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so. i almost finished my first guitar... i have to apply only the shellac. i have read tones and tones of french polish method. about pumice or 3 pound cut shellac, commercial pore filler etc.. but i heard someone talking about pore filling with sand paper. does anyone knows how to do that?

Once you sand up the dust it's got to be held into the pores some how. With pumice you use shellac as the binder. I don't think that would work very well with sand paper. FWIW I like to use egg whites. Using egg whites with sand paper you make an egg and saw dust slurry that fills in the pores. It hardens up real well in short time. But in any case I don't see how you could just use sand paper without some sort of binder.

As jfmckenna says any sanding/abrading technique is going to require a binder. Pumice uses alcohol to soften the spit coats of shellac and binds the sawdust and pumice. You probably heard about this sandpaper technique as it relates to oil finishes. Much like the egg white approach above, some have wet sanded with an oil finish (like tru-oil) to form a slurry of dust and finish that gets packed into the pores and hardens there. I have not done it but a search for "tru-oil" and "slurry" may get you the information you are looking for.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

Yes you sand the wood using Egg White or Tru Oil as the binder. The slurry fills the pores. Obviously you can't sand over any inlays otherwise you will badly stain them. You can sand close to the inlays and push the slurry over them, filling the surrounding pores. Any inlays will need to be well sealed prior to the sand fill method.

thanks for your replies. You can pore fill the wood using sand paper and alcohol. I just did that..

You may have filled the pores, but without a binder such as shellac or egg white I would be concerned about them staying filled.

I'm going to make the assumption that you first did some wash coats of shellac, otherwise you would have dried sawdust in the pores and it won't stay. I curious how you delivered the alcohol when you used the sand paper. How did you avoid using too much. With the traditional pumice and alcohol technique the pad holds the alcohol as you abrade the surface with the pumice, keeping just enough available to soften the shellac without making a mess. I am always amazed at how little alcohol it takes. For me the pumice technique is surprisingly simple and effective. My only complaint is that it takes longer than I would like (though not unmanageable). If there is a faster way to get there with sand paper I'd like to hear more about it.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

the technique I used is the same with the pumice. i use sandpaper instead of pumice. i applied some washing coats. i think is faster than the pumice method because sand paper is more abrasive than the pumice. i used 1200 g sandpaper.

I'm still unclear on how you deliver the alcohol while sanding. Surly you don't just pour some on the surface and sand.?. Do you wet the parer; is that enough alcohol?

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

I use a small amount of alcohol dropped on the sand paper.

No binding agent makes me think that the sanding dust inside the pores will be pulled back out when you start applying the first few coats. Keep a close eye on the pores as you start and see if the sanding dust will stay in the pores. You might need to back up and try a different method with a binding agent. I am particularly fond of using dyed jointing compound (ala O'Brien) or Timbermate.