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Pore filling acoustic guitar

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Forum topic by 12bar posted 05-01-2017 02:10 AM 632 views 0 times favorited 11 replies Add to Favorites Watch
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12bar

10 posts in 363 days


05-01-2017 02:10 AM

Topic tags/keywords: finishing sanding

I’m finishing my first acoustic guitar and have reached the pore filling point on the Indian Risewood back and sides. I will also be pore filling the Sitka spruce top and the mahogany neck. Not wanting to make things harder than they need to be I am doing some test pieces of each material and I am testing with Seal Lac and Aqua Coat as pore fillers and then sanding.
What I don’t understand is the wet sanding that I do after the pore fillers have dried. How do I know how far to sand them down. I have been sanding to far I think as when I finish there is no shine at all except for where for the pores that are shiny and below the surface. So could someone please tell me how much or how far I should be sanding.
I would appreciate any help regarding what I am doing.
After the pore filling is done I will be using Royal Lac ingarnet or super blond. Thanks
12bar


11 replies so far

View Rich's profile (online now)

Rich

1976 posts in 424 days


#1 posted 05-01-2017 04:34 AM

I think the subject of your post is the key. You’re filling pores. I have a lot of experience with Aqua Coat. In fact the first video I watched trying to learn about it was someone doing fill on a guitar body.

I’ll start off by saying that I have zero experience finishing guitars, or any other instrument. However, when I’m seeking that sort of piano finish, Aqua Coat works beautifully. I don’t believe you’re sanding too far. That’s pretty much what it looks like when you have completely filled the pores and sanded it smooth. Shiny fill and then the exposed wood.

I’m at a bit of a loss because I don’t know the whole finishing plan you have. However, if you were to topcoat the surface you have, you should have a level finish, free of pores.

You could go with various sanding sealers or other products that build up, and sanding them smooth, but not down to the wood, and rubbing them out. Aqua Coat is not one of them.

I hope this made some sense.

Edit: Why are you looking at shellac for a top coat? I love shellac, but was under the impression that lacquer was the usual topcoat for a guitar. Correct me if I’m wrong.

-- No matter how much you push the envelope, it'll still be stationery.

View Luthierman's profile

Luthierman

178 posts in 922 days


#2 posted 05-01-2017 11:28 AM

Okay, first congrats on the build. Wait until you play it!

I have never needed to pore fill the top whether it’s spruce, cedar, or redwood. For rosewood shellac will take you quite a bit of time to fill those holes. I made my own out of dust and finish or bought some from the various suppliers out there.

I always sand my guitars down to 320 by hand, always with the grain, then wipe them off with alcohol, and take them outside to let the sunshine show all the spots I missed. After that I start the French polish process with shellac. After about 20 coats I do my first wet sand. Rinse and repeat about a bazillion times as the coats are ultra thin. Thinner the coat the better the finish. If using shellac for the entire process you can only use alcohol to clean it before you have shellac on it as the alcohol melts shellac. Damp clean rags work well.

Edit: shellac will give you the best tone but it isn’t that durable in terms of wear. I finish all my guitars with shellac. It’s the best if you ask me. Big manufacturing plants don’t use it because of the time it takes.

-- Jesse, West Lafayette, Indiana

View johnstoneb's profile

johnstoneb

2634 posts in 2007 days


#3 posted 05-01-2017 12:22 PM

You are doing things correctly. Continue to apply finish and sand off until all the pores are filled and the entire surface is dull after sanding. The first few coats I will sand it almost all off. I start with 180 or 220 using that until the pores are almost all filled then I will star moving up in grits 320, 400. I usually wet sand with the 400 and higher.

-- Bruce, Boise, ID

View 12bar's profile

12bar

10 posts in 363 days


#4 posted 05-01-2017 02:58 PM

This is great to get these responses. Thank you all and let me answer a few of your questions.
First I am using Aqua Coat because it is an easy to apply and I believe doesn’t seem to leave any fumes. Same for Seal Lac. I have to work in my garage and the furnace and water heater are natural gas so I have to be careful to not cause an explosion.
After putting on Aqua Coat I will Seal it with Seal Lac . Then I will then start applying Royal Lac by French Polishing.
Many people spray nitrocellulose but I can’t. It has a nice gloss and it quite hard when cured. Shellac generally is used on high end classical guitars but as pointed out does not provide the hard surface that nitro does. Then here comes Seal Lac and Royal Lac which has been formulated to give you the advantages of shellac but when cured gives a harder finish than normal shellac. So I can apply it it either with brush or in a French Polishing method and it appears get the benefits on shellac and a better hardness than normal shellac.
Now let me see if I understand about the Aqua Coat. When I sand it down and I end up with shiny pores but generally bear wood that is how it should be. Then I don’t understand when I know how many times I do this. Do I just run my hand over the wood till I can not feel any differences in the smoothness of the wood? I guess the question really is now how do I know when I have completely filled the pores so I can move on to begin the Royal Lac.
BTW I did sand the complete body with 120, 220 and 320. I also did the same on my test boards before applying the Aqua Coat and the Seal Lac on different test boards.
One last question regarding pore filling the top on the guitar which is I thought I should pore fill since I will be putting Royal Lac on it. Am I incorrect about filling Sitka Spruce?
Thanks again for your help. 12bar

View Loren's profile

Loren

9610 posts in 3482 days


#5 posted 05-01-2017 03:18 PM

Spruce doesn’t need pore filling, just use
lacquer burn-in sticks to fill any gaps
between the binding and the soundboard.

View Luthierman's profile

Luthierman

178 posts in 922 days


#6 posted 05-01-2017 03:52 PM

Just a BTW here, I make my own shellac with ever clear and de-waxed shellac flakes. No odor at all. I am pretty sure you could drink it. It’s easily thinned or thickened too.

-- Jesse, West Lafayette, Indiana

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12bar

10 posts in 363 days


#7 posted 05-01-2017 04:00 PM



Just a BTW here, I make my own shellac with ever clear and de-waxed shellac flakes. No odor at all. I am pretty sure you could drink it. It s easily thinned or thickened too.

- Luthierman


I thought about getting the flakes and actually got a coffee grinder at the Goodwill to grind them. Then I started reading about Real Lac and watch a video of someone using it on a guitar with the French Polishing method after it was pore filled. He used alcohol but I decided to use Everclear like you. I don’t know yet if I will use walnut oil or something else but have to make that decision pretty soon. Any suggestions?

View Rich's profile (online now)

Rich

1976 posts in 424 days


#8 posted 05-01-2017 06:47 PM

I remember The Furniture Guys talking about using Everclear because it’s much better filtered than denatured alcohol and gives superior results.

I have to say that as one who possesses a tin ear, the fact that someone like Luthierman can distinguish the tones that different finishes provide is truly mind-boggling.

-- No matter how much you push the envelope, it'll still be stationery.

View johnstoneb's profile

johnstoneb

2634 posts in 2007 days


#9 posted 05-01-2017 07:21 PM

If you are doing a real french polish you don’t need to fill the pores. The first part of the french polish with the pumice fills everything.

-- Bruce, Boise, ID

View 12bar's profile

12bar

10 posts in 363 days


#10 posted 05-08-2017 09:08 PM

I’m filling the pores with Aqua Coat and then I’ll put Seal Lac over it. I bought a spray gun , the one the developer of the Seal Lac and Royal Lac recommended. I will seal all the guitarwithbit. I don’t know yet whether to brush the Seal Lac on to get a thicker coat or to spray it outside. Can’t spray in the garage with open games.
I’m wondering also about staining the neck. Is it best to use a water stain first and then put the Aqua Coat over it or do I mix the water stain in with the Aqua Coat?
One other question while working on fitting the ebony heal cap on yesterday I put a small ding in the Sitka Spruce. I know I shouldn’t try to sand it out but I am wondering if I can use a rag and a steam iron to try to get it out or do I try to fill it with something?
Thanks for any help.
12bar

View Planeman40's profile

Planeman40

1034 posts in 2595 days


#11 posted 05-10-2017 08:42 PM

I have been making my own shellac from shellac beads that appear to be right off the tree limb it was collected from. It still as bits of bugs and trash in it.. Shellac is a LOT cheaper this way and the hard shellac beads last for a long time on the shelf, unlike prepared shellac. Very simple to make. Pour the shellac beads into a jar, add some alcohol (gallon can from Lowes), let sit for a few hours. Stir and let sit, stir and let sit, until all of the shellac is dissolved. Better to mix it a tad thick, then thin it out as you need to. Get a 2nd jar to pour the shellac into, but not yet. Steal a pair of nylon stockings from the wife or girlfriend or buy some. Use SHARP scissors to cut the stockings into squares about 5” on a side. Using some typewriter paper, make a paper funnel by folding it in half, then turn it 90 degrees and fold in half again. Cut off the folded corner tip to make a hole about 3/8” dia. when the paper is unfolded. Use scissors to make the unfolded top edge of the funnel round if you want. Wad up the piece of stocking and stuff it into the hole so it won’t come loose. You now have a throw-away funnel to strain the shellac to remove the trash and bugs (note: it takes a very fine mesh to strain, commercial straining cloth is to coarse). Put the funnel into the mouth of the unused jar and carefully pour the shellac into the funnel. It often drains through the stocking mesh very slowly so be patient. When finished, close up the jar, throw the old jar out (or wash it out with alcohol), and throw away the funnel. Your shellac is ready to use.

-- Always remember: It is a mathematical certainty that half the people in this country are below average in intelligence!

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