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Painting knotty pine

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  • 08-05-2014 1:53pm
    #1
    cosmowillie53
    Registered Users Posts: 442 ✭✭


    I have some new knotty pine doors to paint White.
    I am using Johnsons water based primer undercoat.
    How many coats should I apply to before I apply the finish coat(s). I want to be sure the knots will not be seen.
    Thanks


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    #2
    CarrickMcJoe
    Registered Users Posts: 3,379 ✭✭✭CarrickMcJoe


    You should have either dabbed the knots with Shellac Knotting first or primed the timber with BIN primer which is Shellac based. This prevents the knots bleeding through the finish coat.


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    #3
    cosmowillie53
    Registered Users Posts: 442 ✭✭cosmowillie53


    Thanks for reply.
    Unfortunately I have a few undercoated at the moment. I have two coats on at the moment. Should I continue with another undercoat or just finish of with two finish coats ?
    I will use the Shellac for the other doors.
    Thanks.


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    #4
    jack of all
    Registered Users Posts: 2,361 ✭✭✭jack of all


    It doesn't matter how many coats you put on now, eventually the knots will bleed through any subsequent oil or water based paint. If the knots were anyway visible I would rub back the larger ones (you can disregard any of the smaller pin knots) with coarse sand paper and then treat with Zinnser BIN, as already suggested. Failing this just proceed to finish coat but accept that you may have to redecorate in a few years time; but bear in mind that a lot of painted doors and trim never saw shellac knotting in the first place.


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    #5
    cosmowillie53
    Registered Users Posts: 442 ✭✭cosmowillie53


    Thanks for info.
    There are a lot of knots so probably just best to finish with two coats. If I get a few years before repainting I can handle that. As you say there are a lot of doors out there painted without shellac however, since I now know that's what should be used I will do so one the remaining few doors.

    Thanks.


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    #6
    CarrickMcJoe
    Registered Users Posts: 3,379 ✭✭✭CarrickMcJoe


    Any raw timber, coat with BIN primer first. It may be ok to coat the painted timber also with BIN. I think it will hold back the bleeding.


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    #7
    game4it70
    Registered Users Posts: 2,121 ✭✭✭game4it70


    Jack of all is right saying the knots will bleed through.Sometimes the can bleed/stain after only a few months but it also can take some time.

    The shellac based products like BIN primer are good for prevention but are a pig to use if coatiing up a full door and not just the odd knot.
    Aluminium wood primer is easier to use if coating full doors.

    Whatever product you use make sure you sand the doors well after the 1st coat with 80 or 100 grade paper and use 100 grade or sanding sponges after the 2nd coat.
    I'd be carefull when sanding that you dont "break the seal" of the primer over the knots causing them to bleed through.If some knot look a bit bare oafter sanding touch them up with the primer before using your normal undercoat.


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