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Sanding sealer instead of grain filler?

Discussion in 'Finely Finished' started by PearlJamNoCode, Feb 26, 2021.

  1. PearlJamNoCode

    PearlJamNoCode Tele-Meister

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    So I've completely sanded my guitar body, but it seems like my Stew Mac grain filler got lost in the mail.

    I have Stew Mac aerosol sanding sealer. Would spraying some coats of that take care of the grain? The grain is very minimal and not deep at all.
     
  2. _MementoMori_

    _MementoMori_ Tele-Afflicted

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    Some people fill shallow grain by creating a slurry of sawdust and finish. Basically you sand in your finish in kinda the same way you use wipe-on poly. Wait for someone else to answer though - I've never done this. I'm just regurgitating what I've read elsewhere.
     
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  3. Danb541

    Danb541 Friend of Leo's

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    What type of wood are you working with? Sanding sealer is a "sealer" not a grain filler. Grain filler is for filling open grained wood. That said, some types of wood don't really need grain filler and the sealer will do the job.
     
  4. BSG1

    BSG1 TDPRI Member

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    Depends on the wood, ash has really open grain, alder is tighter and maple even tighter. A quality finish is totally dependent on the prep work. I use Bulls eye seal coat applied by hand with a lint free cloth (old white tshirt) then sand again with 400 paper, do this 3-4 times and you should have a beautiful foundation for any top finish.
     
  5. PearlJamNoCode

    PearlJamNoCode Tele-Meister

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    The body is poplar. I'm leaning toward being patient and just waiting for the grain filler to come in the mail.
     
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  6. Freeman Keller

    Freeman Keller Poster Extraordinaire

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    I have never understood what "grain filler" was supposed to do. I know very well what porous wood like mahogany or rosewood or koa is like and why the little pores need to be filled and leveled because of the way lacquer shrinks back. This is rosewood, I did not do an adequate job of filling the pores, those are the little white marks

    DSCN1387.JPG

    Non porous woods do not need pore filling (duh). In their finishing schedule StewMac lists the following woods as being non porous - Maple, Spruce, Alder, Ebony, Basswood, etc. Poplar is not in that list and I've never worked with it so I don't know.

    Grain is something else but I really don't understand the idea of "filling" it. I do all sorts of things to highlight grain - stains and other materials that are absorbed at different rates to pop the figure on a maple top.

    IMG_4809.JPG


    Here is the back of that same guitar, mahogany with its little pores filled and leveled

    IMG_4810.JPG

    Anyway, if you are using nitrocellulose lacquer and sanding sealer remember that it will shrink back as it dries. You think you have a nice level surface but if the pores are not filled they will come back. If there are no pores then nothing to worry about.

    https://www.stewmac.com/video-and-i...repair/nitrocellulose-finishing-schedule.html
     
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  7. pvraghav

    pvraghav TDPRI Member

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    I recently applied a couple of coats of a thin cut of shellac on my poplar body and thought at that time it was adequate enough to fill the grains. After the first couple of coats of paint (I used Rustoleum rattle can spray), the grain was still visible through the paint. Numerous coats of paint and clear coat have masked it off a bit but the grain is still visible. So based on my experience I would say the sealer is probably not enough - assuming the sanding sealer is probably just shellac. I guess it depends on the cut too. May be a heavier cut would fill the pores better.
     
  8. Wyatt

    Wyatt Tele-Afflicted

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    Poplar is considered close-grain med and should beed a filler. You would beed to inspect the wood but building up several coats of sealer and sanding level should work
     
  9. eallen

    eallen Friend of Leo's

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    Poplar doesn't need grain fill. As a closed grain wood there are no pores to fill.

    On open grain woods like ash, mahogany, walnut... sanding sealer will continue to shrink a bit over time as it is meant to seal and fill scratches to the level of like 220 to 320 grit sand paper. As a result, if you apply it thick enough to use as a grain filler it will look fine for a while but the grain will show up down the road as it shrinks.
     
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  10. EsquireOK

    EsquireOK Poster Extraordinaire

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    You can use grain filler on closed-grained woods, and get some benefit from it. But it is not necessary unless you want an extremely smooth finish that shows no grain relief whatsoever, while also using minimal total finish thickness.

    Most people don't mind a slight relief of the guitar's wood grain, so they'd find the results of skipping grain filler on poplar (or alder or maple) acceptable; the sealer would do enough. If you want glass-like smoothness, however, use grain filler, as well as plenty of sealer.

    I, myself, would not grain fill poplar, alder, or maple. I like the slight relief that comes from going straight to a conservative application of sealer. For some guitars, I even like the "D.I.Y." home-sprayed look of going straight to primer or color coats on these woods, and skipping clear. For that look, three cans of lacquer straight onto alder is gorgeous, IMO. If, however, I was doing a vintage-accurate '60s Fender finish, I would use a very thick application of sealer, in an attempt to eliminate all grain relief.
     
    Last edited: Feb 28, 2021
  11. Dacious

    Dacious Poster Extraordinaire

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    Poplar probably doesn't need grain filler. Just sanding sealer should be enough.
     
  12. torodurham

    torodurham Tele-Holic

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    More on the subject of filler..I have not found a filler I completely like..tried aqua coat, old masters, system II 2 part epoxy, Z poxy..the epoxy's so far are ok..but still not to my liking..any suggestions? Mainly for mahogany...
     
  13. Vizcaster

    Vizcaster Poster Extraordinaire

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    Actually what you might need is a good sealer rather than a grain filler. Some sealers have the property of bridging and preventing the top coat from shrinking back to much for the grain to print through. Think of an old acoustic spruce top where you can see the growth rings and the scallops between early and late wood. That's not pores it's the surface of the wood. A good vinyl sealer or sanding sealer can minimize that effect of the topcoat shrinking in.

    It also depends if you're doing a solid color (likely for a poplar body? not a real pretty wood in and of itself, then again lots of antique cherry tables turn out to be poplar that was dyed to fake a cherry finish) then a good primer would help get things sealed and give you plenty of hard base to sand back level before your actual color coat.
     
  14. JohnnyNacho

    JohnnyNacho TDPRI Member

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    So far my favorite pore filler is a polyester resin. Might be sold as fiberglass epoxy next to the Bondo. Very rigid, good surface tension so it stays where you put it, has a slight tint but nothing noticeable in such a thin layer. I've used lacquer, shellac, and polyurethane as a topcoat without trouble. Work it in with an old gift card and please wear a mask, even outdoors. I forget where I read it, but supposedly polyester resin has similar properties to a ground layer used in violin finishing.
    A story too good to fact check: one can locate the schools of classical luthiery based on a heat map of scorch marks on ceilings above the stoves of cheap apartments, as cooking one's own varnish is a rite of passage. Polyester won't require a fire extinguisher, unless you try to mix the entire batch.
     
  15. Dr Chim Richalds

    Dr Chim Richalds TDPRI Member

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    I am a complete novice and am just to the polishing stage of my first build with swamp ash, but I have attempted the finish on this guitar several times and have started over several times, using different grain fillers. I’ve tried the stew Mac powdered grain filler, drywall compound, and almost recently aqua coat. BY FAR the easiest product to work with that has also yielded the best results has been aqua coat, but I will post my feelings on each product.

    stewmac powdered grain filler - I first used this in the mahogany color because I thought I wanted a dark grain fill under a semi transparent finish. This worked ok, but seemed to “pepper” the fine cavities in the wood rather than completely and continuously fill them. This could have been due to my application technique or perhaps I sanded too much after grain filling. I will say that it is imperative to use a solid coating of sanding sealer before applying these products because they will color the whole surface of the wood and require excessive sanding to just leave the open grain colored.

    drywall compound - I used drywall compound next. This overall worked very well, so long as you are ok with white grain filling (it dries white but can probably be tinted). It’s easy to thin and mix right out of the can and applies well and fills the grain pretty well. Sands easily!

    aqua coat- more of a gel than a paste and is highly workable. The first time I used this product I really felt like I was really leveling the guitar and filling the grain. I did three coats, but I think the last coat was redundant. I got a really flat, smooth surface on which I shot my clear gloss lacquer. I love the way this was applied and how it didn’t alter the natural colors of the wood and grain.
     
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  16. RLee77

    RLee77 Friend of Leo's

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    This sounds like a great filler. I have timbermate that I was planning on using on a black korina tele body, but the clear gel aqua filler interests me since no worries about discoloring the korina.
     
  17. Freeman Keller

    Freeman Keller Poster Extraordinaire

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    You have already said you tried and didn't like Zpoxy but that has become my standard filler for mahogany and I build most of my guitars from that wood. There are quite a few examples here

    https://www.tdpri.com/threads/zpoxy-for-pore-fill-and-grain-enhancement.940522/
     
  18. old wrench

    old wrench Friend of Leo's

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    Aqua Coat is a great filler - it's easy to apply, dries quickly, and it's very easy to sand.

    Right out of the jar it looks like white grease, but it dries clear.

    It's easy to tint or dye it as well if you want your filler to contrast.

    A jar of it goes a long way and it keeps without getting moldy or nasty.

    It'll work right into the pores and nooks and crannies, but it's not meant for thick build-ups - just as a filler.

    I usually use a a flexible spreader, like for Bondo, but a credit card or those fake credit cards (with the plastic laminated to them) they send you in the mail works just as well :).

    .
     
  19. Dr Chim Richalds

    Dr Chim Richalds TDPRI Member

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    yes, the credit card has been the best spreader. It helps spread and (for lack of a better term) really MUSH the aqua coat into the pores. Then scrape scrape scrape.

    since its clear you can go nuts and apply liberally and just wipe excess from your pickup cavities and routs with a paper towel.
     
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