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Does anyone prefer pumice for pore filling or a premix pore filler available form LMI or Stew Mac? Is there a benefit? Thanks!

Zpoxy is my preferred pore filler now. I've tried the others, but I really like the idea of filling the pores with a rock hard epoxy before spraying.

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Rob Flindall
Flindall Guitars
http://www.flindallguitars.com
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Steve, That's quite a question for around here. you'll get a lot of different answers.
I would say if you know how to fill with pumice and shellac then that's your answer.
if not a pre-made filler may be easier.
I've been using egg whites sanded into the pores myself.
you'll find answers varying form pumice, egg-whites, CA, epoxy, water based fillers to the pore-o-pac stuff and I've probably left some stuff out. Everybody seems to have different experiences with each.
As long as your using a pore filler that's non shrinking over time you should be good assuming you get the pores filled.

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Jim Watts
http://jameswattsguitars.com

Thanks, Jim.

I should have mentioned that this is my first build. I may have read somewhere that the pumice adds some depth or sparkle to the finish as opposed to the opaque pore fillers. Do you have any experience or opinion about that?

Thanks, Rob.

I bought both pumice and med brown and dark brown pore filler from LMI. Trying to decide before I start pore filling tomorrow. This is my first build, so I have zero experience with French polishing, though I have a furniture building past.

On a small instrument like I build i can make quick work with pumice. The problem is I don't really like the look. When you fill the pores with a material that is roughly the same color as the surrounding wood you lose a look of depth that epoxy gives you. Pumice filled looks very factory finished to me.

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Michael F Smith
Goat Rock Ukulele
http://goatrockukulele.com

I assume you checked out Todd's video on filling with zpoxy. Very informative.

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Under Compensated Nut!

I use Timbermate in a color darker than the wood. Usually black or black/brown. I think I'll try Z-poxy on the next one since I've heard such good things about it. Never tried pumice so I can't comment.

I've tried pumice and didn't have real good luck with it. I know a lot of people use it so I probably didn't do it correctly.

I've used the Zpoxy several times and it does do a nice job but I wanted something that was just less hassle to work with. I tried the Timbermate on the size 0 that I just finished and liked it. I'll probably use the Timbermate for my next one. Like Gil said, use a darker color.

Who knows, someday I may go back to the Zpoxy.

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Steve Smith
"Music is what feelings sound like"

I agree with you guys reference the Timbermate - by using a darker colour than the wood, it creates extra depth to the guitar. Using a similar colour to the wood seems to muddy the look.

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Rob Flindall
Flindall Guitars
http://www.flindallguitars.com
https://www.facebook.com/FlindallGuitars

Pumice is much much slower than paste filler.

Paste filler is the traditional filler for steel strings. It is much faster.

Pumice/shellac is semi transparent. Paste is not. The look is completely different. This makes a big difference with light or medium colored woods with lots of chatoyance. For rosewood, it doesn't matter much at all. I would go for the paste. It is solid, fast, proven, & no shrinkage.

Since you have already put on sealer coats of shellac, it is too late for Zpoxy.

I have not tried this newfangled 'Timbermate' stuff, but if my prior experiences with PVA based fillers has any bearing, I will steer well clear of it.

RE color: +1 definitely err on the side of darker

Why? Is there a problem putting a sealer coat on first and use Zpoxy later?

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Pumice is better suited as an abrasive , as a pore filler it takes forever to break down the minute particles of e.g. rosewood when mixed with shellac. Unless you like/desire all that excersise. Iprefer the gym and either a fast water based pore filler e.g hydrocote paste filler .Or behlens oil based filler which can be tinted to many oil based colours. an advantage if that is your goal.

There have been many reports of adhesion problems if you do that. Shellac sticks to Zpoxy, but Zpoxy doesn't adhere well to shellac.

Both traditional oil paste filler and LMI acrylic/microbead filler work fine over shellac, IME. Make sure to thin them, with naptha or water, respectively.

I usually just use shellac as a pore filler, it doesn't have to completely fill the pores, just seal them. The hand rubbed TruOil completes filling the pores, two or three coats is all it takes if the pores are completely sealed. I put on so many coats of oil anyway filling the pores is almost a moot point. I have used thin CA to fill pores on bloodwood, and it worked really nicely. That's what I'd use if my final finish was not going to be an oil varnish.

Be aware that your furniture finishing experience may be of little value, guitars are a lot different. I thought I knew quite a bit about finishing when I started building guitars, I painted custom motorcycles back in the 60s and I've built quite a few pieces of furniture, so I had a lot of other finishing experience.

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A man hears what he wants to hear, and disreguards the rest. Paul Simon

Takes me about 40 minutes, over 2 or 3 sessions. Perhaps 1 hour if it's not going so well.
In the Classical Guitar world it's a very common method. Paste filler is much quicker but usually requires a lot of rubbing back.

What grade of pumice are you using? The really fine stuff from LMI takes me forever (and a ton of alcohol) to work up much of a slurry, and pretty much quits working once the wood surface gets smoothed out. Maybe I just need to sand the surface with paper to rough it back up if that happens before all the pores are filled, to give the pumice more texture to work with. I usually start from a scraped surface, so pretty smooth to begin with.

I also need to try using sandpaper to make the slurry, and switch to cloth pad to shove it around and into the pores, because another of my main problems with pumice filling is that the pumice abrades the pad faster than it does the wood. Wet/dry sandpaper ought to be more durable. Hopefully it won't shed blue abrasive particles when exposed to alcohol...

I use 3/0. The thing with pumice is that it becomes finer the more you work it.
I doubt it's the surface that you are having problems with, more the technique. The very first time that I tried the pumice technique I filled a Back in less than 15 minutes. There wasn't an unfilled pore to be seen. It was a breeze.
Unfortunately my new found confidence didn't last too long. The very next time I tried to pore fill with pumice it was nothing short of a nightmare. It just didn't happen, try as might. I kind of gave up and used other types of filler but I did continue to try pumice on scraps. Eventually I got the technique back.
My best advice is side light. You really do need to see what is happening whilst you are using the pumice. Strong side light and looking at the surface at an oblique angle helps. Work very small areas at any one time, say 3 x 3 inch. Don't be tempted to move on until you've inspected that area and the pores appear filled. It's easy to grind the pumice, moving over the entire surface thinking that you are filling pores.
Too much pumice and too much shellac on the surface just results in a sticky substance that you pull out of the pores. It's probably best to err on the side of less when laying down the initial coats of shellac. Same with the pumice. You can always add more if you feel that either substance is lacking. Experiment with the amount of pressure that you are exerting with the pad. Try very light pressure. Inspect the area. If it's not filling try increasing the pressure a touch. Look at the surface of the pad. That should tell you how things are going. If it's going well the pad will wear out very quickly. Holes appear like they are back in fashion.
It will sink back a touch after a few days or so. That's when I go over the surface again, although the second time is much quicker.

dennis haven/t tried it yet but I read in a fine woodwork article of woodworkers using drywall compound from hdware store to fill the pores of open pored woods.Don/t know how it would work on gtrs.It/s mixed with water and then one can tint it with an oil based colour/e.g, minwax and then topcoat with shellac /varnish/laquer etc. Thanks for thepumice/shellac tutorial michael. I watched an english luthier using the pumice/ shellac method for pore filling. I have yet to try it.I/ve done waterbase and it drys too quickly for my taste plus I don/t care for the look .Behlens oil based paste filler looks promising. I/ve done a lot of it in the past with furniture. But guitars are far different, I/ve also done an epoxy pore fill on a very open grained locust neck.I like the way it fills the large open pores.topcoated with varnish

If you use a colored oil-based filler, often called a "paste" wood filler, be sure to seal the wood with shellac or another sealer first, or the pigment in the filler will color the wood, often in a way that isn't particularly nice. I suspect this is true of colored water-based fillers. (I haven't tried the Timbermate I have, so I'm not sure how it works in this regard.) This brings up the archetypical finishing advice: try it on scrap first. And not just the filler, but the whole finishing schedule you have. It can save a LOT of time, not to mention wailing and gnashing of teeth.

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Tim Allen
"Never hurry, never rest."

I have not seen it mentioned so I will add LMI Micro-Beads filler to the mix.
After trying all of the above, I have settled on this as my go-to, using a much darker color than the wood to pop the grain.
I don't seal first, just rub it in scrape it off, all good - no issues with coloring the wood or shrink-back...

Rob

I'm using wall fillers tinted to the color of the wood for grain filling. Not the best but it does the job, and is readily available. Problem with pumice/shellac is you can't dry sand shellac at all. The moment you try and sand shellac it gums up any type of sandpaper, making them absolutely useless.

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

I've never had that problem, shellac dry sands just fine for me. I do let it dry at least 24 hours before sanding.

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A man hears what he wants to hear, and disreguards the rest. Paul Simon

Lots of writers say to scuff sand shellac after 1 hr with 400 grit and start your topcoat. It probably gums up quickly I/m guessing in taiwan because of the high humidity, or your shellac could be too old ??? shellac is vy humidity sensitive 45% is ideal IMHO. Like you roger I just put 2 coats of shellac as a sealer on a tenor uke under the varnish finish. I did 2 vy thin coats 1 hr apart and waited 24 hrs to scuff sand worked perfectly but humidity in my bsmt is abt 25% at 58 deg F. FP is also vy sensitive to the weather . Ps shellac tip , I now store mine in the fridge at 40 deg F keeps way longer.

I guess it also explains why I kept having so much trouble doing FP...

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com