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Step-by-step instructions for finishing wood windows and doors

Step one: prep the wood surface

  • The wood surface may require light sanding to remove rough surfaces or construction residue
  • Use 180-grit or finer sandpaper on a sanding block with an edger; sand with the grain; avoid touching the glass with the sandpaper
  • Remove all sanding dust with a tack cloth before applying the finish
  • Do not use steel wool: the fibers might get caught in the surface of the wood and rust when exposed to moisture

Step two: clean the glass

  • Remove sawdust, grease or caulking on the glass using a small amount of mineral spirits
  • Clean the glass with a vinegar-based window cleaner (an easy recipe is one part white vinegar to one part water)
  • Avoid ammonia-based cleaning products that can cloud the glass
  • Avoid getting cleaning products on unfinished wood, which may discolor it

Step three: apply the finish

  • Before you begin
    • If your window or patio door has a removable interior glass panel, remove it according to the manufacturer’s instructions and finish the wood between the panes, in addition to the room-side wood; make sure the finish has fully cured (according to the manufacturer’s instructions) before reinstalling the glass panel
    • Avoid getting paint in the breather or weep holes* on the window sash or door panels, or any other finishing products on the weather-stripping or any vinyl parts, which may compromise performance
    • If paint, stain or finish gets on the mohair weather-stripping, blot the weather-stripping thoroughly with a rag, allow it to dry, then flake off any residue with your fingernail
    • On double-hung windows, do not paint, stain or finish the vertical sash edges (the wood part that slides up and down against the frame), which may cause the sash to stick
    • On patio doors, finish all exposed door panel edges to reduce the probability of warping

Applying a stained finish

  • Pella strongly recommends the use of a good-quality pre-stain wood conditioner to reduce the possibility of a blotchy-looking or uneven finish
  • Ask your paint professional to recommend a pre-stain wood conditioner, stain and exterior-grade finishing coat that are compatible
  • Apply the pre-stain conditioner according to the manufacturer’s instructions, then apply a good quality stain
  • Finish by applying three coats of exterior-grade finishing coat, such as polyurethane

Applying a painted interior finish

  • The most important thing to look for when choosing your paint is good blocking resistance — the paint’s ability to resist sticking; failure to use a high-quality, nonblocking paint may result in a window or door that sticks shut even after the paint has dried
  • Ask a qualified paint professional or nearby extension office to help you find a paint with good blocking resistance; a high-priced or name brand can of paint doesn’t necessarily mean good blocking resistance
  • Ask your paint professional to recommend a wood primer and paint that are compatible, and if sanding is required between coats of paint
  • Read and follow the manufacturer’s directions for using your finishing products
  • Apply one coat of a quality wood primer
  • Apply two coats of a high-quality paint with good blocking resistance

After finishing with paint, stain or clear coat, allow the windows or doors to cure completely — per the manufacturer’s directions — before closing them or reinstalling patio door panels or removable interior glass panels

Finishing removable wood grilles

  • Grilles should be removed before finishing and sanded lightly with 180-grit or finer finishing sandpaper; always sand with the grain
  • Before you begin finishing, determine which side of the grille will face the room: the side that slides over the brass tack will face the exterior; the longer, tapered side will face the interior
  • For a stained or natural finish, follow the same steps as the stained interior finish
  • For a painted finish, use the same primer and paint as used for the interior and/or exterior of your windows or doors
  • Be sure to finish the grille ends to help control potential condensation

Finishing wood exteriors

  • Paint wood exterior windows immediately after installation; the factory-applied primer is not intended to last long
  • Follow the steps for painting as instructed above; use two coats of a quality exterior trim paint
  • Do not use wood stain or varnish — these finishes will not provide sufficient protection from the elements

Finishing entry door systems

  • Before finishing your entry door system, determine if it is premium steel, fiberglass (wood-grain or smooth-grain) or wood (some older entry door systems may still be made from wood)
  • Failure to finish your entry system in a timely manner may void its warranty
  • Wood-grain fiberglass doors may be gel-stained for a beautiful look of wood or painted to complement the home’s exterior color
  • Smooth-grain fiberglass doors must be painted, not stained; they are not factory-primed because no priming is necessary
  • Steel doors are usually factory-primed and can be painted, but not stained
  • Exterior frames are usually primed wood or clad (aluminum or vinyl); consult your retailer
  • If you paint your door panels, ask a qualified paint professional to recommend a quality paint with good blocking resistance; failure to use a high-quality, nonblocking paint may result in a door that sticks shut even after the paint has dried
  • Step one: prep the door panel and sidelights
    • Gently wipe dust with a clean, dry cloth
    • Examine the door panel and sidelights for possible smudges or fingerprints made from normal handling and remove with warm water, rubbing lightly to prevent damaging the surface; if necessary, clean the door with mild detergent, rinsing thoroughly, and let surfaces dry completely before applying finish
  • Step two: apply the finish
    • On a wood-grain fiberglass door, use gel stains only — not traditional wood stains
    • Apply the gel stain and clear finish according to the manufacturer’s directions, always applying the stain in the direction of the wood grain; be sure to finish the door edges
    • If you are painting a wood-grain fiberglass or steel door, sidelights and glazing frames, no priming is necessary
    • Paint all exterior surfaces, including exposed door panel edges, promptly with two coats of quality exterior paint to help reduce the chance of warping; don’t forget the top edge
    • Paint all interior surfaces with two coats of quality interior paint
    • Paint wood exterior doors immediately after installation; lightly sand if there are rough surfaces or construction residue; no primer is necessary; use a high-to-medium gloss quality exterior paint
    • After finishing the entry door system, allow the door to dry completely in accordance with the paint manufacturer’s directions before closing it
  • Step three: finish door and sidelight frames
    • Paint the exterior wood frame immediately after installation; the exterior wood frames are usually factory-primed, but it is not intended for long-term exterior exposure
    • If the exterior frame is clad with aluminum or vinyl, it doesn’t need painting; clean the surface with warm, soapy water; stubborn stains and deposits may be removed with mineral spirits; DO NOT use abrasives, tools or scrapers that might damage the surface
    • Interior wood frames that are factory-primed should be cleaned (see cleaning instructions above) and painted promptly with two coats of quality interior paint
    • Interior wood frames that are not factory-primed may be stained; apply the stain and clear finish according to the manufacturer’s directions

General tips

  • Failure to use the right type of paint will result in a window that sticks shut — even after the paint has dried
  • Remember, aluminum-clad exterior windows, doors or patio doors need no painting or staining
  • Staining is not recommended for wood or steel exteriors
  • For painting the wood exterior on patio doors, follow the instructions listed above for wood exterior door painting
  • In general, exterior window and door paint projects do not require a primer before painting
  • When in doubt, follow the instructions provided by the paint or stain manufacturer or ask a qualified professional for help

What’s the best buy for house paint or stains?

Buyers beware — exterior house products can vary greatly in terms of endurance. Considering all the weather elements outdoor paints and stains are exposed to, it’s important to buy a product that’s designed to stand the test of time for window and door projects, at least four to five years.

* Breather holes are small holes or openings intentionally manufactured into a product that allows a space to take in the fresh air and let out stale or humid air; weep holes are small holes or openings intentionally manufactured into a product that allow water to drain out of a sill or bottom rail cavity.