Pore-O-Pac grain filler woes

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by Boris Bubbanov, Oct 15, 2008.

  1. Boris Bubbanov

    Boris Bubbanov Member

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    My results with this just get worse and worse.

    It occurs to me that the binder was all on the top of the can, inadequately mixed, and than now there's just not enough of it to make the product hold together, so that it can be worked.

    Thinking about adding some linseed or tung oil to some of what remains in this can, and trying it on a sample.

    Any suggestions, or is everyone using McFadden/Bartley's/Behlen instead?

    Much obliged.


    Bubbanov
     
  2. Chris Scott

    Chris Scott Silver Supporting Member

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    With what I know re. grain filling (which as often as not is a tedious pain in the ass) my suggestion would be to mix the stuff thoroughly, sand it all off and start over - I know it's like the last thing you want to do, but my experience says it's likely the way to the best results, no matter which brand, (oil or waterbase) you end up using.

    Is it ash? fwiw, I've been getting great results by carefully brushing and vacuuming all the dust out of the pores before application, and with a single-edge razorblade, applying the stuff in only the pores I can see when I hold the body up in the right light. I then carefully sand back with 320, brush/vac, and check, check, check like a mofo for open pores, repeating as needed until I see no open ones.


    Mohogany is obviously a different deal altogether, so sorry if I'm off the track here...



    Best of luck!
     
  3. Jack Briggs

    Jack Briggs Member

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    You can add a little bit of pure linseed oil, and some naphtha or mineral spirits (for a longer open time) to extend the Pore-O-Pac. I've had a can that I've used for years this way. As long as it doesn't skin on top. Once that happens it must be skimmed to get to fresher material.


    Cheers,
     
  4. Bob V

    Bob V Member

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    Several recipes I've read call for mixing some mineral spirits into the batch until it becomes the consistency of X (which, depending on who you listen to, is anything from heavy cream to peanut butter). The point is, there's nothing wrong with thinning it if it makes it more workable for you. Problem is, if it's too thin it won't build much and you'll need to do several applications. Adding an oil might just lengthen the time it takes to cure, and that's pretty long before you can topcoat to begin with.

    Honestly I find the stuff to be a huge mess and it never quite fills the pores for me after I've wiped away the excess. Doesn't matter whether I'm using a rubber squeegee made for the purpose, a soft rubber float for grouting tile, a credit card, a broad putty knife, or a hunk of burlap. The last time I forced myself to use the pigmented Pore-O-Pac was to patch a mahogany top on an acoustic because I figured that's the type of thing that was already on the rest of the finish I was trying to match. If I'm finishing the piece from scratch, I prefer the water based grain filler from Target Coatings (HSF-5100) which is quite compatible with the rest of their finish line (Oxford and EmTech). It's much easier when the filler isn't colored because you can leave a little on the surface and it won't show - if it's tinted or pigmented then you have to carefully remove the filler and cut back only to the sealer without sanding through to the bare wood or stain underneath. I just haven't been able to pull that off (shame, too, because dark pores on ash would look nice...).

    I was startled watching a video on the Gibson site of a factory tour - the person the brushed the neck of a semi-hollowbody with some goupy stuff that looked like thinned-down Pore-O-Pack, then almost immediately wiped it off with a rag (without waiting for it to flash off). Off she went for a few coats of lacquer. Made it look easy. Hrumph.
     
  5. Boris Bubbanov

    Boris Bubbanov Member

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    Chris, these are mostly ash bodies, just a couple mahogany and one lacewood top as well. I like your idea about using air to clean the pores out thoroughly, I could definitely improve there.

    Jack, I will try the linseed oil. I will also add the Pore-O-Pac reducer which I already have on one sample, and naphtha on another.

    Bob, I know I'm holding up progress here, I probably should switch to the Target line at once. Grain filling mahogany and walnut, but especially ash is so tedious; I've never met anyone who enjoys this process. I guess I just would like to prove to myself that I can get a good result at it (I've been meaning to learn this for years) and once I get it right a few times, I'll probably step into the new ages.

    Thanks to all.

    Bubbanov
     
  6. Mike9

    Mike9 Supporting Member

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    Grain filling is a real PITA - I use Bartely's and I'm testing Stew Mac water based filler. So far so good, but time will tell.
     
  7. DANOCASTER

    DANOCASTER Supporting Member

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    Bartley's ( a mix of Natural and Light ) for me

    Just the other day I grain filled 12 bodies. Beautiful day - all the shop doors were open - great tunes playing - and it was still such a PITA

    My wife asked why I was so "cranky" ?:roll

    BTW- I use a heavy squeegee and some burlap type stuff and I dont shoot a wash coat of lacquer FIRST. Apparently that helps but I've never tried it. I just apply the filler into a clean bare body on time ( once but thorough ) - then sand - then use a Nitro sand n sealer ( like 3 coats ) - then sand - then color coats

    I just try to do em in big batches so I dont bitch about it AS OFTEN :AOK
     
  8. Bob V

    Bob V Member

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    The problem with a washcoat before the grain filler is that I tend to sand through it unevenly when cutting back the grain filler; on the other hand it makes it easier to remove the excess filler that isn't in the pores.

    By the way, Boris, if you like the idea of cleaning your spray equipment with soapy water then check out the forum at TargetCoatings.com
     

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