Pittsburghin - Posted - 04/15/2013:  11:49:35

I have a mahogany project I'm about to finish...I'm going to pore fill, then sand down with 320 and then use tru oil in coats....what type of surface prep should I be doing prior to the pore filling?  Should I apply a base coat of Shellac/alcohol first?  Thanks.

Old Hickory - Posted - 04/15/2013:  12:16:51

I've done one mahogany neck and resonator with Tru-Oil and I I did apply a coat of Zinsser Bullseye Sealcoat (maybe 2) to prevent the wood from being stained by the black pore filler. Sealcoat is dewaxed shellac and is marketed by Zinsser as a "universal sealant." It goes both over and under anything.  I filed the pores with drywall compound dyed black.

Assuming the neck or resonator you are finishing are already bound, you'll want to give the binding extra protection against being stained. So you could use an artist's brush to brush on additional Sealcoat right on the binding.  You'll sand that smooth before doing the Tru-Oil. This coat can reduce the amount of scraping you'd otherwise have to do to get the pore-filler color off the binding.

Heel of neck - done

Resonator almost done2 - about 30 coats of Tru-Oil

sunburst - Posted - 04/15/2013:  12:20:43

you can seal first, but you don't have to. What filler are you using? Is it clear or does it have stain or dye in it? If you have a dark colored sealer and you want it to act as a stain for the wood, you might not want to shellac seal first. If you are using a clear pore filler, sealing with shellac is optional. Either way, sealing first might save a little material because less pore filler may soak into the wood.
I might suggest some scrap mahogany, sanded to 220 (320 is overkill) and then try the pore filler and TO with and without sealing first, and see which you like better.

OldPappy - Posted - 04/15/2013:  12:29:30

Old Hickory,

I opened this thread after seeing the title because I have used Bircwood Casey Tru-Oil for more years than I like to count, and figured I might could add something, but see you have answered the question already.

I use the Bullseye sealcoat too. It is easy, and it works great.

However I neever would have thought about using drywall compound dyed black for a filler.

The grain on that resonator sure looks good, so I see what it does with Mohogany.

I am wondering what it might do to enhance the stripe in curly maple.

OldPappy - Posted - 04/15/2013:  12:33:12

John,

Notice that Old Hickory stated "to prevent the wood from being stained by the black pore filler".

Looking at that resonator I see what he was after, and think it is beautiful.

Quickstep192 - Posted - 04/15/2013:  12:47:56

quote:

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Originally posted by Old Hickory

 

I've done one mahogany neck and resonator with Tru-Oil and I I did apply a coat of Zinsser Bullseye Sealcoat (maybe 2) to prevent the wood from being stained by the black pore filler. Sealcoat is dewaxed shellac and is marketed by Zinsser as a "universal sealant." It goes both over and under anything.  I filed the pores with drywall compound dyed black.

Assuming the neck or resonator you are finishing are already bound, you'll want to give the binding extra protection against being stained. So you could use an artist's brush to brush on additional Sealcoat right on the binding.  You'll sand that smooth before doing the Tru-Oil. This coat can reduce the amount of scraping you'd otherwise have to do to get the pore-filler color off the binding.

---

That resonator is stunning. 30 coats! WoW! How long did you allow for drying between coats?

Old Hickory - Posted - 04/15/2013:  12:54:42

quote:

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Originally posted by OldPappy

Notice that Old Hickory stated "to prevent the wood from being stained by the black pore filler".

Looking at that resonator I see what he was after, and think it is beautiful.

---

Andy:

Thanks for the compliment and thanks for pointing out my reason for sealing the wood.

My reason for black pore filler was to emphasize the grain. If I did not want to do that, I would have filled with something clear or something the same color as the field wood -- or would have gone straight to Tru-Oil and sanding to fill the pores with a slurry of Tru-Oil and mahogany sanding dust. That produces a nice result, too. But I was hoping to make the pores dark. The pores in the resonator are a bit darker than they appear in the photo.  My photo lighting skills are not the best.

My limited experience with Tru-Oil on mahogany is that if you don't fill the pores first, it can take many, many coats for Tru-Oil to fill the pores up to a level surface. Of course, some people like a little bit of unfilled grain to remain in their work.  I think I sanded out some of the pore filler after two coats. Probably should have done one additional coat on the resonator.  BUt I was impatient.

This Youtube video is where I got the idea about using drywall compound as pore filler 

Old Hickory - Posted - 04/15/2013:  13:17:30

quote:

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Originally posted by Quickstep19

That resonator is stunning. 30 coats! WoW! How long did you allow for drying between coats? 

---

Thank you so much.

I probably allowed a minimum of 3 hours between coats, which I think is in line with the manufacturer's directions.  I work at home, so I was doing 3 or 4 coats a day. Generally one in the morning, one in the afternoon and one in the evening. Sometimes one more late at night.  I sanded after every third coat with 320 to fight build-up and try to keep the surface level. It was during all this that I noticed that the pores weren't filled all the way. That's why this took so many coats.

Tru-Oil is very thin. But it has polymers (resins) in it, which means it is essentially a wiping varnish. That means it does build a film finish, unlike a plain or true oil. Not only does it build a film, but it can be buffed or polished.  I think I used 3M Scratch Remover followed by Meguiars #10.

But because it is oil-based, it imparts an amber cast.  My binding does not look very white.  I'm thinking of sanding back to try to get rid of some of the amber then freshening the surface and polishing one more time.

Where in Maryland are you?  My bluegrass band is playing in outer Silver Spring next Thursday.

Edited by - Old Hickory on 04/15/2013 13:18:23

grm405 - Posted - 04/15/2013:  13:21:42

I have finished 4 necks, 2 pots and a resonator with Tru-oil.  Both pots and a neck were maple, the rest mahogany.  You can achieve a smooth finish without filling even on mahogany, but it takes a little more time.  The grain on the maple internal resonator pot is just staining (yellow followed by fruitwood and then a diluted dark hickory stain).  Quite dramatic and it is all the staining.  Keep in mind that Tru-oil tends to add a brown cast to the finish, so the final finish will be browner than the stained raw surface.

A gloss finish is possible, as seen (and those are before rubbing out).  The secret to "smooth" is 4-6 coats in a day, followed by careful sanding to smooth/level things, then repeating the process several times.  The final finish is several very thin coats buffed on and let dry for several days at least.  Then rubbing with a fine compound.

Tru-oil is very durable and hard after a week or so.  Fairly tender before that.

Gerry

That is a coordinator rod, not a dowel stick

Resonator finished with Tru-oil

scooter46 - Posted - 04/15/2013:  13:28:24

I used the drywall patch compound and it worked great I didn't use any stain, just thinned it out real good and rubbed it on once it dried it sanded down real easy, then put on truoil.

OldPappy - Posted - 04/15/2013:  13:37:36

One thing I do after the final coat of Tru-Oil dries, is cut it back one more time with 0000 steel wool. At the same time the steel wool can be used to remove the finish from the binding.

Using 0000 steel wool as an applicator pad I then apply a good coat of paste wax (have used Minwax, and Johnson's floor wax to same result). Rub this in good, let it haze over, and then buff. I buff it by hand with a soft cloth.

This makes the neck so slick you will have trouble holding on to it, but will like the way your had will slide on that neck when you are playing the banjo.

Unless you like the sticky feel of some finishes.

If you have ever "spit shined" your shoes in the service, you may even know a few tricks to make that wax really shine.

Pittsburghin - Posted - 04/15/2013:  20:00:29

I broke down and bought actual grain filler, medium color. I had concerns about dying the drywall compound, since I've never used it, etc. I'm using por-o-PAC brand filler.