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I used four coats of grain filler on a koa uke. Grain looked filled, but after a coat of sealer (using Colortone products from Stewmac), some pores are unfilled. When I dab on grain filler it appears that the pore is shucking the filler which leads me to believe I have some type of contamination going on. I sealed the uke with a dewaxed shellac (Zinnser) before I grain filled. I use gold 3M (non-stearate) sandpaper between coats. I also had a similar problem with a walnut uke that I did not prime with shellac. What am I doing wrong?

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A higher purpose for wood.
Rich Smith
Issaquah, WA

Why did you seal prior to grain filling. I suspect this is the issue. Typically you fill the pores prior to sealing the wood. This is extremely important when using an epoxy pore filler. Shellac will adhere over most any thing but some compounds will not adhere over shellac.

On the walnut with out sealing first I do not know what the problem is. I assume you are following the Color tone instructions. and I can not give much of an opinion or advice on that filler as I have not used it.

How are you spreading it? What are you spreading it with? Are you giving it the needed cure time? Most past type fillers go on heavy and when cured are burlapped off.

I went and read the instructions on this filler. Two things I noticed that were very important. The first is to be applied to bare wood sanded to 220. this is probably important to have the right tooth on the wood for the filler to adhere to. The other is filling with the grain and allowing 2-5 min. before excess clean up and do the excess clean up at a 45 degree angle to the grain. i would bet more than 5 min. would be even better but I can't say that for sure. Yes I know that is more than two things. Oh well You might try using unwrapped burlap rope in lue of cloth to wipe off the excess after drying. the burlap acts similar to steel wool and actually cuts the filler off instead of dragging it off.

Why would anyone not pore fill with epoxy these days unless you're going for a particular color that you get with traditional pore fillers or doing some in the wood stains?

Hey Hesh good to hear from you.I`ve had that same experience putting lids on paint cans many times.Ricardo, next time pore fill first.
                    James

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James W Bolan
Nashville Tennessee

I have had issues with z-poxy coloring my mahogany necks so dark that they almost look black. To adjust for this, I have started wiping a very weak shellac solution (maybe a 1/4 pound cut?) over the mahogany prior to pore filling with zpoxy. I have been using an old t-shirt to wipe on the shellac and only using just enough so that the wood is barely moistened. This is not enough to completely seal the wood, but it does seem to help with zpoxy staining the wood so dark.

The results are great so far and the necks retain their original mahogany color and the pores are filled properly.

 

 

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Reguards,

Ken H

It does sound like the problem is the pore filler (unless the sealing coat
you put on prior to the filler was too thick - should be very thin). I use the
pore filler that LMI sells and it works very well. I spray a light sealer coat
before filling so that the filler doesn't stain the raw wood.

As for epoxy, I simply do not like the look of a base coat of epoxy over
the wood grain. It's "plastic-y" looking to me and when I use epoxy as a
pore fill, I sand it back to bare wood, very carefully, leaving the pores
filled. Very tedious, but that way, I get the look of the wood finished with
just the lacquer. And it requires the silica filler or it's like sanding vinyl
upholstery. So, as you can tell, I'm not enthused about the epoxy pore
filling. I use it because sometimes it works better (on very dark wood with
very open grain - think Wenge, it looks a little better than the dark-
stained pore filler), but it's much more time consuming than the paste
pore filler (more expensive, too).

sure Hesh .. the brown spots were pore filler .. well, of a different nature is likely closer to the truth, but come to think of it, we dont want to know ...

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

We're using West Systems epoxy, and I have none of the issues mentioned here by Crazytooguy.

(and it would be really nice to have real names here instead of what I consider inane handles...)

Just call him Pat.  That's his name.  Sometimes it only takes a quick look.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

I have not been happy with Colortone grain filler.  I will try the z-poxy next time.  As Ken says I will put on a sealer coat so that the grain filler doesn't change the color of the wood. 

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A higher purpose for wood.
Rich Smith
Issaquah, WA

I think there was a push to institute a real-name policy here at some point not so long ago, I also appreciate that sort of thing.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I have use Zpoxy for several years on Mahogany. Not one time have I had an issue with it coloring any wood more than the tint of the hardener which is a clear pale amber. I am not disputing you but I cant see how this is happening. The epoxy goes on clear with a slight amber hue, dries clear with that same slight amber hue

If I left the Zpoxy on the body at full strength I too would get a plastic look, but I sand back to the wood and leave the epoxy only in the pores. Then make up a very thin batch of epoxy with a 60% alcohol and 40% epoxy ratio and lightly rag that on just to color the wood evenly. There is no real film thickness to this therefore the plastic look is not there. I think that most that don't like the look of epoxy filler never remove the film thickness left by the pore fill down to the wood and that is when you get the plastic look.

Yeah, my name is Pat, but I don't know how I can change my login. The "Edit
Profile" allows you to change everything except the user name. I'll gladly edit
it to my name, if someone would be so kind as to tell me how.

Michael, I haven't tried your method, but it does sound like it would avoid
the coloration. It is that amber tint I don't like. BTW, I've been using System
3 epoxy. Maybe some of the other brands have less of that amber hue to
them. I do like the clear pore fill, which is why I use it on very dark woods.

You don't need to do that, just put a signature at the bottom of your posts.  My name, Waddy, and my little saying are in my signature block.  When you edit your profile, add you name in text, and it will print at the bottom of each post.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

One other issue I might mention here and I guess you have not had a problem yet, but you may later down the road. That is that Zpoxy or any epoxy for that mater does not adhere well at all over shellac. Maybe the surface tension cause by the pore it's self is enough to hold it in the pores for you but the process of applying shellac first then Zpoxy over it, I could never recommend to anyone. Just do a test on glass. Apply shellac and allow to cure. Then apply epoxy over the shellac. Once cured the epoxy will peel right off the shellac.

I must speak up here. Maybe some are having success with apply a light shellac sealer prior to zpoxy filling. But I fear the success will be fleeting. epoxy does not adhere well at all over shellac. I can't invasive this enough. When you sand back the epoxy to the wood after cure leaving the epoxy only in the pores. You run a high risk of pulling the epoxy out of the pores if shellac settled in the pores. If you are going to use shellac first you might as well use matching wood dust and shellac to fill with Robbie Obrien has a great segment on pore filling this way on his finishing DVD

I know this sounds like I am on a some sort of a campaign here but it is true. Epoxy does not adhere to shellac!!!!!!!!

Now shellac will adhere well to lightly toothed epoxy but not the other way around.

I must speak up here. Maybe some are having success with applying a light shellac sealer prior to zpoxy filling. But I fear the success will be fleeting. epoxy does not adhere well at all over shellac. I can't express this load enough. When you sand back the epoxy to the wood after cure leaving the epoxy only in the pores. You run a high risk of pulling the epoxy out of the pores if shellac settled in the pores. If you are going to use shellac first you might as well use matching wood dust and shellac to fill with Robbie O'Brien has a great segment on pore filling this way on his finishing DVD

I know this sounds like I am on a some sort of a campaign here but it is true. Epoxy does not adhere to shellac!!!!!!!!

Now shellac will adhere well to lightly toothed epoxy but not the other way around.

West Systems epoxy is water-clear; use it directly on the wood; don't seal first; don't thin it; exact same wetting properties as the McFadden sealer I use. No problem.

Why so hard? Why all the problems when the solutions are right out there?   Why the resistance to what actually works?

Rick, Is the west systems eposy available at the west boating stores?

I'll have to give this a try to see if it helps. The only thing I dont like about zpoxy is the color of it.

Michael, As far as the shellac, dont have a coronary over it. As I said, the solution I am using is so weak that it barely leaves any on the wood anyway. I am just giving it a quick wipe with this extremely weak solution. I always give 3 coats of z-poxy anyway, and sand back to bare wood every time. The system I am using is working fine and it is keeping the z-poxy from darkening the mahogany. I might add that the only place I am using this is on the necks. For some reason the end grain around the heel is the place where the darkening was taking place. My system cures that problem.

I'll give the west systems epoxy a go and see how it does.. thanks for the tip!

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Reguards,

Ken H

I really like the pump set you can buy for west systems epoxy. One full pump from each resin and hardener and you get a perfect 5-1 ratio everytime, makes things so nice and easy. Also I really like how thin it was compared to epoxy I had used in the past for other things and how crystal clear it is, won't bother with anything else now. Found the stuff at my local rockler by surprise. Jason

West Systems is made by the Gougeon Brothers, the guys who really put epoxy on the map in high tech ice boat and racing yacht construction. WEST stands for Wood Epoxy Saturation Technique, and it's part of the whole "cold molded" hull thing where they build up layers of cross grain thin wood on a wooden frame work that is not part of the boat. These guys are the epoxy kings, and their products have been tested under conditions that make our guitar making issues look positively quaint. This stuff makes killer pore filler, and it looks to me like it's saving me a day in the spray booth and three coats of polyester and a whole cycle of sanding and leveling. I can go from epoxy fill, to sanding, to sealer, to a quick scuff, to top coating, to sand'n'buff.   No UV, three days in the booth, preferably two days of cure, and out the door.