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Grain Filling


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Alrighty,

So... I have literally been trying to figure out grainfilling for about 7 years.

I have used every mainstream grainfilling product and other methods.

WHAT THE HECK IS THE SECRET??

Usually i can figure things out... but dang. All this time, and i have still never gotten it down.

Conventional grainfillers,

i have watched numerous videos on how to do it. It always seems like they apply it, rubt it in, and squeegie it off. I do the same, and it just stains the grain, and when i squeegie it off, it just pulls it out of the grain.

I have tried over applying it to cover the whole thing, and then by the time i sand it down, the pores re appear because it is harder to sand than the wood is.

What is the secret? I am absolutely tired of trying this for years without success.

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Hey Luis,

I use Timbermate as well watered down with distilled water. It will stain the wood though. Also using shellac is another method I use. Just spray it or brush it on and sand it back. YOU might try a combination of both. :) Seal the wood with shellac (a light spray coat), use the timbermate to actually fill the grain, then sand back to bare wood. I have used this before when using paduak and maple together. It keeps the paduak color from being ground into the maple while sanding. :)

Take Care,

Mike

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Thanks for the suggestion mike!

I have an old explorer body i am doing tests on now. It has HUGE pores, even for mahogany. It should be easy to fill, but even when i water it down a lot and really work it in, when i sand it back, they still arnt filled. I dont understand how this can be so complicated.

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Sometimes you just need to apply a couple of coats of filler to completely fill up the pores. Big pored timber like mahogany probably just accentuates the need for multiple coats.

In my experience if the filler is pulling out of the pores when squeegie-ing the excess off it's probably dried too much to be manipulated any further, or it's been mixed too viscous to start with. Timbermate dries very quickly and doesn't have an awful lot of working time.

Regarding epoxy as a pore filler, I've had luck using a scraper to remove the excess rather than sanding - much less effort and almost no nasty epoxy dust to contend with.

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Louis, do you know anything about French polishing with shellac? I have no great deal of experience with it myself, but I did test it once to see if I could pull it off. One thing I did notice was all that rewetting and rubbing with alcohol certainly did fill all the pores and leave a level surface. I did not go back and sand back to the wood--but shellac is very sticky. I think it would be one of the more difficult things to pull out of the pores.

Hell, I think I'm going to try that myself on my next build.

The last thing I did was filled with Z-poxy. I applied it very thin with my fingers (gloved) and rubbed it in like tru oil. But on that one I left a layer above the wood surface, so I didn't fight it pulling out of the pores.

I also did one where I sanded the surface with 320 and left the dust in the pores. Then I hit it with thin CA and sanded that back. I had to repeat it a few times but you could see the dust in the pores each time so it was easy to tell when you were done.

I have never found anything that worked without needing a second or even third application......I have high hopes for a french polish method though....

SR

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I've used chemcraft porefiller and I've used dry wall compound. I just mix up the color I want then go by a few of those cheap 50 cent paint brushes from the hardware store, it has to have bristles though. When I apply it I brush it on across the grain then go back over it and jab it down into the pores with the brush. If you use dry wall compound it dries fast so do small areas at a time. After it's been mashed in I will squeegee it off if it's the chemcraft stuff or leave it on and thick with the dry wall. The dry wall stuff sands so easy it's not a problem at all. The chemcraft clogs sandpaper like non other.

Also if you use chemcraft you have to wait a day before sanding and you can use burlap to pull off a good amount after squeegeeing off the excess just be careful not to pull it out of the pores.

Go on LMI's website, they have instructions on there written by the guy who taught me how to pore fill. It also helps to spray a coat of sealer on. I just spray a thin coat of sanding sealer then fill the pores.

Maybe you are pushing to hard with a squeegee and pulling out the filler. Which direction are you pulling the squeegee? If you pull it with the grain you are more likely to pull more of it out. I usually pull at a 45 degree angle to the grain and always burlap across it, never with the grain.

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  • 2 weeks later...

Thanks for the feedback guys.

I did a test run with sealing it first, filling, sealing again, and it went much quicker.

BUT

I am afraid of the sealer shrinking back into the pores. That was the main problem i had. ON some past guitars, i just sprayed finish and leveled it until it was flat and the pores were filled. Within 3 weeks the sealer had already sunk into the pores and looked terrible.

Does shellac shrink back?

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I use CA glue pretty much all the time now and have for years...but you probably already know that.

No matter what type of filler you decide on, what I'm curious of is what kind of backer you're using to sand your filler back.

If you're doing flat topped guitars (guessing, don't know for sure), then as long as you use a really hard piece of wood like a chunk of Rosewood, maybe Maple, something like that to back your sandpaper on, it shouldn't matter if your filler is harder than the wood.

I level super-soft spalt that's been filled with CA glue that way, so I certainly know about the hard filler/soft wood syndrome, but a very rigid, dead flat, and unyielding backer woodblock usually does the trick, and if there are any inconsistencies left, they're usually very minor and addressed in the finish process.

And if it's close but not quite, try either a larger sanding block or a finer grade of sandpaper, or both.

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Drak! You live!

I was hoping you would reply to this.

I use a hard rubber block for all of my sanding.

The biggest problem i had when using CA and expoxy was that within 2 or 3 swipes, the paper is clogged. Same with the timbermate. Its the worst wtih anything less than 220 paper.

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  • 2 months later...

I tend to leave a little above the surface (usually epoxy, but have done shellac and CA). Using a good scraper will take care of most of the excess, then I just sand like normal. A #80 cabinet scraper is great for making sure you don't dig in too much in any one place too badly.

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  • 4 weeks later...

I have used a razor blade many times. That is what i started out with about 5 years ago when i first started getting into this.

It still pulls it out of the grain.

Epoxy isnt as bad because it goes on thicker and above the surface. But it is hard to get smooth, unless you use a long cure epoxy.

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  • 3 weeks later...

I've had no problems with CA glue. But you definitely need to spread it as thin as you can before it cures (single coat works for me). Since it has very thin viscosity, it penetrates every single pore. I wait over night before the sanding, otherwise it builds up on the sand paper much more quickly and it may not cure as hard, depending on the CA brand. Result is very hard and very smooth surface. But it is very bad for your lungs and eyes.

I will also try polyester resin next time (the resin they use to make fiberglass products). I believe Warmoth use polyester as a pore filler too.

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On solid colors I've used exterior grade spackle paste with great results. It dries fast, sands easily, and shrinks very little. Although I've never added pigment to it, I've heard of it being done with good results. I follow the spackle with lacquer primer thinned about 4:1. This penetrates well, and binds and hardens the filler. Afterwards it levels out quickly. My favorite topcoat for a solid finish is http://pc.dupont.com/dpc/en/US/html/visitor/common/pdfs/b/product/nsn/Nason/496-00.pdf It's a 2 part urethane designed for spot repairs. It will cover just about anything without reacting, and the finish product is remarkable.

On clear or natural finishes I've used shellac, or nitro and sanded back. It always seems like a laborious never ending project, and I really work hard for what I think are mediocre results. I struggle more with the finish stage than any other part of the construction. I see that many are using epoxy products. Has anyone tried using casting resin?

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