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.