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  #1  
Old 01-02-2022, 09:47 PM
rccosta rccosta is offline
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Default Finishing & Finishing Prep - Bastogne Walnut?

We're about to start the finishing prep and finishing stages of an acoustic guitar build using a fairly porous bastogne walnut. Our intention is to finish with a 2lb cut french polish.

Is there a way to pore fill without pumice? Could we just sand while french polish was freshly applied to get some dust in the pores?

Or could we just apply 4-5 coats of french polish and then sand back to a level surface as the pore filling process?

Your thoughts are appreciated.
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  #2  
Old 01-03-2022, 03:15 AM
nikpearson nikpearson is offline
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Default To fill or not to fill…

Walnut species do have significant pores which will be very visible if not filled, but some prefer the more natural look of the wood when the pores remain.

You’ll struggle to pore fill with just shellac; the pores a relatively deep and the shellac will only lay down very thin coats. Using pumice to pore fill is time-consuming but not as much so as just using shellac.

On my last build I employed Z-Poxy finishing resin as a pore fill on Indian rosewood. It was quite successful and certainly quicker than using pumice, but required quite a lot of sanding back and three coats of epoxy to achieve a flat finish, and it still wasn’t perfect.

As to shellac recipes: 2-pound cut is ideal, you can use it neat or dilute further with additional alcohol as you progress.

Good luck with then finishing.
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  #3  
Old 01-03-2022, 07:50 AM
redir redir is offline
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As mentioned it will take forever to just use shellac. If you do go that rout then use a brush and brush it on heavy. But I would highly recommend you don't do that. It's not only a waste of shellac but will literally take weeks.

There are lots of ways to pore fill out there now. On the last few I have used a pore fill product called Aqua Coat and it's fantastic stuff. Very fast, can be dyed, or dries clear and so on.

I have used CA to pore fill too and that works fantastic. You simply drizzle on the CA and squeegee it off with a paper towel. Dries fast. But you need proper ventilation for that method.

The two old school methods I have used is pumice and egg whites. Pumice is the traditional method that takes a lot of work but does a great job. Brush on a few coats of shellac and then with your FP pad sprinkle some pumice on paper then touch the pad to it picking some up. Drop several drops of alcohol on the pad to clear the pumice and what you have essentially done is made a sanding pad. The pumice tears fibers of wood and the alcohol and shellac glue them into the pores. A big mistake is in thinking you are filling the pores with pumice.

Egg whites are just that, the whites of the egg. Put a couple egg whites in a bowl, dip a piece of 320 grit paper in it and sand up a slurry of egg white and saw dust to pack in the pores. It dries very hard in short time. Then you sand back and do it again as necessary. It works surprisingly well.

There is of course traditional oil based fillers too. The only problem with those is they take a while to dry and they will stain the wood too but that is generally acceptable.

I only used epoxy once and I hated it but many do.

In the end though the point of pore filling regardless of what you use is to fill the pores so that your top coats are smooth. When you fill the pores imho you should always sand back to wood leaving only the pores filled before you move on to top coats. Some who use epoxy leave a layer of epoxy on as the base coat, not just filling the pores but an entire coat. I don't like that idea. I am one of those who thinks epoxy is good for boats and that is about it But many do and it seems to work for them.
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Old 01-03-2022, 10:44 AM
rccosta rccosta is offline
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Thanks for the comments and suggestions. What do you think about lightly sanding the french polish with 220 grit immediately after it's been applied? Could this be done to help push saw dust into the pores and lock it up before the next application?
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  #5  
Old 01-03-2022, 12:27 PM
BradHall BradHall is offline
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Egg whites are cheap, easy to use and clean up, and work very well on large pore woods like walnut and rosewood. I’ve also used the water based pore filler from LMI and like it even better.
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  #6  
Old 01-03-2022, 04:10 PM
Fathand Fathand is offline
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Quote:
Originally Posted by rccosta View Post
We're about to start the finishing prep and finishing stages of an acoustic guitar build using a fairly porous bastogne walnut. Our intention is to finish with a 2lb cut french polish.

Is there a way to pore fill without pumice? Could we just sand while french polish was freshly applied to get some dust in the pores?

Or could we just apply 4-5 coats of french polish and then sand back to a level surface as the pore filling process?

Your thoughts are appreciated.
I tried lots of shellac then sanding back with 600. I had bad luck with it. I tried applying with a pad and spraying it on with a Preval and aerosol can. By the time I got it thick enough that I didn't sand through, it was too thick to harden after several months, yes the shellac was fresh. Finally stripped it all of and finished with Tru oil.
3 tries on the top and 2 tries on the back and sides wasted.

If you really want a FP, I would suggest learning to do it the traditional way before looking for shortcuts.
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Old 01-04-2022, 07:52 AM
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Craig Wilson Craig Wilson is offline
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Fathand is right. French polish doesn't lend itself to shortcuts.

When I learned to french polish I was taught to pore fill with the same pumice and shellac method described by redir in post #3.

I like a 50/50 blend of FFFF and FFF pumice and a larger fad (golf ball size) with coarser cover (cotton terry cloth) for the pore filling. I tint the pumice a little with black or brown dry pigment to make sure the pores stay at least as dark as the wood.

I've tried other methods, but always end up coming back to pumice. I'm going to spend 20+ hours on the FP finish, so I'm not going to risk it by trying to save an hour on the pore fill.
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  #8  
Old 01-05-2022, 01:22 AM
Simon Fay Simon Fay is offline
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There are things that work and things that don't. I strongly advise to not take shortcuts.

By far your best and easiest solution is to use a "pore-filler". The Cardinal oil product is nice. Personally, I advise to use epoxy. It works incredibly well as a pore filler and is what I choose to use when I French Polish.

If using epoxy, use west Systems 105 resin with 207 clear hardener - don't use other brands.

For a traditional approach, use pumice but like French Polish, there is a learning curve.

Again, I strongly advise you to choose one of the methods above. IF you want to try epoxy, feel free to give me a call (bottom of website) and I'll walk you through the process.
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  #9  
Old 01-13-2022, 02:19 PM
rccosta rccosta is offline
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Update: I decided to try pore filling using a healthy amount (beyond counting "drops" but not enough to really be runny... think about 1/3 to 1/2 of a small pipette/dropper worth) of 2lb-cut french polish and immediately sanding with wet-dry 600 grit sandpaper with moderate pressure.

I "wet sanded" until I could feel the polish begin to gum up in the sand paper, at which point I stopped and moved on to another area. I repeated this until the entire back was covered. At this point, I then let dry for about 30 minutes, then did it all over again. I repeated this process until I started to see buildup of polish on the back in one or more regions -- it looked REALLY ugly.

It's remarkable how well it filled the pores, though! I'll update later with photos, but that almost perfectly filled the pores. Only in some regions where I was still "learning" my new method did it not fill perfectly. I'm about 30-40 layers of shellac beyond that and I'm nearing the point of a perfectly glasslike surface.

Proof will be in the pictures, but just thought I'd update.
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