Ash body: Tru-Oil, grain filler, sanding sealer, oh my!

[swagbotbilly]

Hello TB,

I am now the ultra-pleased owner of this beautiful (and heavy) ash body that I intend to finish with Tru-Oil. I'm going for a "finished, but not glossy" look. I love the grain which is why I chose this body.

Just arrived today. Per the seller, it has been sanded to 220 grit. However, in reading all over the web, I can't get a good idea for what prep work I need to do.

The only thing I can be sure of is that grain filler is optional -- but I don't have a good feel for what difference it makes, or how I would know if I should or wanted to do it.

So a few questions:

1. If I were going to go straight to the oil, do I need to smooth it any further?
2. What's the "easiest*" way to apply the finish to the rear rout?

Re: grain filler:

1. What exactly does/would applying a grain filler do?
2. Why/why not apply grain filler?
3. Are there any durability gains to be made by applying grain filler?
4. Would grain filler "ease" the transition color between the two body parts? I suspect the TO will do a good enough job of tinting both pieces but...
   
5. Meant to put shellac in the title instead of 'sanding sealer' - jeez, do I need to do that?!
   
6. If you're in the "grain filler - yes" category, what product would you use, and why?

As always, thanks in advance.

 

[swagbotbilly]

To add a bit of context, I am a big fan of the first post in this thread although the commenters are torn on what the actual finishing process looked like for this particular axe.

 

[TFM94]

Long term tru oil user here. It's a great finish for what you are going for.

Ash has fairly large pores, and it will take quite a bit of filling to get everything smooth (as would be necessary for a gloss finish). If I want to have a really smooth surface or a gloss finish, I use epoxy as a grain filler. It's a bit of extra work, but works great.

If you apply tru oil without filler, you will still see and feel the texture of the wood grain, even after several coats. It's not necessarily a bad thing and can have a very nice organic feel.

Sealer of no sealer does not affect the visibility of the center joint. Most sealers are transparent. Tru oil has a slight amber color, but not enough to hide anything.

Another approach I like to use is one or two thin coats of Birchwood casey sanding sealer, then tru oil. The sealer doesn't fill all of the pores completely, but it seals the wood and the tru oil builds up much earlier. While the first coats of tru oil typically soak into the wood and don't build up much of a finish, it starts to build over sealer immediately. Plus, the sealer dries quickly and shows if there are any spots that need further sanding...much easier to fix after sealer than after many coats of try oil...

About surface prep: I typically sand to 320 or 400.

 

[swagbotbilly]

Long term tru oil user here. It's a great finish for what you are going for.

Ash has fairly large pores, and it will take quite a bit of filling to get everything smooth (as would be necessary for a gloss finish). If I want to have a really smooth surface or a gloss finish, I use epoxy as a grain filler. It's a bit of extra work, but works great.

If you apply tru oil without filler, you will still see and feel the texture of the wood grain, even after several coats. It's not necessarily a bad thing and can have a very nice organic feel.

Sealer of no sealer does not affect the visibility of the center joint. Most sealers are transparent. Tru oil has a slight amber color, but not enough to hide anything.

Another approach I like to use is one or two thin coats of Birchwood casey sanding sealer, then tru oil. The sealer doesn't fill all of the pores completely, but it seals the wood and the tru oil builds up much earlier. While the first coats of tru oil typically soak into the wood and don't build up much of a finish, it starts to build over sealer immediately. Plus, the sealer dries quickly and shows if there are any spots that need further sanding...much easier to fix after sealer than after many coats of try oil...

About surface prep: I typically sand to 320 or 400.

This is exactly the advice I was looking for. Re: color, I'm not so worried about the center joint as much as the slight color difference between the two parts--the top piece being a bit darker (gray-er?).

I am hesitant to sand it further just because I'm terrified of becoming impatient and reshaping it too much, it does feel nice and smooth, but I'm under the impression I probably *should* get it to 320 or 400. There is a spot with some, I guess you'd call it tooling? marks along the center joint between the pickup rout and neck pocket. So I guess I ought to maybe sand the whole thing some after all...

When you say the "sealer ... shows if there are spots that need further sanding" what do you mean by that?

 

[Matt Liebenau]

Regarding sanding, for a natural finish I’ll sand up to 320 or 400 grit and wet the surface down before the last sanding to raise the grain. Sometimes I’ll do that twice.

You would grain fill if you want a smooth surface regardless of wether you’re going for gloss, semigloss, satin. If you want to do that there are several options from epoxy on to any of the popular fillers like TimberMate. If I’m applying an oil finish I typically wouldn’t grain fill as I’m generally going for a natural, unfilled wood feel with an oil finish.

Another thing that can be done with a filler is tint it so the grain stands out a bit more on up to something much more obvious like a ceruse or what some of the manufacturers call a dog hair finish. Another thing you can do to partially fill the grain is apply TruOil until it starts to build up, probably 3-4 coats, then use 400 or 600 grit wet dry sand paper to apply the next coat. That makes an oil and sawdust slurry that fills the pores and then hardens as the finish cures. On something like ash that won’t completely fill the grain but it will give a slightly smoother surface.

For an oil type finish it just apply the oil in the control cavity the same way as the rest of the body.

As with a lot of things in instrument building, there’s not real right or wrong. A lot depends on the end result you want and the materials and tools available.

 

[TFM94]

When you say the "sealer ... shows if there are spots that need further sanding" what do you mean by that?

I mean that if there are dings, tool marks or scratches in the wood, for example from sandpaper (220 or lower grit), they will be much more visible after a sealer coat than on raw wood.

I am hesitant to sand it further just because I'm terrified of becoming impatient and reshaping it too much, it does feel nice and smooth, but I'm under the impression I probably *should* get it to 320 or 400.

If it's already at 220 and you only have to sand with finer sandpaper (320, 400), then it is very difficult to reshape it. Those fine sandpapers only take off a small amount. Also, ash is not a soft wood. You can use a random orbital sander on the front and back to speed things up, but hand sanding also works. Great tip by @Matt Liebenau about raising the grain, that definitely helps.

In my experience, preparation is key for a good tru oil finish. Take your time with it, you won't regret it.

 

[Matt Liebenau]

I mean that if there are dings, tool marks or scratches in the wood, for example from sandpaper (220 or lower grit), they will be much more visible after a sealer coat than on raw wood.

If it's already at 220 and you only have to sand with finer sandpaper (320, 400), then it is very difficult to reshape it. Those fine sandpapers only take off a small amount. Also, ash is not a soft wood. You can use a random orbital sander on the front and back to speed things up, but hand sanding also works. Great tip by @Matt Liebenau about raising the grain, that definitely helps.

In my experience, preparation is key for a good tru oil finish. Take your time with it, you won't regret it.

I’ll take the liberty of correcting that last statement to read prep work is the key to any finish. But we are discussing TruOil so there’s that….

 

[Beej]

Every finish I know will accentuate the heck of of that unsanded low part on the top (you called it the tooling marks). I'd be hitting the top with a flat block with 220 to bring it all back to flat, then maybe up to 320 afterwards. Regardless of how well someone else has sanded something, personally I'd make sure and run over the entire thing with the grain at 220 and maybe up to 320.

 

[swagbotbilly]

Thanks everyone. I appreciate all the help.

I am VERY tempted to pick up a random orbital sander, but I may start with a 220 block -> 320 and see how it goes.

 

[mauerkraut_]

I’d recommend checking out Rubio Monocoat Precolor + Oil Plus 2C system. You can go with natural tones or a wilder colors for ceruse look.

 

[swarfrat]

I've had some success shading to lower contrast on glued pieces. I didn't do it on the front because thats nothing but blonde shellac, but on the ash bass i just finished, I did play with toning using a brown/black mix and the airbrush on the back. I was using an Iwata t-shirt/model airplane style airbrush for this not the 4oz "detail" HF spray fun I used for shooting the whole body clear

The Fretless Club (Part IV)

 

[Gilmourisgod]

All good advice above. Ive tried the "sanding slurry as grain filler" technique with Tru-Oil without much sucess. The oil gets gummy pretty quick, and never really filled the grain completely. The epoxy method works well, but its a mess, and if you screw up the mix......i used Zpoxy last time, its pretty clear, without the pinkish cast of West System, and simple 50/50 mix. I just painted it on with a chipping brush and then scraped it off with an old credit card. Even so, it took two coats of epoxy. Definitely something to be said for the more "natural" look with a little grain showing, and that's a nice looking body. Tru Oil isnt a super hard, durable finish, but has the advantage of being easily repaired later by just adding more oil. Really stupid easy if you just let the grain show through!

 

[rojo412]

I frequently build and ONLY use TruOil. It's fantastic for sealing in wood, yet keeping it very natural feeling and it's easy to repair in the future.

On ash, it does a nice job coloring it, and if the "open pore" look is something you're good with, it's the easiest thing ever. This is what it looks like when completed, no grain fill, no accent, just TruOil:

In the sun:

When it comes to the cavity, I personally don't add finish to the inside of it, I use nickel shielding paint and like for that to soak into the wood as much as possible, so as to create a (hopefully) more effective shielding.
But if you need to do it, then just rubbing it in there will be fine.

 

[Chop11777]

Here is my experience with ash try oil finishing .
I have attached a photo
I sand and polish the body up to 2000 grit ... I then sand in the tru oil with 2000 grit paper
Rub in oil maybe 2 or more coats to desired finish
The body just rings out acoustically with sustain for days
Take your time and hope it turns out to your liking
Chop!!!

 

[swagbotbilly]

I frequently build and ONLY use TruOil. It's fantastic for sealing in wood, yet keeping it very natural feeling and it's easy to repair in the future.

On ash, it does a nice job coloring it, and if the "open pore" look is something you're good with, it's the easiest thing ever. This is what it looks like when completed, no grain fill, no accent, just TruOil:

View attachment 4973586

In the sun:

View attachment 4973587

When it comes to the cavity, I personally don't add finish to the inside of it, I use nickel shielding paint and like for that to soak into the wood as much as possible, so as to create a (hopefully) more effective shielding.
But if you need to do it, then just rubbing it in there will be fine.

Here is my experience with ash try oil finishing .
I have attached a photo
I sand and polish the body up to 2000 grit ... I then sand in the tru oil with 2000 grit paper
Rub in oil maybe 2 or more coats to desired finish
The body just rings out acoustically with sustain for days
Take your time and hope it turns out to your liking
Chop!!!
View attachment 4973609 View attachment 4973610

Yeah - y'all have convinced me. I'm gonna just do the TO. Beautiful guitars!

 

[Ric5]

This is my Fenderbird with an ash body. It has several coats of hand rubbed tru oil. lightly sanded between coats. No grain filler.