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Exterior Window Painting

I have a home that was built in 1987. The windows are wood and I can not get the paint to stick to the windows for more than 12 months. The latest round of painting I tried using a Minwax product "wood hardener" followed by two coats of a good water based primer and two coats of the final color. The paint hold to all but the lower sach and it peels over time. What can I do short of replacing the windows to get the paint to stick. Any and all suggestions with specific products would be greatly appreciated.

Re: Exterior Window Painting

HIghupguy -

When wood peels to bare wood, you can be assured that moisture is probably the culprit. You do not state what kind of glazing your windows have. Many windows would have a plastic type strip which would hold in the glass, Unfortunately, these strips were not very good at preventing water from working its way into the wooden frame. These strips were usually made of PVC plastic which deforms at temperatures of about 130 degress, a surface temp which is attainable on a hot summers day. If there are no signs of this plastic moving away from the glass, try a little bead of latex where the plastic meets the glass. Also, when painting the sash, deliberately go up on the glass about 1/32nd of an inch (this should be done with any wood window).

In any case, try to determine how water might be working its way into the wood of the sash. In cold climates, windows will often sweat during the winter and work its way into the horizontal surface of the sash. Is the interior paint in good shape?

Unless you stop the water infiltration, NOTHING will hold to the surface and untimately the sash will rot. Also, once the water has been blocked, allow several weeks of good drying weather for the wood to dry out. If you paint over wood with about 12% moisture content or higher, the paint will fail. Bare the wood totally and allow it to thoroughly dry out before primeing and painting.

Re: Exterior Window Painting

Thanks for the advice. There is no plastic piece. The window seats into a wood frame and there is silicon bead to hold the glass. When the seal has failed I have replaced the glass and over filled the silicon and wiped away the extra.

I guess I could apply a bead of silicon along the glass and wood frame and try to eliminate the wood penetration to the back side of the window frame as you suggest.

Interior paint is in good shape and no issues there.

I will try the same process I described but also apply a bead of silicon and paint it as well at the window frame.

Re: Exterior Window Painting


Pure silicon does not accept paint. GE does make a paintable silicon caulk which is available at HOme Depot.

If you can remove the sash, take it into the garage and us a blow torch to remove the paint from the wood. Be careful to shield the glass from the heat of the torch or it will crack. A belt sander would also remove this paint rapidly. When removed and sanded smooth, I would prime the bare wood with an oil based primer, followed by your finish coat.If the bottom edge of the sash which sits on the sill is not primed and painted, do so. This edge if left exposed might also wick water upward into the wood.

Incidentally, the Minwax Hardener was not intended for the purpose you were using it. It is used to help solidify partially rotted wood before the application of Minwax Woodfiller, a polyester product similar to Bondo auto putty. It would be removed with the sandinging anyway.

Re: Exterior Window Painting

When painting exterioer wooded windows i woud highly recomend a oil based primer such KILZ oil based primer comes in white can with red lettering sand to bare wood or as close as possible and use clear sillicone (small bead)behind window pains between glass and frame remove old glaze and reglaze two coats of oil based primer one coat sand then second coat but make sure weather is good no rain in forecast and also make sure your window fully seats on window sill. good luck

Re: Exterior Window Painting

Some correction to the above post is needed:

The Kilz Original oil primer noted above is for INTERIOR only!!

There's primers better than Kilz out there...I'd use Zinssers' Cover-Stain; or, if you're near a C2 dealer, use their Exterior oil primers. Top-notch primers like these need at least 12 hrs. to cure b4 painting.

Depending on your windows condition, dig out all old putty, prime the channel with a good oil primer. Oils from some puttys can leach into the wood if you don't prime the channel.
Then, of course, prime/paint the glaze/putty when it's dry!

As stated earlier too, use a good paintable Exterior-rated caulking. DAP & Polyseamseal makes good ones.


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