off on Tuesdays or Thursdays by calling 703-228-5000.

Once the paint is off and the surface is smooth, apply a primer topped by at least two coats of exterior paint. Choose a semigloss formula rather than matte, because it results in a smoother finish that doesn’t show fingerprints as easily. The water-based, acrylic paints sold at paint stores and home centers work well, provided you pass over the cheapest formulas, and if you later want a different color, they’ll be easier to paint over than if you used a specialty paint with a different chemistry.

Read the full label before you paint. Many paints work best when applied when the air and surface temperatures are 50 to 90 degrees Fahrenheit. If you paint the door off its hinges, you can set up an interior workspace to achieve that in any season. If you paint with the door in place, wait until it is no longer in direct sun, which would cause the paint to skin over too fast and not cure properly.

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