grain filling two different woods on the same body

Konquest · #1 03-15-2013, 10:19 PM

I am at the stage in my build where I am sanding the body and ready for grain filling in preparation for finish. The body is ash with a 1/4" spalted maple top, with a black accent veneer separating the two. Obviously the ash, being a porous wood, needs to be filled, and I plan on using the Timbermate filler, thinned and brushed on in as many steps as possible to fill the pores. Now where I am a bit confused is the spalted maple. Maple is not particularly porous but the spalted wood is spongy and will soak up a finish, so some kind of prep/filler will probably be necessary.

-Does anyone have experience using Epoxy filler or CA glue as a filler/hardener for spalted woods?

-If so, are there any particular brands or viscosities that I should use or stay away from? Are these any different from what I would get at Rockler for general woodworking use?

-Is there any foreseeable problem with filling the back/sides of the instrument with one product, and the top laminate with another?

-Should I apply some kind of sealer product to the top before squeegeeing CA glue across the top of it?

Bruce Johnson · #2 03-16-2013, 05:21 AM

I recommend using West Systems epoxy as the filler for both the ash and the spalted maple. It works very well for both of them. Use the 105 resin and either the 206 or 207 hardener. The West Systems dries hard and sands well, and is very stable long term. I have basses that I built 15 years ago, with ash bodies filled with West Systems, and there's no settling or shrinkage under the paint. I currently use it as the grain filler under water-based Target paint.

One warning: Polyester paints should not be used directly over epoxies like West Systems. Polyurethanes and water-based acrylic-polyurethanes are fine. If you are going to use polyester, you need to put on some base coats of polyurethane first.

tjclem · #3 03-16-2013, 06:09 AM

Quote:

Originally Posted by Bruce Johnson

I recommend using West Systems epoxy as the filler for both the ash and the spalted maple. It works very well for both of them. Use the 105 resin and either the 206 or 207 hardener. The West Systems dries hard and sands well, and is very stable long term. I have basses that I built 15 years ago, with ash bodies filled with West Systems, and there's no settling or shrinkage under the paint. I currently use it as the grain filler under water-based Target paint.

One warning: Polyester paints should not be used directly over epoxies like West Systems. Polyurethanes and water-based acrylic-polyurethanes are fine. If you are going to use polyester, you need to put on some base coats of polyurethane first.

I never fill my swamp as i like the feel of the wood but that is interesting that you have used that is filler. Something to think about..t

Konquest · #4 03-16-2013, 09:20 AM

I think it is settled at this point that I will use epoxy. I have a digital scale for getting the exact ratios of resin to hardener, and I can buy West Systems at woodcraft down the street.

Perhaps just to be safe, I should pad on a few light washcoats of dewaxed shellac over the epoxy? I don't want any adhesion problems. I plan on using either nitrocellulose lacuqer or a two-part automotive urethane as a clear coat.

JLS · #5 03-16-2013, 11:49 AM

Several years ago, Brian Burns gave a presentation on grainfilling, using odorless CA, and a credit card squeegee.

Bruce Johnson · #6 03-16-2013, 05:27 PM

Quote:

Originally Posted by Konquest

I think it is settled at this point that I will use epoxy. I have a digital scale for getting the exact ratios of resin to hardener, and I can buy West Systems at woodcraft down the street.

Perhaps just to be safe, I should pad on a few light washcoats of dewaxed shellac over the epoxy? I don't want any adhesion problems. I plan on using either nitrocellulose lacuqer or a two-part automotive urethane as a clear coat.

The West Systems works well as a filler because it's fairly low viscosity. It sinks way down into the ash, enough that you may need two coats. If you want to, you can also color the epoxy black or brown to make the grain really stand out. I used to use black filled grain under transparent red on my ash bodies.

No need for the shellac. Nitro lacquer or automotive polyurethane will both bond well to sanded West Systems. It's only the polyesters that have some kind of a chemical problem with the amines in the epoxy.

Konquest · #7 03-16-2013, 05:59 PM

Well as it turns out, the only West Systems epoxy was in giant canisters with pump nozzles for boat building, whereas the System 3 stuff was in small bottles. Several reviews said that this particular brand is very particular in mixing ratios, so I used a digital scale to mix by weight. Just got done squeeging on the first coat. It REALLY "ambered" the wood, which isn't too big of a problem for me, but I do plan on sanding it down to wood after how ever many go-rounds I need to fill the pores, instead of leaving a film of epoxy on top of the wood, so we'll see...

miziomix · #8 03-18-2013, 06:44 AM

Quote:

Originally Posted by JLS

Several years ago, Brian Burns gave a presentation on grainfilling, using odorless CA, and a credit card squeegee.

I have done pore filling with CA. It works well. But I don't use it anymore on light colored woods like Ash as it can darken the wood quite a bit. Not all the time though. In fact, rather unpredictably. I have switched to z-poxy finish since. CA is still be a good alternative on darker woods.

gbarcus · #9 03-18-2013, 11:09 AM

I've recently started using system 3 for pore filling after getting frustrated with the other "pore fillers" out there.
I do make sure that all the epoxy is off the surface and just in the pores. The finish can turn out different shades if you don't. It's either that or make sure there is a thin coat of epoxy over the whole thing which is too much work.
CA is too unpredictable time wise for me for pore filling. Having a known set open time is why I like epoxy.

Konquest · #10 03-19-2013, 09:34 AM

Ok, I have smeared the epoxy on the body now twice: squeegied with a credit card on the flats and wiped it onto the curves and corners with a gloved finger. The first coat I sanded down with 240, the second coat with 320. It feels completely smooth. The ash body areas feel smooth and the pores are glossy, if that makes sense. So from what I can tell, that means that the pores are filled with the epoxy and leveled? Is this bass ready for spraying?

Bruce Johnson · #11 03-19-2013, 10:59 AM

Yep, that's the fine art of grain filling. Epoxy and sanding; epoxy and sanding. You should be ready to start your base coats. Spray or brush on a couple of coats of a clear sanding sealer/base coat that's compatible with your main paint. Then level sand that to get the surface completely smooth. That will show up any flaws in the grain filling, shaping, and sanding. Only after the base coats are right do you begin applying any color.