If you sink, you're not a witch, so you're not guilty.
What man are you who is so wise in the ways of Science?
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If you sink, you're not a witch, so you're not guilty.
What man are you who is so wise in the ways of Science?
Well, unfortunately, that's one of the main things we like about epoxy (marine-type epoxies, like West Systems). It sinks deep into the wood and grabs hold really strong. But epoxy has a amber-brown tint that shows up on light colored woods. When you use epoxy to glue lighter colored woods together, the soaked-in glue on either side of the joint will be visible. If I'm gluing a maple fingerboard onto a maple neck, I will usually use LMI's Yellow Instrument Maker's Glue. For that reason.
In this case, you should use the same epoxy as your grain filler. It makes a great grain filler, as you've seen. It sinks into all the pores and dries hard. It's in there forever. Sand back to the surface, and the pores will be filled solid, in that amber-brown color. And they'll never shrink down under the finish. Wipe the whole body with epoxy, sand it back, and it'll all be a uniform smooth base for your finish.
Thanks for your advice. I was planning to use Birchwood-casey grain filler (the one that they sell to go with tru oil), but I suppose epoxy would be better in this case. That way I can be sure that it matches the color of the already filled areas. How thick of a film do I need for filling? Do I rub or scrape it off before it starts curing?
The epoxy should be brushed, dabbed or wiped on. It doesn't really matter. I usually use one of the disposable wool daubers to slop it on, and a scrap of cardboard to push it around and push it down into the pores. But don't scrape all the epoxy off; leave a thin coat on the surface. As the epoxy is curing it will sink down into the pores a little bit. If you scrape all the excess off the surface, trying to save sanding, you may get some little pinhole pockets on the largest grain holes. Then you'd have to do another coat of epoxy.
There's a special technique for sanding epoxy: By hand, coarse paper, very light pressure, in straight lines mostly along the grain, brushing the dust off the paper every couple of strokes. Doing that, sanding the epoxy back to the surface is quick and easy.
Another tip for working with epoxy as your grain filler: Use files on the perimeter of the body, rather than sandpaper. A sharp, fairly coarse file will shave off the epoxy very quickly and leave a smooth surface. Light pressure, and be careful not to dig the file into the wood.
I'm now sanding the whole guitar up to 320 grit and hope to apply the epoxy grain fill tomorrow. One more question about that: How do I keep the epoxy off of my fretboard? I used masking tape around the heel when I glued the neck in, but the epoxy soaked all the way underneath it. Is there a trick?
Really nice thread, thanks for sharing this build!
Can I ask where you get you tatsuta truss rod from in Europe? They sure look interesting!
Thanks, mate! Unfortunately the only way to get them is to order them directly from Japan through their online store. They do not list international shipping rates, but they've been very helpful via email and shipping was very reasonable, especially when ordering several rods at a time.
These rods are my recommendation for any bass or guitar that might suffer from neck dive, they are much lighter than a typical steel truss rod. I also like that the adjustment nut has a 6mm outside diameter, so the whole thing fits into a 6mm channel without widening it at the headstock.
Update #22: Let's try something new twelve days before the deadline
With the guitar sanded to 320 I moved on to pore filling as suggested by @Bruce Johnson. I used the same epoxy (R&G) as I used for the top and neck glue-ups to match the color of previous stains. I wiped it on with a rag, similar to tru oil but a bit more generous. It's a bit streaky, but that's ok for a filler.
This is my first time using epoxy as a filler, we'll see in 24h if this one coat is enough or if I have to do another one. I'm not going for a full gloss finish, so a natural texture (especially on the neck) wouldn't be so bad.
P.S. My tru oil order still hasn't arrived and I'm starting to get a bit nervous.
With the guitar sanded to 320 I moved on to pore filling as suggested by @Bruce Johnson. I used the same epoxy (R&G) as I used for the top and neck glue-ups to match the color of previous stains. I wiped it on with a rag, similar to tru oil but a bit more generous. It's a bit streaky, but that's ok for a filler.
This is my first time using epoxy as a filler, we'll see in 24h if this one coat is enough or if I have to do another one. I'm not going for a full gloss finish, so a natural texture (especially on the neck) wouldn't be so bad.
P.S. My tru oil order still hasn't arrived and I'm starting to get a bit nervous.
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I found a supplier here in the Netherlands who carries them. I don't know about shipping to Sweden.
Dual action truss rod full Titanium 460mm
That's great to know, thanks for posting this. Those look very good, but visually they are not the exact ones that Tatsuta makes.
Looks good so far! You know, if you like the color, you could just finish the bass in epoxy. Marine-type epoxies are intended to be used as the complete finish on wood parts on boats. Epoxy is a tougher, more durable finish than Tru-Oil. Epoxy isn't as hard as polyester, but that's why it's tough. It has excellent resistance to impact, wide temperature changes, chemicals, UV light, salt water, beer, etc.
As you can see, epoxy has a darker amber tint than Tru-Oil or most oil-base finishes. But it's a nice color and looks good over most woods. If you keep adding coats, it will get darker than it is now. The thicker the epoxy is on top of the surface, the darker it will be. Areas that are sanded thinner will get lighter.
So, to complete this finish in epoxy only, you need level sand and wipe on a few more thin coats. Smooth out the lumps and ridges, get the color even all over. When it's all smooth, let it cure for a day or two, then block sand it with fine paper up to maybe 1000 grit. I've found that epoxy sands better dry, just brushing off the paper every couple of strokes. Then buffing it with coarse and fine rubbing compound will take it up to a high gloss. Or, scrub it with #0000 steel wool for a satin sheen. Or anything in between.
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Thanks for the suggestion, Bruce. I'll have to think how I want to proceed. I'm not sure if what I have is marine-grade, it is sold primarily as a laminating resin for composites like fiberglass or CF. I have used it for gluing wood successfully, but I'm not sure if it's suitable for a full finish. When looking at epoxy finish tutorials I see mostly West Systems or Z-Poxy finishing resin.
Here's what I have: Epoxy Resin L + Hardener L (40 min)
Try a sample test. Pick an area on the body that's already pretty flat. Block sand it flat and scrub it with steel wool. Do you like how that looks? All you are doing is finishing up the surface of what you've already put on there.
A laminating epoxy will make a good wood finish. At 90 hardness that particular one should be pretty durable also. Here is an example of a thick coat of a similar epoxy used on a curly maple fretboard:
Oh boy. I sanded the body yesterday. I'll have to do more sanding on the neck today, and I'll have to do a second filler coat in some areas, especially in the end grain areas. Luckily ziricote has small pores and the top and headstock are well filled with a nice smooth surface.
My takeaways are:
1. I'm pretty sure this would make a good finish. It's very hard and probably can be buffed to a nice gloss. The amber color is not too strong in this (fairly thin) coat. That being said...
2. Sanding it is an absolute punishment. I got it sanded to 320 now and I have to wash out the sandpaper every 2 mintes (brushing it out doesn't cut it), and the random orbital sander clogs the sandpaper within seconds, so hand sanding it is. Considering how long it took me to sand this relatively thin coat, it's a major time commitment to do the whole guitar in a thicker epoxy finish, including sanding to a much higher grit.
So, I've made the decision to touch up the filler coat with a second coat in the areas that need it, but then I'll switch to tru oil for the actual finsh coats. With the buildoff deadline closing in I'm sure that an epoxy finish would be rushed and that would be a shame.
I am still intrigued by an epoxy finish and I want to try it for one of my next builds when I have time to do it properly, giving the epoxy enoguh time to cure and to level sand and polish it nicely. Perhaps the twisted sister build could use an epoxy finish. We'll see about that when it's time.
Yes, the trick to sanding epoxy is to treat the sanding block as if it were a hand plane. Long straight strokes, and brush the dust off the paper at the end of every stroke. A stiff bristle brush works better than a shop bench brush. The coolest thing is to mount the brush to your bench, bristles up. Then you just wipe the sanding block across the brush every stroke or two.
If you keep the dust off the sandpaper, epoxy is very easy to sand. Really!
In the contours, it's easier to use smooth files. Same thing, constantly brushing the dust off.
Also consider that most epoxy continues to harden over a period of days to weeks and it seems to clog less when it is harder. I agree, it's not ideal for a buildoff, but if you have more time and can leave it for a week or two after application it might sand better. I find that wet sanding also seems to work better than dry. The water seems to carry away the "dust" so it can't clog the paper so easily.
