Sanding sealer or grain fill first?

Discussion in 'Finely Finished' started by RichCuellarPDX, Aug 3, 2021.

  1. RichCuellarPDX

    RichCuellarPDX Tele-Meister

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    Hey Everyone-
    Im refinishing a mahogany Thinline Tele, and I was wondering; Should I fill the grain first and THEN spray the sanding sealer? or vice versa?

    My plan was: grain fill, sanding sealer, primer, color, clear?
     
  2. J. Bonkosky

    J. Bonkosky Tele-Holic Silver Supporter

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    Sanding sealer first.
     
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  3. telepraise

    telepraise Tele-Afflicted

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    Does the filler you're using have the potential to alter the color of the mahogany? If so, you may want to seal before filling. Alternately, some folks fill first because they want to sand back afterwards, leaving the filler only in the pores.

    edit: seeing the words primer and color suggests you're going for an opaque color, in which case it doesn't really matter. Just make sure you fill the grain at least twice and let it dry a long time before leveling. Filler tends to shrink back over time and you don't want those pores dimpling through your flat finish after all your hard work.
     
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  4. RichCuellarPDX

    RichCuellarPDX Tele-Meister

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    Great! Thank you for the advice. When you say let the grain filler dry a long time, how long is that? 24 hours?
     
  5. trev333

    trev333 Telefied Ad Free Member

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    a week would be good if you're not in a hurry..:)

    or less if you're in a hurry,....:D
     
  6. trev333

    trev333 Telefied Ad Free Member

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    it kinda depends on the product you are using, really... ;)
     
  7. Freeman Keller

    Freeman Keller Poster Extraordinaire

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    I pretty much follow StewMac finishing schedule (I only use lacquer). Their dry/recoat times are reasonable.

    https://www.stewmac.com/video-and-i...ish-repair/nitrocellulose-finishing-schedule/

    I stain first if I'm going to. Then pore fill using Zpoxy which I selected after doing a side by side comparison. Seal with vinyl sealer. Color coats if I'm going to. Clear on last. Wet sand and buff.

    I don't actually use "sanding sealer" or "primer". In my opinion sanding sealer is just lacquer with high solids to build film thickness, I can do that with the lacquer itself. Primer creates an opaque background for color, most of the color I shoot is transparent and I want to see the wood thru it.

    Remember the cardinal rule of any finishing experiment is to practice on scrap of the same wood with the same materials in the same order.
     
    Last edited: Aug 3, 2021
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  8. trev333

    trev333 Telefied Ad Free Member

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    sanding sealer,(if I use it) I slap it on, sand back to wood, slap another coat on, sand it back to wood... then start with any finishes with very little sanding sealer left on the surface...
     
  9. Freeman Keller

    Freeman Keller Poster Extraordinaire

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    I will and one more thing to the above. I learned to do stains in the old Gibson way dating back to the Loar era - the stains are applied directly to the wood, possibly sanded or blended, then a clear finish is applied of that. There are some people who advocate for sealing the wood before apply the stain. I did a little experiment with some figured maple and two sealing mediums - shellac and vinyl - and decided that for my work I greatly preferred applying directly to the wood, then sealing that.

    Another question follows that - should stain be applied before or after pore filling? Again, with the products I use I feel that staining first works the best (and that is what StewMac recommends) but I think that might change with different pore fillers.

    The cardinal rule is to practice on scraps of the same wood.........
     
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  10. Drak

    Drak Tele-Afflicted

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    This is a trick question.
    The correct answer is to remove the sanding sealer from the menu.
    For a solid (opaque) color, the pore filler and primer will get you to level for your opaque color coats.
    You (generally) never use the word 'primer' unless you're referring to an opaque finish.
    You never use products unless the finish requires them, or something from them, and this finish does not require sanding sealer.
    (Actually sanding sealer is never, ever required, I never use the stuff, although some find it useful)
    You always minimize potential (negative) product interactions by never using anything that isn't required.
    Sanding sealer is completely superfluous to this desired outcome.

    So unless the word primer was used erroneously, this is a trick question.
     
    Last edited: Aug 3, 2021
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  11. Sea Devil

    Sea Devil Friend of Leo's

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    The last discussion of this got pretty heated. It seems to have caused one member to stop posting. In the interests of being agreeable and conciliatory, both approaches have their advocates. The "no sealer" POV is legit, too.
     
  12. pypa

    pypa Tele-Holic

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    Color
    Seal
    Fill
    Sand

    sealing helps protect the color and makes sanding the sealer easier. It is easy to leave residual filler on the wood which can lead to splotch under a topcoat. Sealing first helps the filler release easier to avoid this condition.

    If you color and or seal first, be careful not to pull filler from the pores or sand through to the color.
     
  13. RichCuellarPDX

    RichCuellarPDX Tele-Meister

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    Yes, I plan on an opaque color. What you say makes sense in that regard.
     
  14. Sea Devil

    Sea Devil Friend of Leo's

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    Don't listen to pypa, please. This is such an irrational recommendation that I'm tempted to call it trolling.
     
  15. whetherkings

    whetherkings Tele-Meister

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    I recently finished this mahogany body by hand, wanted a natural finish so didn’t use any grain filler. Literally just lightly sanded, stained and oiled.
     

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  16. jfgesquire

    jfgesquire Friend of Leo's

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    Wow, so harsh.

    I have seen this schedule referred to many times.

    I always put a shellac seal coat down first, especially when using a pore filler that's tinted so it doesn't stain the wood. And I've seen lots of people prefer to tint the wood before the seal coat.

    I have had the issue of the pore filler not staying in tiny mahogany pores and I learned it was from my sloppy sanding technique, sanding with the grain when removing the excess pore filler. And I know when to stop sanding the pore filler when my paper starts to hit shellac.
     
    Last edited: Aug 5, 2021
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  17. Freeman Keller

    Freeman Keller Poster Extraordinaire

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    Here is finishing a mahogany neck and rosewood body. I want to change the color of the mahogany to be closer to the rosewood - this is common for some companies like Martin. I'll try to show the steps in order and materials that I used.

    Guitar and neck bare wood sanded to 320

    IMG_6340.JPG

    Staining the neck with red-brown transtint stain dissolved in DNA. Not showing is painting a thin like of vinyl sealer on the light colored purfling lines on the headstock and body

    IMG_6344.JPG

    Neck stained

    IMG_6345.JPG

    I'm scraping the sealer and stain off to get a nice crisp line

    IMG_6346.JPG

    Pore fill with finishing resin

    IMG_6351.JPG

    Seal with vinyl sealer

    IMG_6352.JPG

    Clear lacquer top coats

    IMG_6356.JPG

    Sand and buff

    IMG_6359.JPG

    I frankly have never done an opaque color on mahogany - why hide the beautiful wood. However I have built a couple of red guitars with mahogany necks (and maple bodies). Here is applying the red lacquer

    IMG_3366.JPG

    Which is then followed by clear. On the red guitar I am still trying to see the grain through the finish. If I wanted it completely opaque I would have put a solid color primer on before the red.
     
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  18. Sea Devil

    Sea Devil Friend of Leo's

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    pypa's schedule only makes sense if the color in question is dye or stain and the whole process is followed by clear (or a translucent tint and clear). That would be fine. Otherwise, you have grain filler as your last stage before final sanding, and it will probably fall out or be corrupted by environmental factors. Read exactly as stated, it's at best incomplete. Filler over a solid color would yield a horrific result, and the OP mentioned primer in his first post, so we know it will be a solid color.

    I'm not making an effort to misinterpret it, but if a newbie read it as "solid color, sealer, filler, and out," I think they'd be really upset after following that advice. That's what freaked me out.

    In pypa's defense, he probably didn't see the reference to primer, did see subsequent posts about translucent finishes, and took it for granted that everyone knows you have to shoot something over the filler.

    Freeman Keller, that's terrific work! Absolutely gorgeous. We've seen the 335 before, but the acoustic's new to me. Thanks for sharing (or showing off your expertise, as the case may be)!
     
    Last edited: Aug 5, 2021
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  19. jfgesquire

    jfgesquire Friend of Leo's

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    When I read his post I just naturally assumed he was referring only to the steps up to and including the pore filler, not after, but after reading this I could see what your concern was. Good points. If Freeman ever succeeds at convincing us, everyone will be using resin and nobody will buy the Stewmac fillers.
     
  20. eallen

    eallen Friend of Leo's

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    I do quite a bit of mahogany but like all woods, it depends on the pore filler. Expoxy like Zpoxy goes on 1st first for me followed by vinyl sealer. If using a more traditional filler quality vinyl sealer 1st then pore, and another light coat of sealer. The sealer 1st keeps it from soaking in to have to use an abundance of filler as well as promoting good adhesion as sealer is formulated to do.

    If doing an opaque color it matters less, as does any reason for using mahogany in covering gorgeous color and grain. For opaque I fill, prime, color, clear. You will be priming with a solid color primer which also generally fills a small amount.

    Eric
     
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