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  1. #1
    Join Date
    Aug 2008

    Default New paint over glazing cracking

    I am in the end stage of reglazing a few old windows on our house in Vermont. These windows were installed in new construction in 1938. After figuring out how to remove the windows (took some doing) I have found they were pretty nicely made double hung 6 over 6's. I found some manufacturers marks indicating they were Montgomery Ward's windows. Interestingly, the counter balance are springs in channels on the inside of the windows, and more importantly, the windows had metal weather stripping/tracks on the sides which are so good at preventing drafts, I don't think they can be improved. Not a feature I anticipated, and one that took a while to figure out since the weather stripping channels must be slipped out of the sash before the window will come out.

    I spent considerable time removing all the old glazing, prepping the frames, and reglazing the windows. I used an alkyd primer, then the glazing compound. I then let the windows sit for 2 weeks to allow the glazing compound to skim over. I thought this was sufficient, but may have been wrong as it has rained here almost every day the past month and has been unseasonably cool and damp. I then used the alkyd primer over the window frames and glazing compound, let this dry overnight, then put one coat of satin latex over this. I went out tonight to put another coat of latex paint on and found that several windows, but not all, exhibited generalized cracking. This is truly disconcerting given the amount of time already invested in reglazing these windows.

    So, does anyone know what may be going on?? The paint seems to be adhering fine to the primer and not peeling up. I am guessing that the glazing is either off gassing or moving (expanding??). I really do not want to remove the new glazing and start over. If I wait for a while (a month?? more???) then put another coat or two of paint on, will I be OK, I did this same process on a bunch of windows last year and had no problem. Anyone have a clue??

    Thanks in advance


  2. #2
    Join Date
    Aug 2007

    Default Re: New paint over glazing cracking

    I then used the alkyd primer over the window frames and glazing compound,

    Am a bit confused, perhaps. Does this mean that the sash frames were exposed to all this rain without any primer on them??? ....or that you were were adding an additonal coat of primer on the wood at the same time you primed the glazing?

    Type/brand of glazing? Please tell me it wasn't the Dap stuff that comes in a caulking tube.

    Any chance of a pic or two? (Could be helpful)

    What does unseasonably cool mean for your locale?

    PS- I'd be bent,too. 6 over 6 sash is a lot of work.

    PS again - What brand of oil primer & latex topcoat did you use? Weather conditions at the time?

    You did leave the oil primer dry before you applied the glazing over the top of it...yes?
    Last edited by goldhiller; 08-14-2008 at 10:15 PM.

  3. #3
    Join Date
    Aug 2008

    Default Re: New paint over glazing cracking

    Hi ****hiller

    I guess I left out a few specifics. All of the work done on these windows was done in my barn which has no heat or air conditioning, and is exposed to ambient air (but not rain or precip). So no exposure to water.

    I primed the frames first (with Benjamin Moore's best alkyd primer). Let this dry, then glazed the windows. For this I used DAP's regular glazing compound, which is a traditional linseed oil based glazing compound.

    I let this skim over for 2 wks. I then primed the whole window with the same alkyd primer, followed by one coat of satin latex paint. Sherwin Williams Pro-Classic.

    It has been raining and fiarly humid here for the past month. Temps have been 60-70 F and dropping some at night, but nothing near freezing.

    I attached a pic of the cracking (hopefully),

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  4. #4
    Join Date
    Aug 2007
    Portland, Oregon, formerly of Chicago

    Default Re: New paint over glazing cracking


    Off hand, My guess is that the primer was not thoroughly dry before you top coated it with the latex. Coolness and humidity definitely slow down the drying time of most paints, oilprimer included. It may have been dry to the touch, but still contracting. The top coat of acrylic is drying at a different rate and therefore pulling away and forming the cracking lines. Something similar occurs when you paint over urethane caulk too soon with a latex paint. Linear cracks will form in the film of the paint. The urethane needs at least 24 hours of curing before painting over it. Oddly enough, urethane cures faster in high humidity, unlike most paints.

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